Table of Content

12 January 2008, Volume 34 Issue 01

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Cloning and Expression Analysis of the Dihydroflavonol 4-reductase Gene in Brassica juncea

YAN Ming-Li;LIU Xian-Jun;LIU Zhong-Song;GUAN Chun-Yun;YUAN Mou-Zhi;XIONG Xing-Hua

Acta Agron Sin. 2008, 34(01):  1-7.  doi:10.3724/SP.J.1006.2008.00001

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The yellow-seeded cultivars of rapeseed have higher oil content than those of the black-seeded varieties. Yellow seeds of rapeseed have lower fibre content compared with those of black-seeded varieties. They may also have higher protein content than black seeds. Higher protein content and lower crude fibre content are desirable traits in rapeseed meal, which is the most important fodder product of rape. However, there is little knowledge on the biosynthesis of seed coat color in rapeseed. Therefore, it is necessary to elucidate the mechanism of seed coat color in rapeseed. Dihydroflavonol 4-reductase (DFR) gene is a key gene in the way of proanthocyanidins biosynthesis of seed coat in Arabidopsis thaliana, its mutation caused transparent testa. In order to study molecular mechanism of seed coat color in rapeseed, dihydroflavonol 4-reductase (DFR) gene was cloned from Brassica juncea using homology-based cloning strategy. The cloned gene of 1 612 bp contains 5 introns. The complementary DNA (cDNA) consists of 1 214 bp and has an open reading frame of 1 158 bp encoding a deduced polypeptide of 385 amino acids with a predicted molecular weight of 42 886.0 Da and an estimated isoelectric point of 5.54. RT-PCR analysis showed that DFR expressed in leaves, embryos and seed coats of Purple-leaf Mustard (PLM) and two black-seeded near-isogenic lines (NILs) developed from backcross breeding using Sichuan Yellow (SY) as a current parent, whereas the gene expressed only in the leaves and embryos of SY, not in the seed coats. No expression of DFR blocked the biosynthesis of anthocyanidins and proanthocyanidins in yellow seed coats, and seeds displayed yellow appearance because of transparent testa. So DFR is a key gene for the formation of seed coat color in B. juncea. This work provided a foundation for understanding molecular mechanism of seed coat color and developing novel yellow-seeded rapeseed germplasm through antisense expression or RNAi-suppression of DFR gene in black-seeded cultivars using a seed- or seed-coat-specific promoter.

Inheritance of Resistance to Lamprosema indicata (Fabricius) in Soybean

XING Guang-Nan;ZHAO Tuan-Jie;GAI Jun-Yi

Acta Agron Sin. 2008, 34(01):  8-16.  doi:10.3724/SP.J.1006.2008.00008

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Bean pyralid (Lamprosema indicata Fabricius) is one of the major leaf-feeding insects for soybeans and causes serious damage in soybean production in central and southern China. The objective of the present study was mainly to reveal the inheritance of resistance to L. indicate in soybeans using three recombinant inbred line (RIL) populations derived from susceptible by resistant crosses, i.e. NJRIKY, NJRIWT and NJRISX (derived from Kefeng 1 × Nannong 1138-2, Wan 82-178 × Tongshanbopi-huangdoujia and Su 88-M21 × Xinyixiaoheidou, respectively) in the field under natural infestation. Based on the observation of symptoms damaged by the insect on soybeans, rolled leaf percentage, rolled leaf number, and seed yield were examined as resis-tance (damage) indices. Among them, the rolled leaf percentage tested in early September was the best index of resistance to L. indicata due to its higher genetic variation, heritability value and environment-stability, as well as higher negative correlation with seed yield in the three populations. Segregation analyses showed that resistance to L. indicata was dominated by two major genes plus polygenes in the three populations, with their major gene heritability of 51.0%, 80.5%, and 56.3%, and polygene heritability of 39.1%, 11.4%, and 29.1%, respectively. The major gene genotypes of the RILs of the three populations were determined and grouped according to their posterior probability, which could be utilized as reference in selection for resistance lines.

Evaluation and Validation of Four Molecular Markers Associated with Pre-Harvest Sprouting Tolerance in Chinese Wheats

YANG Yan;ZHAO Xian-Lin; ZHANG Yong;CHEN Xin-Min;HE Zhong-Hu;YU Zhuo;XIA Lan-Qin


Acta Agron Sin. 2008, 34(01):  17-24.  doi:10.3724/SP.J.1006.2008.00017

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Pre-harvest sprouting (PHS) of wheat (Triticum aestivum L.) reduces the quality and economic value of the grain. Increasing PHS tolerance is one of the most important objectives in wheat breeding. In this study, three PHS tolerance- associated markers MST101, wmc104, and Xgwm155, as well as Vp1B3, which was developed in our previous study, were employed to evaluate 95 Chinese landraces and historical varieties, aimed at assessing the efficiency of these markers in selecting genotypes with higher PHS tolerance. Among the 95 genotypes tested, 57, 19, and 19 accessions had germination indexes (GI) less than 30%, 30%–60%, and over 60%, respectively. The relationships between the variation of the PCR products of the four markers and the germination indexes of the tested accessions were analyzed. Variations at Vp1B3 and Xgwm155 were associated with PHS resistance, but not the STS marker MST101 and STMS marker wmc104. Whereas Vp1B3 was more effective than Xgwm155 for selecting PHS resistant varieties, the selection efficiency would be greatly improved by use of both markers.

Peanut Core Collection Established in China and Compared with ICRISAT Mini Core Collection

JIANG Hui-Fang;REN Xiao-Ping;LIAO Bo-Shou;HUANG Jia-Quan;LEI Yong;CHEN Ben-Yin;GUO B Z;HOLBROOK C C;UPADHYAYA H D

Acta Agron Sin. 2008, 34(01):  25-30.  doi:10.3724/SP.J.1006.2008.00025

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The core collection has been well accepted as a useful way to improve the efficiency of crop germplasm evaluation, conservation and utilization. Around 6 390 accessions of cultivated peanut (Arachis hypogaea L.) have been collected in China. In order to characterize and utilize the germplasm more efficiently for further crop improvement, the available morphological and biochemical data were analyzed to develop a core collection. The entire collection was first stratified by botanical types and then grouped by origin locations. Based on the data of 15 morphological and biochemical characters, the accessions in each botanical type were clustered by SAS method. From each cluster, five to ten percent of the accessions were randomly selected to form a core collection consisting of 576 accessions, which was 9.01% of the entire collection. The genetic variation in the entire collection was well presented in the core collection based on comparison of diversity index of the involved traits in both entire and core collections. Comparison between the newly selected Chinese peanut core collection and the introduced mini core collection consisting of 184 lines established at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) indicated that there were wider diversities in the var. hirsuta and vulgaris as well as in leaf length, leaf width, seed length, seed width in the Chinese core collection. The ICRISAT peanut collection had wider diversities in var. hypogaea and fastigiata as well as in plant height and number of total branches than Chinese peanut resource.

Cloning and Expression Analysis of a Vacuolar ATPase Subunit A Gene in Maize

MAO Yi-Hui;LI Hui-Yong;WANG Tian-Yu;RONG Ting-Zhao;SHI Yun-Su;SONG Yan-Chun;LIU Ying-Hui;LI Yu

Acta Agron Sin. 2008, 34(01):  31-36.  doi:10.3724/SP.J.1006.2008.00031

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V-ATPase is commonly found in plants and plays a vital role in abiotic stress tolerance. Cloning and expression analysis of the gene(s) encoding key V-ATPase subunit(s) are helpful to elucidate its regulation and response under diverse stresses. The aim of this study was to investigate expression and characterization of a V-ATPase subunit gene from Zea mays. On the basis of a SSH library constructed from maize inbred line “CN165” under drought stress, we got a uni-EST which has high similarity with other plant vacuolar H-+ATPase subunit A (VHA-A) through BLAST(NCBI) similarity analysis, thereafter the RACE technique was used to amplify the 5′ and 3′ends of H-+ATPase gene, respectively. Finally, a full-length cDNA (2 414 bp) was obtained, which contained an open reading frame (ORF) of 1 863 bp encoding a 620 aa protein, a 5′-untranslated region of 293 bp and 3′-untranslated region of 257 bp, then named ZmVHA-A. Bioinformatics methods were performed for the gene structure and mo-lecular similarity analysis. Two conserved domains, GAFGCGKT and PSVNWLISYS, interacted with the phosphate groups of the coding region, indicating the highly conserved vacuolar H-+ATPase subunit A. Homologous analysis showed that the amino acids sequence had the identity of 92.7%, 89.8%, and 89.8% with the rice, wheat, and barley H-+ATPase subunit A, respectively. To evaluate the response of ZmVHA-A gene to different abiotic stresses, transcript levels of ZmVHA-A was examined in maize. Northern blotting analysis revealed that ZmVHA-A gene was induced by water stress and showed different responses to salt, cold, and ABA treatment in maize seedling stage. The results showed that a full length H-+ATPase subunit A gene (ZmVHA-A) was gained in maize by RACE, which was a highly conservative functional subunit and participated in adaptation of V-ATPase to stress by transcriptional regulation. The ZmVHA-A gene was up-regulated under diverse abiotic conditions.

Analysis of the Genetic Diversity in Different Types of Sugar Beets by SRAP and SSR Markers

WANG Hua-Zhong;WU Ze-Dong;WANG Xiao-Wu;FANG Zhi-Yuan

Acta Agron Sin. 2008, 34(01):  37-46. 

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Sugar beet (Beta vulgaris L.) is one of the most important sugar crops in the world. However, the application of molecular markers in sugar beet greatly lags behind that in other field crops. In the present study SRAP and SSR markers were employed to investigate the genetic diversity and relationships of sugar beet in order to make full use of germplasm reasonably, to select parents for breeding programs accurately, to improve breeding efficiency and to identify target cultivars quickly. We analyzed 49 sugar beet accessions, including monogerm lines (including male sterilities and maintainors), polygerm tetraploids, polygerm diploids, F₁ of monogerm cross combinations, and foreign varieties introduced. All these materials are conserved at Sugar Beet Research Institute, CAAS. In a preliminary experiment, four accessions markedly distinct in phenotype were used to screen 64 pairs of SRAP primers and 11 pairs of SSR primers. Finally, 11 pairs of SRAP primers and nine pairs of SSR primers were selected and used for the present study. A total of 199 SRAP bands (including 86 polymorphic bands) were detected and one primer pair produced 18.0 bands on average (including 7.8 polymorphic bands). The ratio of polymorphic SRAP bands was from 33.3% to 62.5%, with an average of 43.7%. The selected SSR primers yielded 35 bands, with an average of 3.9 per primer pair, and the ratio of polymorphism was as high as 100%. The average genetic distance in the 49 accessions was 0.3860 and the average genetic similarity was 0.6795. About 30% of accessions were significantly different in average genetic distance or genetic similarity. The highest genetic similarity occurred between polygerm tetraploid lines (0.7264), followed by that between F₁ of monogerm cross combinations (0.7243) and that between foreign varieties introduced (0.7060), while the lowest one was found between monogerm lines (0.6837). The 49 accessions were divided into A, B, C and D groups based on cluster analysis. About 40% of accessions belonged to the D group which was divided into 4 subgroups, including diploids, tetraploids, F₁ of monogerm cross combinations and foreign varieties introduced, which also showed high genetic diversity. Thus, the combination method with SRAP and SSR markers is economic, effective and reliable to assess genetic diversity and relationships of sugar beet. The results indicate that sugar beet has a high level of heterogeneity. There are a definite difference between foreign genetic background and native genetic background, and the closer relationships and narrower genetic basis. Introducing foreign germplasm in breeding has shorted the gap between China and other countries in sugar beet genetic basis among cultivars in production. The classification based on the identification of biological and economical properties in field experiments was generally in accord with that based on SRAP and SSR molecular markers. Therefore, the application of the technology of molecular markers in sugar beet will accelerate breeding process and improve the quality, the yield and the content of sugar.

Effects of Genotype, Location, and Genotype by Location Interaction on Main Wheat Quality Traits in Inner Mongolia

LI Yuan-Qing;WU Xiao-Hua;CUI Guo-Hui;ZHANG Yong;ZHANG Yan;YU Mei-Ling;WANG Xiao-Bin;HE Zhong-Hu;MA Wen-Xing

Acta Agron Sin. 2008, 34(01):  47-53.  doi:10.3724/SP.J.1006.2008.00047

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In our previous investigation on grain quality of Chinese spring sown wheat (Triticum aestivum L.), we sampled two sites from Inner Mongolia and got primary result of location effect on grain quality. To map out the regional planning of quality of spring wheat grown in Inner Mongolia, we need to study the effects of genotype, location, and their interaction on wheat quality systematically under different eco-regions. In the present experiment, we used 9 cultivars including strong (4), medium (3), and weak (2) gluten types, to evaluate main wheat quality traits including grain hardness, protein content, mixograph properties and starch pasting parameters. All cultivars were sown at 6 representative locations in Inner Mongolia with completely randomized block design in 2003 and 2004. The results indicated that all of the wheat quality traits tested were significantly influenced by genotype and location effects, and were also significantly affected by genotype by location interaction effect except for grain protein content. The group of cultivars with strong gluten strength was characterized by high protein and ash content, high Zeleny sedimentation value, strong mixograph performance, medium flour yield, and good starch pasting parameters; the group of cultivars with moderate gluten strength was characterized by high flour yield and strong mixograph properties, but low ash content and poor starch pasting quality; while the group of cultivars with weak gluten strength was characterized by high ash content, good starch pasting parameters, but low grain hardness, protein content, flour yield, and sedimentation value, as well as weak mixograph properties. Significant differences for all quality parameters across locations were observed. Samples collected from Wuhai generally showed high ash content, strong mixograph performance, but low grain hardness and sedimentation value, and poor starch pasting parameters. Samples from Hangjinhouqi had high flour yield, medium starch pasting parameters and mixograph properties, but low protein content and sedimentation value. Samples from Hohhot expressed high grain hardness, protein and ash content, sedimentation value, and strong mixograph properties, but poor milling quality and starch pasting parameters; samples from Chifeng had medium values for all the traits; samples from Tongliao had high grain hardness and protein content, good starch pasting parameters, medium to strong mixograph properties, and medium for the other traits. Samples from Eerguna showed high protein content and sedimentation value, but weak mixograph properties. Based on the above information, Hohhot and Wuhai were the most suitable regions while Eerguna was not the suitable region for the production of cultivars with strong or medium strong gluten strength. It also showed that all the 6 locations were not suitable for the production of cultivars with weak gluten strength. The results provided some basic information for wheat breeding as well as quality wheat production zoning in Inner Mongolia.

QTL Identification for Fatty Acid Content in Rapeseed (Brassica napus L.)

ZHANG Jie-Fu;QI Cun-Kou;PU Hui-Ming;CHEN Song;CHEN Feng;GAO Jian-Qin;CHEN Xin-Jun;GU Hui;FU Shou-Zhong


Acta Agron Sin. 2008, 34(01):  54-60.  doi:10.3724/SP.J.1006.2008.00054

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Rapeseed is one of the important oil crops in China, and the change of the composition in fatty acid content can affect the value of oil for edible and industrial use. QTLs linked to main fatty acid composition can be used for marker-assisted selection in fatty acid composition improvement in rapeseed. A segregation population BC₁F₁, derivered from a cross between a low erucic acid content line APL01 and a high erucic acid content variety M083 in Brassica napus L., was used to construct a genetic map and identify QTLs linked to main fatty acid composition in rapeseed. The genetic map containing 19 linkage groups was constructed with 251 markers of RAPD, SSR, and SRAP in rapeseed. Via WinQTLCart scanning, five QTLs linked to palmitic acid (C16:0) content were identified, which were located on linkage groups N3, N8, N10, and N13.The main-effect QTLs qPA8-1 and qPA13 linked to palmatic acid content in rapeseed explained 11.31% and 14.47% of the palmitic acid content variation in segregation population BC₁F₁, respectively. Three QTLs linked to stearic acid (C18:0) content were identified, which were located on the linkage groups N1, N8, and N16. The main-effect QTL qST16 accounted for 12.22% of phenotypic variation. Two QTLs, qOL8 and qOL13, both the main-effect QTLs linked to oleic acid (C18:1) content, were located in the region of m11e37b–A0226Ba267 on linkage group N8 and m18e46–m20e25a on N13, and accounted for 11.73% and 27.14% of phenotypic variation, respectively. Three QTLs linked to linoleic acid (C18:2) content were identified, and the main-effect QTL qLI8-1 accounted for 13.25% of phenotypic variation. Three QTLs, qLN1, qLN8, and qLN11, linked to linolenic acid (C18:3) content were identified, but they had a rather small effects on C18:3, and could be regarded as minor-QTLs. Four QTLs linked to eicosenoic acid (C20:1) content, and three of them, qEI8-1, qEI8-2, and qEI13, were main-effect QTLs, accounting for 12.20%, 10.22%, and 11.14% of phenotypic variation, respectively. Two QTLs qER8 and qER13, both the main-effect QTLs linked to erucic acid (C22:1) content, were located in the region of m11e37b–A0226Ba267 on linkage group N8 and A0301Bb398–m18e46 on N13, accounting for 16.74% and 31.32% of phenotypic variation, respectively. The main-effect QTLs linked to fatty acid content, which were located in the region near marker m11e27b on linkage group N8 and m18e46 on linkage group N13, could be used in marker-assisted selection in fatty acid improvement in rapeseed.

QTL Analysis for Chlorophyll Content in Four Grain-Filling Stage in Rice

A JIA La-Tie;ZENG Long-Jun;XUE Da-Wei;HU Jiang;ZENG Da-Li;GAO Zhen-Yu;GUO Long-Biao;LI Shi-Gui;QIAN Qian


Acta Agron Sin. 2008, 34(01):  61-66.  doi:10.3724/SP.J.1006.2008.00061

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A double haploid (DH) population consisting of 120 lines derived from the cross between a japonica parent Chunjiang 06 and an indica parent TN1 was used to detect QTLs for controlling chlorophyll content in four times of grain-filling stage in rice. Seven chlorophyll-content QTLs were detected and distributed on chromosomes 4, 6, and 8. Expression of QTLs for chlorophyll contents in different times varied. The QTLs detected in the third leaf from top mainly expressed in the early times of grain-filling, and the QTLs detected in the Penultimate and flag leaves expressed in the later times. Four chlorophyll-content QTLs were detected in the first and second times, only three and two QTLs detected in the third and fourth times, respectively. Total contribution rates of the QTLs in the four grain-filling times reduced gradually, indicating chlorophyll content was higher in early times of grain-filling, which is just close relative to leave aging. qCHL2, qCHL4-1, qCHL4-2, qCHL8-1, and qCHL8-2 made effects on chlorophyll contents in early and middle stages of grain-filling, qCHL6-1 and qCHL6-2 were detected from flag leaf in third and fourth stages, respectively, indicating the two QTL were just closely relative to the “keeping green” on aging for flag leaves.

QTL Mapping of Tofu and Soymilk Output in RIL Population NJRISX of Soybean

ZHANG Hong-Mei;ZHOU Bin;ZHAO Tuan-Jie;XING Han;CHEN Shou-Yi;GAI Jun-Yi

Acta Agron Sin. 2008, 34(01):  67-75.  doi:10.3724/SP.J.1006.2008.00067

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Genetic improvement of tofu and soymilk output is interested by both farmers and processors. The objective of the present study was to reveal the genetic system and map QTLs of tofu and soymilk output for improvement of the traits. The RIL population NJRISX consisting of 176 families was derived from a cross Su88-M21×Xinyixiaoheidou and was tested in two cropping years (2005 and 2006). A genetic linkage map, containing 131 SSR markers, spanning 24 linkage groups (LG) at a total length of 2 044.6 cM, with an average distance of 15.6 cM between the flanking markers was constructed by using MAPMAKER 3.0. Genetic analysis was performed under main gene plus polygene mixed inheritance model for the P1, P2, and RIL population and QTLs were mapped with both composite interval mapping (CIM) and multiple interval mapping (MIM) of the software Win QTL Cartographer Version 2.5 on output of dried tofu, wet tofu and dried soymilk. The main QTL qODT-A2-1 associated with dried tofu output, explaining 15.7%-28.2% of the total phenotypic variation was identified between Satt424 and Sat_162 on LG A2; the main QTL qODS-A2-1 related to dried soymilk output, explaining 30.0%-34.8% of the phenotypic variation was also between Satt424 and Sat_162 on LG A2; and two main QTLs qOWT-A2-1 and qOWT-L associated with wet tofu output, explaining 20.7%-30.7% and 19.0%-27.4% of the total phenotypic variation were identified between Satt424 and Sat_162 on LG A2 and between Satt481 and Sat_397 on LG L, respectively. The results from segregation analysis showed that dried tofu and soymilk output were dominated by one main gene plus polygenes and wet tofu output was by two unlinked main genes plus polygenes. In comparison, the number of main genes, the phenotypic variation proportion explained by the main genes, and the relative contribution of main gene vs. ploygene from both segregation analysis and QTL mapping were similar, and two genetic analyses could be used for verification each other. From described above, it was inferred that breeders for tofu and soymilk output should pay attention to both main genes and polygenes.

Cloning and Expression of Cellulose Synthase Gene in Ramie [Boehme- ria nivea (Linn.) Gaud.]

TIAN Zhi-Jian;Yi Rong;CHEN Jian-Rong;GUO Qing-Quan;ZHANG Xue-Wen;

Acta Agron Sin. 2008, 34(01):  76-83.  doi:10.3724/SP.J.1006.2008.00076

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In this study, total RNA was extracted from ramie, and then cDNA was obtained through reverse transcription. Degenerate primer was designed to amplify a fragment of cellulose synthase gene so as to obtain the gene using RACE. The fragment contained the whole 3′-end with ploy(A) and most 5′-end excluding 450 bp of the 5′-end of the expected cDNA. There sequences were sequenced respectively and spliced into a cDNA sequence which was 3 276 bp in length, and could be translated into protein with 938 amino acids in the reading frame. BLAST and protein structure analysis confirmed that this cDNA sequence was the Ramie cellulose synthase gene. According to the cellulose synthase gene denomination regulation, it was designated as BnCesA1 and submitted to GenBank l. Its accession number is DQ077190. In order to investigate the expression and regulation mechanism of BnCesA1 in different tissues of Ramie, the nonconservative sequence at 3′-end of BnCesA1 was amplified by semi-quantitative RT-PCR respectively at the same time. Taking 18S rRNA gene as an inner control, the integrate optic density (IOD) of BnCesA1 and 18S rRNA gene bands were detected with gel analysis software and defined the ratio of IOD as relative expressive quantity. The results indicated the expression of BnCesA1 could be found in leaf, stem, root and bud in Ramie. The expression level in tissues from high to low is stem, leaf, bud and root, with the relative content of 0.791, 0.381, 0.319, and 0.183 respectively. The deduced BnCesA1 protein shows a high concordance and homology to Arabidopsis thaliana AtCesA1 (87/93%). Thus BnCesA1 maybe serve a dual role as a CesA involved in both primary and secondary cell wall biosynthesis. Further studies are currently in progress to substantiate this hypothesis.

SSR Analysis of Powdery Mildew Resistance Gene in a New Germplasm N9628-2 of Triticum aestivum L.

LIU Su-Lan;WANG Chang-You;WANG Qiu-Ying;JI Wan-Quan

Acta Agron Sin. 2008, 34(01):  84-88.  doi:10.3724/SP.J.1006.2008.00084

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Powdery mildew, caused by Blumeria graminis D C f. sp. tritici (former Erysiphe graminis f. sp. tritici), is one of the devastating diseases of wheat (Triticum aestivum L.). So far, a total of 34 resistance genes have been formally named. However, very few of them are used in wheat production due to resistance lose and close linkage to ill agronomic traits. The new resistant germplasm N9628-2, which was derived from the backcross of Am9 (F₁ progeny of the cross between tetraploid wheat-Aegilops amphidiploid and a sensitive wheat cultivar “Shaan 160”) and Shaan 160, showed highly resistant to Guanzhong 4, the prevailing Blumeria graminis f. sp. tritici race in Shaanxi province. In the present study, we aimed to identify the resistance gene in N9628-2, and locate it on wheat chromosome. The F₁ (308 plants) and F₂ (275 plants) populations derived from crosses of N9628-2 and highly susceptible cultivars Shaan 160 and Shaanyou 225 were inoculated with powdery mildew race Guanzhong 4 at the seedling stage for resistance identification. The parents and F₂ individuals were used for gene location with 208 pairs of SSR markers including 38 pairs polymorphic marker between two parents, and the result was verified by analyzing Chinese Spring nullisomic-tetrasomic and ditelosomic lines. According to inoculation test, the resistance to powdery mildew in N9628-2 was controlled by a single dominant gene (χ² = 0.038 and 0.068 in Shaan 160 ´ N9628-2 and Shaanyou 225 ´ N9628-2, respectively; χ20.05 = 3.84). Two markers Xwmc553 and Xwmc684 on chromosome 6A generated polymorphic DNA fragments between the resistant and susceptible pools, indicating the resistance gene might be located on chromosome 6A and linked to the two markers. The resistance gene was further located on chromosome 6AS by the absence of the above polymorphic DNA fragments only in Chinese Spring 6A nullisomic-tetrasomic and 6AL ditelosomic lines. The genetic distances between the resistance gene and the two markers, calculated by Kosambi’s formula, were 10.99 (Xwmc553) and 7.43 cM (Xwmc684) respectively. Our research found that the resistance gene in N9628-2 was probably a new gene differing from the reported resistance genes PmY39, PmPS5B (Pm33), and PmPS5A.

Identification of Wheat Chromosomes Sorted by Flow Cytometry

GUO Dong-Wei;HU Gan;SHE Mao-Yun;LI Lian-Cheng;CHEN Ming;XU Zhao-Shi;MA You-Zhi


Acta Agron Sin. 2008, 34(01):  89-94.  doi:10.3724/SP.J.1006.2008.00089

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Construction of chromosome specific BAC library plays an important role for simplifying sequencing, physical mapping and gene cloning of plant with complexity genome such as common wheat, identification of sorted chromosome is a vital step of library construction. Although there were some reports about identification of sorted chromosomes using different methods, the sorted chromosomes were different normal chromosomes and the applicability and feature of various identification methods had also not been commented by the numbers yet. Based on previous research, the identifications of 6VS, 3B and 7BL chromosomes (arms) sorted from ditelosomic and common wheat were performed through fluorescence in situ hybridization (FISH), primed in situ DNA labeling (C-PRINS) and PCR amplification methods respectively. The results showed that all of these three methods could efficiently identify the flow sorted chromosomes. The chromosome staining before flow sorting and chromosome damage from physical shear force during chromosome suspension preparation and flow sorting did not impact obviously the results of identification. After comparing to these three protocols, the PCR approach was the fastest with better repetition which adapted to determine rapidly constitute of chromosomal peaks on the univariate flow karyotype histogram, but there were no visible signals and the purity of sorted chromosomes could not be determined were the disadvantages of this approach. The FISH approach could provide a visible and repetitive result and was suit for identifying purity of the sorted chromosomes, but it was time-consuming, complex and necessary for special probes. C-PRINS combined the advantages of FISH and PCR, had potential for chromosomes identification, although the hybridization signals was instable and repetition was not so good at present, if combined this method with in situ hybridization in suspension, a new way for chromosome flow sorting might be set up. The features of these three methods, some key points during the identification process and their applicability also were discussed.

Identification of Maize Low Phytic Acid Inbred Lines and Primary Study of Its Genetic Mechanism

WANG Hui;CHEN Jing-Tang;LIU Li-Juan;CHEN Hao;LIU Guo-Zhen

Acta Agron Sin. 2008, 34(01):  95-99.  doi:10.3724/SP.J.1006.2008.00095

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It is well known that the phytic acid (myo-inositol-1, 2, 3, 4, 5, 6-hexakisphosphate or Ins P6) in maize (Zea mays), wheat (Triticum compactum), rice (Oryza sativa), and soybean (Glycine max) is an anti-nutritional factor in grains, phytic acid typically
represents approximately 80% of maize seed total phosphorus. The identification of mutants with low phytic acid (lpa) is a possible solution to solve the problem. In this study, the content of inorganic phosphorus of twenty maize inbred lines were analyzed by colorimetric reagent, the inorganic phosphorus content of Qi 319 was about 0.93 mg mg^-1, which was higher than that of control material
(0.15 mg mg^-1), further investigation of phytic acid based on standard curve indicated that the content of phytic acid in Qi 319 grains was 1.31 mg mg^-1, close to the maize lpa241/lpa241 mutant (1.20 mg mg^-1) identified by Nielsen’s laboratory in 2003, which was
significantly lower than that of Lpa241/Lpa241 wild type and control maize inbred lines (>2.8 mg mg^-1). F₁ seeds derived from Qi
319 and wild type Lpa241/Lpa241 crossing showed low inorganic phosphorus, indicated that the gene controlling low phytic acid of
Qi 319 was recessive, homozygous low phytic acid seed was identified from Qi 319 ×/Lpa241/lpa241 F₁ seeds suggested that lpa loci of Qi 319 may allelic to lpa241/lpa241. To investigate the mechanism of lpa in Qi 319, the content of myo-inositol-3-phophate
synthase (MIPS) was assayed Western blot by using anti-MIPS antibody derived from Arabidopsis MIPS protein, according to se
quence analysis, the similarity of amino acid between maize and Arabidopsis MIPS protein is 88%. In contrast with the low content of
MIPS in lpa241/lpa241, the expression of MIPS in Qi 319 increased significantly, suggesting that both mutants are related to MIPS,
but their mechanism is different from each other. It is worthwhile to point out that the agronomic behavior of reported lpa mutant is not satisfying for breeding applications, while Qi 319 is a wildly used inbred line with several combinations in production. This discovery will broaden its application and provide a novel resource for lpa breeding program.

Developing Rice Lines Resistant to Bacterial Blight and Blast with Molecular Marker-Assisted Selection

NI Da-Hu;YI Cheng-Xin;LI Li;WANG Xiu-Feng;ZHANG Yi;ZHAO Kai-Jun;WANG Chun-Lian;ZHANG Qi;WANG Wen-Xiang;YANG Jian-Bo

Acta Agron Sin. 2008, 34(01):  100-105.  doi:10.3724/SP.J.1006.2008.00100

Abstract ( 2264 )   PDF (605KB) ( 1300 )   Save

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The bacterial blight (BB) and blast are two major diseases of rice. Through Molecular Marker-assisted Selection (MAS) and traditional breeding methods, hybridization and selfcross, blast resistance gene Pi9(t), BB resistant genes Xa21 and Xa23 were put together. Four stable lines L17–L20 which conferred 3 homozygous resistance genes and good agronomic characteristics were obtained through consecutive inoculation in the field or/and greenhouse, MAS and selection from agricultural aspects. By artificial inoculation of 20 blast isolates which came from different countries and areas, 7 Chinese epidemic bacterial blight races and an Anhui epidemic BB race in the field or/and greenhouse, 4 lines expressed resistance to blast and BB. L17–L20 had high resistance to all 20 blast isolates and showed similar resistant level to and same resistant spectrum as donor variety 75-1-127. At the same time, lines L17–L20 had similar resistance and spectrum to Xa23 gene both in seedling and heading stages. In the adult stage, the lines had better BB resistance than donor parents M12 with Xa21 gene and CBB23 with Xa23 gene. Using multi-PCR, gene Pi9(t) and Xa21 can be selected at the same time so that improves the selection efficiency.

Male Sterility Induced by Chemical Hybridizing Agent SQ-1 in Common Millet

CUI Xiu-Hui

Acta Agron Sin. 2008, 34(01):  106-110.  doi:10.3724/SP.J.1006.2008.00106

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Effect of chemical hybridizing agent SQ-1 on common millet was studied with the split plot design. The different treatment stages and dosages of SQ-1 were designed as main plot and sub-plot respectively. Male sterility induced by SQ-1 was evaluated according to the three indexes: male sterile rate, crossing rate, and seed-setting rate of natural pollination. The results showed that treatment stages, dosages of SQ-1 and the interaction between them affected male sterile rate and crossing rate significantly or highly significantly. The induced male sterile rate and crossing rate were both over 95% with treatments of different dosages (4.0 and 5.0 kg ha^-1) in the differentiation stage of the anlage of gynoecium and stamen, and also under the dosage of 5.0 kg ha^-1 at the primary stage of forming pollen. The seed-setting rate of natural pollination was not affected significantly by the treatment stages, but affected significantly by the dosages and interaction between the treatment stages and dosages, and decreased with the dosage. Considering all the three indexes and the cost of production of hybrid seed, the optimum treatment stage is the differentiation stage of the anlage of gynoecium and stamen and the optimal dosage is 4.0 kg ha^-1.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Hormones in Rice Spikelets in Responses to Water Stress during Meiosis

YANG Jian-Chang;LIU Kai;ZHANG Shen-Feng;WANG Xue-Ming;WANG Zhi-Qin;LIU Li-Jun

Acta Agron Sin. 2008, 34(01):  111-118.  doi:10.3724/SP.J.1006.2008.00111

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The stage of meiosis is the most stress-sensitive period of reproduction in rice (Oryza sativa L.). However, the underlying biochemical mechanism is poorly understood. This study was to investigate whether and how plant hormones are involved in the regulation of spikelet sterility when subjected to water stress during meiosis. Two rice cultivars, Han A-3 (HA-3, drought-resistant) and Wuyujing 7 (WY-7, drought-susceptible), were used and subjected to well-watered (WW) and water-stressed (WS) treatments during meiosis (15-2 d before heading). Leaf water potentials of both cultivars markedly decreased during the period as a result of WS treatment, but panicle water potentials remained constant. The percentage of sterile spikelets in WS plants was increased by 48.5 to 50.9% for WY-7, whereas only by 12.6 to 12.8% for HA-3. Concentrations of zeatin + zeatin riboside, indole-3-acetic acid and gibberellins (GA₁ + GA₄) in spikelets showed no significant differences either between the WW and WS treatments or between the two cultivars. Abscisic acid (ABA), ethylene, and 1-aminocylopropane-1-carboxylic acid were all enhanced in spikelets by the water stress, with more enhanced for ethylene than for ABA in WY-7, whereas elevated ABA balanced ethylene production in HA-3. The spikelet sterility was significantly reduced when amino-ethoxyvinylglycine (an inhibitor of ethylene synthesis) or ABA was applied to the panicles of WS plants at the early meiosis stage. Application of ethephon (an ethylene-releasing agent) or fluridone (an inhibitor of ABA synthesis) had the opposite effect. The results suggest that antagonistic interactions between ABA and ethylene may be involved in mediating the effect of water stress that affects spikelet fertility. A higher ratio of ABA to ethylene would be a physiological trait of rice adaptation to water stress.

Characteristics of N Accumulation and Translocation in Rice Genotypes with Different N Use Efficiencies

WEI Hai-Yan;ZHANG Hong-Cheng;HANG Jie;DAI Qi-Gen;HUO Zhong-Yang;XU Ke;ZHANG Sheng-Fei;MA Qun;ZHANG Qing;ZHANG Jun

Acta Agron Sin. 2008, 34(01):  119-125.  doi:10.3724/SP.J.1006.2008.00119

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N is yet the most important and largest input required in rice production although over use of N causes so many environment problems. N use efficiency is varied in different rice genotypes. Therefore it is necessary to identify the physiological mechanism of N absorption and utilization in different rice genotypes in order to increase N use efficiency through rice cultivar improvement. In this research, field experiment with 225 kg ha^-1 N fertilizer application and twelve rice genotypes (6 N-efficient and 6 N-low-efficient ) selected from 120 rice cultivars grown in Yangzhou during 2004 and 2005 were carried out in 2006 on the farm of Yangzhou University, Jiangsu province, China. Relationship between N use efficiency and indexes of rice N accumulation and translocation was analyzed. At the three growth stages including critical stage of productive tillering, heading, and maturing, the amount of N accumulation of N-efficient rice was obviously higher than that of N-low-efficient genotypes while at the stage of elongating, there was no significant difference in N accumulation between the two rice genotypes. In order to analyze the N accumulation progress of rice genotypes with different N use efficiency, the growth was also divided into four phases including from transplanting to critical stage of productive tillering, from critical stage of productive tillering to elongating, from elongating to heading and from heading to maturing. Results revealed that the amount of N accumulation of N-efficient genotypes was significantly higher than that of N-low-efficient genotypes during all growth phases except the phase from critical stage of productive tillering to elongating, at which the amount of N accumulation of N-efficient genotypes was significantly lower than that of N-low-efficient genotypes. The percentage in N accumulation of N-efficient genotypes was higher than that of N-low-efficient genotypes during the growth phases from elongating to heading and from heading to maturing while it showed the reversed trend during the phases from transplanting to critical stage of productive tillering and from the critical stage of productive tillering to elongating. The amount and the efficiency of N translocation before heading were obviously higher in N-efficient genotypes than those in N-low-efficient genotypes. On the contrary, the contribution rate of transferred N to the total N of rice grain at maturity was significantly lower in N-efficient genotypes than that in N-low-efficient genotypes. For N efficient genotypes, the amount of N accumulation before the critical stage of productive tillering was modest. And during the phase from the critical stage of productive tillering to heading, its N accumulation of usefulness was large while the N accumulation of uselessness was few. Therefore, till the stage of rice heading, the amount of N accumulation of N-efficient genotypes was obviously higher than that of N-low-efficient genotypes. And the amount and the efficiency of N translocation before heading of N-efficient genotypes were also higher than that of N-low-efficient genotypes. Because of the strong ability of N accumulation of N-efficient genotypes after heading, its contribution rate of transferred N to the total N of rice grain at maturity was relatively lower than that of N-low-efficient genotypes before heading.

Effects of Cultivation Methods on the Absorption and Use Efficiency of Phosphorus in Upland Rice and Paddy Rice

ZHANG Ya-Jie;YANG Jian-Chang;DU Bin

Acta Agron Sin. 2008, 34(01):  126-132.  doi:10.3724/SP.J.1006.2008.00126

Abstract ( 1969 )   PDF (337KB) ( 1444 )   Save

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Upland rice and dry-cultivated paddy rice have been attracted more and more attention because of limited water resources in China, however, there is little information available on effect of cultivation methods on P absorption and use efficiency of upland rice and paddy rice. The objective of this study was to evaluate the difference between upland rice cultivar Zhonghan 3 (japonica) and paddy rice cultivar Wuxiangjing 99-8 (japonica) under three cultivation methods of moist cultivation (MC, control), plastic film mulching cultivation (PFMC), and bare cultivation (BC). Compared with the MC, the grain yield was significantly lower under PFMC for upland rice, but no significant difference between PFMC and MC for paddy rice, and significantly reduced under BC for both upland rice and paddy rice. P concentration and the amount of P absorption in plants under PFMC and MC were lower, whereas P concentration decreased more slowly from heading to maturity stage under PFMC and BC. The proportion of P in leaves was lower, whereas significantly higher in culms and sheaths for upland rice, and was significantly higher under PFMC and significantly lower under BC for paddy rice under dry cultivation than under MC. P use efficiency of matter production (PUEp) was significantly greater under dry cultivation than under MC after heading stage and P use efficiency of grain yield production (PUEg) was lower under PFMC and higher under BC than under MC. Compared with Wuxiangjing 99-8, Zhonghan 3 exhibited lower P concentration and slower decrease in P concentration, smaller P accumulation in plants at later growth stage, higher proportion of P in leaves and grains, greater PUEp, higher PUEg and P harvest index (PHI), no difference at maturity and lower change range of the proportion of P in plants and PUEg production under three cultivations. The amount of P absorption was very significantly positively correlated with adventitious root numbers, root weight, and grain yield (r1 = 0.8227**, r2 = 0.7928**, r3 = 0.7344**). The results suggest that the effect of dry cultivation on the absorption and use efficiency of P varies largely with the cultivation methods and variety types, and dry cultivation could increase PUEp.

Production Performance in Alfalfa with Different Classes of Fall Dormancy

WANG Cheng-Zhang;HAN Jin-Feng;SHI Ying-Hua;LI Zhen-Tian;LI De-Feng

Acta Agron Sin. 2008, 34(01):  133-141.  doi:10.3724/SP.J.1006.2008.00133

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Fall dormancy (FD) in alfalfa is related to regrowth, yield and plant height in autumn. The objectives of this research were to evaluate variability for agronomical traits among 42 alfalfa varieties with fall dormancy classes ranging from 2 to 9 in Zhengzhou, China. The results were as follows: (1) The dry matter yields (DM) of 42 varieties in 2004 and 2005 were higher than those in 2002, and the yield in 2002 was higher than that in 2003, due to the low temperature and high rainfall in 2003; (2) DM yields of fall dormant and semi-fall dormant alfalfa were higher than those of non-fall dormant alfalfa; (3) Cutting times had a significant effect on DM herbage yield, with the highest yield in the first cutting and the lowest in the fifth. The first 3 cuttings in the spring and early summer should be paid attention for the alfalfa yield; (4) The non-fall dormant alfalfa should not be selected in the production of Zhengzhou, because FD classes had extremely significant negative correlation with CP content and DM yield (P＜0.01), and positive correlation with CF.

Simulation on Oil Accumulation Characteristics in Different High-Oil Peanut Varieties

CHEN Si-Long;LI Yu-Rong;XU Gui-Zhen;CHENG Zeng-Shu

Acta Agron Sin. 2008, 34(01):  142-149.  doi:10.3724/SP.J.1006.2008.00142

Abstract ( 2063 )   PDF (351KB) ( 1332 )   Save

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To investigate accumulation characteristics of seed oil in different oil-used peanut varieties and screen a suitable growth equation to describe the seed oil accumulation, six high oil varieties were used and tested by the Richards, Logistic and Gompertz equations. The results showed that the Richards equation was more suitable for simulating oil accumulation process than the other growth equations in peanut. The Richards could improve fitting effect among the three models. Via comparing the accumulation characteristics of seed oil content in different oil-used peanut cultivars, the accumulation of seed oil in peanut could be divided into three stages, which were initial accumulation stage, fast accumulation stage and steady accumulation stage. There were two ways for oil-used peanut cultivars to increase oil content: increasing the rate of seed oil accumulation and extending the time of seed oil accumulation process. From the results of parameters of growth equation, the important strategies in increasing the seed oil content are as follows: (1) Enhancing the maximum rate of oil accumulation; (2) Increasing the oil accumulation at the initial accumulation stage; (3) Increasing the proportion of oil accumulation at fast accumulation stage.

Starch Accumulation and Related Enzyme Activities in Superior and Inferior Grains of Large Spike Wheat

LIANG Tai-Bo;YIN Yan-Ping;CAI Rui-Guo;YAN Su-Hui;LI Wen-Yang;GENG Qing-Hui;WANG Ping;WANG Zhen-Lin

Acta Agron Sin. 2008, 34(01):  150-156.  doi:10.3724/SP.J.1006.2008.00150

Abstract ( 2250 )   PDF (373KB) ( 1208 )   Save

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Starch, the major component of grain, consists of amylose and amylopectin. It is synthesized and accumulated during grain filling in wheat (Triticum aestivum L.), and regulated by many enzymes including sucrose synthase (SS), adenosine diphosphorate glucose pyrophosphorylase (AGPase), uridine diphosphorate glucose pyrophosphorylase (UGPase), soluble starch synthase (SSS), granule-bound starch synthase (GBSS), starch branching enzyme (SBE) and so on. According to recent studies, AGPase, starch synthase, and SBE are the key enzymes controlling starch synthesis. Previous researches have revealed that the allocation of carbohydrate, grain weight, and the transformation of sucrose to starch were significantly different between superior and inferior grains of wheat. But to date, there are few reports about the differences of starch accumulation and the relationship between starch accumulation and related enzyme activities in superior and inferior grains. Therefore, a field experiment was carried out, and two large-spike type cultivars, SN 12 and PH01-35 were used to investigate the mechanism of starch accumulation and the relationship with related enzyme activities in superior and inferior grains. Forty spikes was sampled at 7, 14, 21, 28, and 35 d after anthesis, and partitioned into two groups, superior grain (the 1st and 2nd grains from the basal part of a spikelet) and inferior grain (the 3rd and 4th grains from the basal part of a spikelet). Half grains of each group were used to determine the enzyme activities, and the other half for starch content measurement. The result showed that the accumulation of amylose and amylopectin in superior grain were significantly higher than those in inferior grain. The simulation with Logistic equation showed that the accumulation rate and initial potential were higher, the accumulation duration was longer, so the starch final amount was higher in superior grain. The activities of SS, AGPase, UGPase, SSS, and GBSS changed in the pattern of a single-peak curve during grain filling. The related enzyme activities in superior grain, which had higher starch accumulation, were higher than those in inferior grain. The sucrose content in inferior grain was much higher than that in superior grain at 7–14 d after anthesis, indicating that the substrate of starch synthesis should not be the limiting factor for starch accumulation in inferior grain, which related to starch synthesis efficiency, also the number of endosperm cells at early grain filling stage.

Effect of HgCl₂ Short Time Treatment on Photosynthesis in Broad Bean Leaves

WANG Hong-Wei;SHI Ya-Qi;HUANG Feng;YUAN Lin

Acta Agron Sin. 2008, 34(01):  157-162.  doi:10.3724/SP.J.1006.2008.00157

Abstract ( 2120 )   PDF (425KB) ( 1300 )   Save

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Mercury pollution is a major environmental problem. Unlike most heavy metals, plants uptake mercury primarily through leaves rather than the root system. Most of the mercury existed as complexes of Hg2+, which could cause the inhibition of photosynthesis as well as plant growth in higher plants. Since photosynthesis is very sensitive to heavy metals in higher plants, green algae and cyanobacteria, the inhibition of photosynthesis by Hg²⁺ had been examined in CO₂ fixation and photosystems activities. However, in most of the researches, Hg²⁺ solutions were applied in vitro or not directly on plant leaves, the mechanism of inhibition on photosynthesis by Hg²⁺ is still in controversy. In order to discover its effect on leaf photosynthesis, HgCl₂ solutions were applied to intact broad bean (Vicia faba L.) leaves. In the experiment, Hg²⁺ contents in intact broad bean leaves were determined after 30 min treatment with different concentrations of HgCl₂ solution. And leaf gas exchange and chlorophyll fluorescence were measured under a definite light intensity and CO₂ concentration. The results showed that the Hg content in leaves increased with the increase of treated Hg concentrations at the range from 0.5 mg L^-1 to 2 000 mg L^-1. When the applied HgCl2 concentration was 0.5 mg L^-1, the increase of leaf mercury content compared with that of control was less than 20%. If the applied HgCl₂ increased to 500 mg L^-1, Hg content in leaves was about 800% of control. Meanwhile, leaf net photosynthetic rate (P_n) was unaffected at the treated HgCl₂ concentrations from 0.5 mg L^-1 to 5.0 mg L^-1, and gradually decreased with the increase of treated Hg concentrations from 10 mg L^-1 to 2 000 mg L^-1. The inhibition of leaf’s P_n was about 36% after 2000 mg L^-1 HgCl₂ treatment. The results suggested that broad bean could absorb mercury solution through the leaves and thus lead to the inhibition of leaf photosynthetic activities.
Further studies showed that both leaf’s apparent quantum yield (AQY) and electron transport rate (ETR) were decreased significantly, with the increase of HgCl2 concentrations. Moreover, the quantum yield of PSⅡ(DF/F_m′) were inhibited whereas the non-photochemical quenching (NPQ) was increased by HgCl₂ concentrations from 20 mg L^-1 to 2 000 mg L^-1, indicating that the decrease of Pn in broad bean leaves by low concentrations of HgCl₂ solutions short time treatment might be mainly due to the inhibition of photosynthetic electron transport caused by the decrease of light energy transferring to active center and the increase of the light energy dissipation in PSⅡ.


RESEARCH NOTES

Screening and Analysis of Resistance to Silique Shattering in Rape (Brassica napus L.)

WEN Yan-Cheng;FU Ting-Dong;TU Jin-Xing;MA Chao-Zhi;SHEN Jin-Xiong;ZHANG Shu-Fen


Acta Agron Sin. 2008, 34(01):  163-166.  doi:10.3724/SP.J.1006.2008.00163

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The silique shattering resistance index (SSRI) of 229 accessions (Brassica napus L.) was investigated through random impact test (RIT) for screening silique shattering (SS) resistance. The accessions displayed wide variation in SSRI, which ranged from 0.000 to 0.7675 with the variance coefficient (CV) of 114.4%. Only two varieties (accounting for 0.9%) showed SS resistance; about 3.93% of the varieties (lines) showed relative resistance to SS; and about 8.73% were identified as the medium. Most (59.38%) of the varieties (lines) were identified as very susceptible germplasm to SS, and 27.07% as the susceptible germplasm. According to independent experiments in three years with 6 representative varieties (lines), the SSRI was dominated by genetic factor with obvious interactions with environment, and the RIT showed stable results within years. The simple correlation analysis showed that the SSRI had significant (P<0.01) negative correlation with silique number per centimeter, and significant (P<0.01) positive correlations with silique wall thickness, silique length, silique width, beak length, and seed number per silique. However, the correlation coefficients (CV) were rather small indicating the selection potential of varieties with high SSRI and fine silique traits via recombination in B. napus breeding programs.

Primary Study on HMW-GS Inheritance Affected by 1BL/1RS Translocation

GENG Hui-Min;ZHAN Huai-Qiong;REN Zheng-Long;

Acta Agron Sin. 2008, 34(01):  167-170.  doi:10.3724/SP.J.1006.2008.00167

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The common wheat (Triticum aestivum L.) Chuannong 18 with 1BL/1RS translocation chromosome, whose HMW-GS components is (1, 7+9, 2+12) as male and female parent respectively was crossed with Chuannong 19 (N, 7+8, 2+12). Both the female and male gametes of their F₂ progenies showed significantly (P<0.01) lower rate of 1BL/1RS translocation compared with the theoretical value (75%), in which female gamete (65.1%) had higher rate than male gamete (52.4%). In both crosses, HMW-GS subunits (encoded by Glu-A1 and Glu-B1) of parents were all transmitted to F₁ progenies as dominant trait, but deviated the Mendel’s segregation ratios at Glu-B1 and the combination of Glu-A1 & Glu-B1 loci in F₂ progenies. We also found and confirmed a variant seed in F₁ of Chuannong 19 × Chuannong 18 by detecting its genome DNA with 33 pairs of specific SSR markers and the components of HMW-GS and gliadin of its F₂ progeny. The HMW-GS patterns of the variant seed were (1, 7+8, x+9, 2+12). The band of variant subunit was similar to 1Bx6 by SDS-PAGE analysis, which was between 1Dx5 and 1Bx7.

Effects of Rewatering after Drought Stress on Photosynthesis and Yield during Flowering and Boll-Setting Stage of Cotton Under- Mulch-Drip Irrigation in Xinjiang

LUO Hong-Hai;ZHANG Ya-Li;ZHANG Wang-Feng;BAI Hui-Dong;HE Zai-Ju;DU Ming-Wei;ZHANG Hong-Zhi

Acta Agron Sin. 2008, 34(01):  171-174.  doi:10.3724/SP.J.1006.2008.00171

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In order to develop water saving irrigation stratagem and increase cotton yield in Xinjiang, we did the irrigation experiment in the field, controlled the lower limit of soil relative moisture content in layer of 0–60 cm at 45%, 60%, and 75% (the control) respectively of field water-holding capacity, which was the upper irrigation limit, and studied the effects of rewatering after drought on photosynthesis and yield during flowering-boll stage of cotton under-mulch-drip irrigation. The result showed that drought reduced the parameters of gas exchange. Photochemical quenching coefficient (qP) and P_SⅡ photochemical quantum yield (Ф_PSⅡ) were reduced but non-photochemical quenching coefficient (NPQ) was increased significantly under moderate drought. Net photosynthetic rate (P_n) and stomatal conductance (G_s) of three water treatments could be rapidly recovered within three days after rewatering, and the recovery of mild drought treatment was the most rapid. The recovery of Ф_PSⅡ and qP in three water treatments was similar to that of P_n which achieved the maximum in 2–3 days after rewatering. The NPQ of three water treatments decreased significantly in 1–2 days after rewatering. From early flowering stage to early full boll stage, accumulation of single plant photosynthate was not much different from that of mild drought treatment after rewatering and the control, but the accumulation of single plant photosynthate was decreased significantly from later full boll stage to boll opening stage that let the seed cotton yield in mild drought treatment after rewatering be lower than that in control. Accumulation of single plant photosyn-thate and seed cotton yield in moderate drought treatment after rewatering was always lower than that in mild drought treatment and control.