Table of Content

12 July 2013, Volume 39 Issue 07

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Event-Specific PCR Detection Method of Genetically Modified Maize MIR162 and Its Standardization

ZHANG Guang-Yuan,SUN Hong-Wei,LI Fan,YANG Shu-Ke,LU Xing-Bo,ZHAO Lei

Acta Agron Sin. 2013, 39(07):  1141-1147.  doi:10.3724/SP.J.1006.2013.01141

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Genetically modified maize MIR162 with resistances to Lepidoptera insects is developed by U.S. Syngenta Company through recombinant DNA technology. The purpose of this study was to establish and standardize the event-specific detection method of this line in China. The primers and Taqman probe were designed based upon the revealed 3' and 5' flanking sequences of MIR162. After validated by six external laboratories, results showed that the qualitative PCR detection method could specifically detect the samples of MIR162 with the detection sensitivity about 0.1%, a good repeatability and reproducibility. The quantitative PCR system was based on TaqMan. Two standard curves and corresponding linear regression equations of Quantitation-Ct between endogenous zSSIIb gene and transgenic target gene of MIR162 maize in standard material were generated. Results showed that the standard curves had good linear relationships. Their R² values both were 0.999 and the recovery rates were 98.622% and 99.602%. Moreover, the standard deviations (SD) and relative standard deviations (RSD) of repeatability ranged from 0.014 to 0.209 and 0.049% to 0.879%. The limit of detection (LOD) was 0.01%. Thereafter, three mixed corn samples containing 1.0%, 0.5%, and 0.1% MIR162 were quantified employing the developed quantitative PCR method, and the quantified bias between the true value and tested value was below 8%. All these results suggested that the developed qualitative and quantitative PCR methods can be used for the identification and quantification of GM maize MIR162.

Genetic Analysis and Gene Fine Mapping of Rice Lesion Mimic Mutant c5

CHEN Hong-Lin,XIANG Yang-Hai,ZHAO Ji-Ying,YIN De-Dong,LIANG Guo-Hua,ZHAI Wen-Xue,JIANG Guang-Huai

Acta Agron Sin. 2013, 39(07):  1148-1154.  doi:10.3724/SP.J.1006.2013.01148

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The lesion mimic mutant c5 was obtained bytreating the seeds of japonica variety Zhonghua 11 with chemical mutagen EMS (ethyl methane sulfonate). The phenotypes and main agronomic traits of the c5 mutant were investigated. There were many nearly circularbrown spots began to appear on c5 leaves at 3-leaf stage. These leaves were stained further with DAB and trypan blue respectively and indicated that there were excessive H₂O₂ production and clusters of dead cells in the lesion tissues. Compared with the wild-type, the height of c5 plant decreased from 110.4 cm to 74.6 cm, the number of effective tiller per plant and spikelet per panicle were reduced by 23.7% and 28.5% respectively, thousand-grain-weight and seed setting rate were significantly dropped.In addition, c5 is endowed a broad-spectrum resistance to bacterial blight resistance to ten Philippine races of X. oryzae pv. Oryzae (Xoo). Genetic analysis showed that the lesion mimic mutant c5 was controlled by a single recessive nuclear gene. Minghui86 was crossed with c5 and 6269 individuals of F₂ population and 18 pairs of molecular markers were used for gene mapping. And thegene was further mapping to rice chromosome 5 in a 102 kb region between STS markers S41 and S47. Sequence analysis of the 102 kb region revealed that there were 11 candidates for c5 gene. All the 11 candidate genes were different from those lesion mimic genes reported previously, which suggested that the phenotype of c5 may be controlled by a novel gene.

Identification of Wild Segments Associated with Stem Termination, Pod Color and Seed Coat Color in Soybean

WANG Wu-Bin,HE Qing-Yuan,YANG Hong-Yan,XIANG Shi-Hua,XING Guang-Nan,ZHAO Tuan-Jie,GAI Jun-Yi

Acta Agron Sin. 2013, 39(07):  1155-1163.  doi:10.3724/SP.J.1006.2013.01155

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Stem termination (ST), pod color (PC) and seed coat color (SCC) are important morphological traits, which are related to evolution in soybean. By using a wild soybean (Glycinne soja Sieb et Zucc.) chromosome segment substitution line (CSSL) population, designated as SojaCSSLP1 composed of 151 lines, one ST, three PC and two SCC wild segments/alleles were detected based on the comparison of different CSSL groups with a same phenotype on the respective trait. Among them, five wild alleles/segments identified in this study were corresponding to Dt₁, L₂, L₁, G and em, respectively, which indicated that there existed allele differentiation happened between wild and cultivated soybean as well as between cultivated soybeans on these loci/segments and that the genes/segments involved with domestication and evolution. The wild segment of Satt273 for PC might be a novel gene/segment, which needed further verification. The identification of the genes/segments provide basic materials for cloning the wild alleles, studying the wild allele function and recombination of the wild alleles/segments.

Molecular Cloning and Functional Analysis of a GDSL Lipase Gene from Gossypium hirsutum L.

TONG Xiang-Chao,WANG Li-Man,HU Wen-Jing,ZHANG Xue-Ying,ZHANG Tian-Zhen,GUO Wang-Zhen

Acta Agron Sin. 2013, 39(07):  1164-1171.  doi:10.3724/SP.J.1006.2013.01164

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GDSL and GXSXG lipases are two important sub-families of lipases. Unlike the GXSXG motif-containing lipases, GDSL lipases have a GDSL motif and are active in hydrolysis and synthesis of abundant ester compounds. In this experiment, a EST sequence (GenBank accession No: DR458916) was screened based on extremely significant expression differences at fiber initiation stages between lintless-fuzzless XinWX and linted-fuzzless XinFLM isogenic lines by 29K cotton genome array hybridization. Using the EST sequence as queries, the Gossypium EST database (http://www.ncbi.nlm.nih.gov/) was screened and the corresponding cDNA sequences containing a complete ORF were assembled. Further, the ORF information was reconfirmed in transcriptional and genomic level. As a result, a novel gene encoding GDSL lipase was cloned, and the gene was designated as GhGDSL (Gossypium hirsutum GDSL; GenBank accession number: KC186125). GhGDSL included an open reading frame of 1 065 bp that encoded a polypeptide of 354 amino acids. The genome sequence indicated that GhGDSL had four introns and five exons. The homolog of GhGDSL had one copy in diploid cotton species G. herbaceum and G. raimondii and two copies in tetraploid cotton species G. hirsutum acc. TM-1 and G. barbadense cv. Hai 7124, respectively. Sequence alignment from different cotton species showed GhGDSL homoelogs in tetraploid were evolved independently, with more variations in D-subgenome than in A-subgenome. GhGDSL homoelogs in tetraploid were located on chromosome 4 (Chr. A4) and chromosome 22 (Chr. D4) by developing subgenome-specific SNP marker, respectively. Q-PCR analysis showed that GhGDSL was accumulated highly in ovule and fiber tissue at 3–10 days post anthesis (DPA), with expression peak at 8DPA in Hai7124 and high expression from 5DPA to 10 DPA in TM-1. The association analysis between GhGDSL and the traits related to fiber and seed qualities in corresponding [(TM-1×Hai7124)×TM-1] BC1S1 individuals showed that GhGDSL homolog in A-subgenome was significantly correlated with the seeds’ fat content (P=0.048), and GhGDSL homolog in D-subgenome was very significantly correlated with the seeds’ protein content (P=0.008). These results suggested that GhGDSL might be functionally important in the metabolic process of lipid and protein in seeds and in the process of fiber development.

Inheritance of Several Traits in Mungbean (Vigna radiata)

WANG Li-Xia,CHENG Xu-Zhen,WANG Su-Hua,LIU Yan

Acta Agron Sin. 2013, 39(07):  1172-1178.  doi:10.3724/SP.J.1006.2013.01172

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Seed coat color and anthocyanidin coloration are important traits for variety identification and marker assisted selection in mungbean. Based on the phenotypes of progenies from different combinations, we analyzed the inheritance of the traits above. The results showed that seed coat color was controlled by mono-gene, and green was dominant to yellow, while black was dominant to green. The seed luster had a complicated genetic model, and there was no relationship between seed coat color and luster. The inheritance of anthocyanidin coloration on different parts of plant was also agreeable to mono-gene. However, the relationships among of anthocyanidin coloration among different parts of plant were not similar. The genes controlling anthocyanidin coloration in seedlings and in leaf base might be tightly linked together or be the same, while the gene controlling anthocyanidin coloration in keel was not linked with other genes.

Analysis of Resistance to Verticillium Wilt in Cotton by Reciprocal Grafting and Real-time Quantitative PCR

HAO Jun-Jie,HU Yu-Wei,GUO Xiao-Qin,ZhAO Fu-An,JIA Xin-He,GUO Li-Juan,ZHANG Zhi-Xing,WANG Qing-Dong

Acta Agron Sin. 2013, 39(07):  1179-1186.  doi:10.3724/SP.J.1006.2013.01179

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In an attempt to better understand the resistance mechanism of controlling cotton Verticillium wilt by locating responsible for resistance in the plant, reciprocal grafts were made between resistant (Gossypium barbadense, Hai 7124 and Pima 90) and susceptible (G. hirsutum, Jimian 11) genotypes. The grafting combinations were inoculated with Verticillium dahliae. Quantitative monitoring of colonization of V. dahliae in different parts of the plant was analyzed using Real-time quantitative PCR (qPCR). When comparing resistant/susceptible or susceptible/resistant grafted combinations with their resistant and susceptible self-graft checks, respectively, disease index of reciprocal grafts and IC (infection coefficient) values of different parts of the plant were nearly within a range between their corresponding checks, respectively, indicating the pathogens could be transferred through the graft union in reciprocal grafts. The disease index was significantly related with average IC values in different parts of plant in different cotton types. Susceptible/resistant grafted combinations showed basal stem of resistant genotypes had an important role on inhibiting translocation of the pathogens, and resistant/susceptible grafted combinations also showed upper stem above graft union with the resistant ability to V. dahliae in resistant genotypes, which indicated that the resistant genotype G. barbadense has the whole-plant of resistance to V. dahliae. In addition, it seems that all parts of the plant in susceptible genotypes (G. hirsutum) were susceptible to V. dahliae.

Association Analysis of Yield Traits with Molecular Markers in Huang-Huai River Valley Winter Wheat Region, China

ZHANG Guo-Hua1,GAO Ming-Gang,ZHANG Gui-Zhi,SUN Jin-Jie,JIN Xue-Mei,WANG Chun-Yang,ZHAO Yan,LI Si-Shen

Acta Agron Sin. 2013, 39(07):  1187-1199.  doi:10.3724/SP.J.1006.2013.01187

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Grain yield is an important breeding target in wheat, which is controlled by complex genetic factors and strongly influenced by environments. In this study, the yield and yield-related traits of 128 wheat varieties/lines from the Huang-Huai River Valley Winter Wheat Region were evaluated in four growing environments. A total of 64 SSR, 27 EST-SSR and 47 functional markers were used to genotype these varieties/lines. Ninety-one SSR and EST-SSR markers produced 315 alleles, with 2–7 alleles on each locus and an average of 3.5. Forty-seven functional markers produced 107 alleles, with 2–5 alleles per locus and an average of 2.3. A total of 49 markers were significantly associated (P ≤ 0.005) with yield traits. Of which, 38 loci were associated with the same trait when analyzed by using the phenotypic values in multiple environments or using the average values, and 16 loci were associated with at least two traits simultaneously. Some favorable alleles associated with yield traits in multiple environments were discovered, such as Ax2*-null and UMN19*-A362 for reducing plant height, barc21-A220 for increasing spikelet length, gpw2111-A156 for increasing fertile spikelet number per spike, swes65-A120 for increasing spikelet number per spike, VRN-A1*-A1068 for increasing spike number, cfd5-A215 for increasing kernel number per spike, and wmc626-A170 for increasing thousand-kernel weight. These results may provide useful information for marker-assisted selection in wheat breeding programs for yield traits.

A High Through-Put Protocol of Plant Genomic DNA Preparation for PCR

WANG Hui-Na,CHU Zhi-Zhan,MA Xing-Liang,LI Ri-Qing,LIU Yao-Guang*

Acta Agron Sin. 2013, 39(07):  1200-1205.  doi:10.3724/SP.J.1006.2013.01200

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Preparation of large numbers of plant genomic DNA (gDNA) samples for PCR in basic researches and molecular breeding in crops is a time-consuming and laborious work. In this study we developed a protocol for rapid and high through-put preparation of plant gDNA for PCR. A piece (about 30 or 40 mm in length, the same as the depth of the used 96-deep well plates) of rice (or other monocot plants) seedling leaf, or about 2–4 mg of dicot plant leaf tissue, was put into each well of 96-deep well plates. After adding a tungsten bead and 150 μL buffer [10 mmol L^-1 Tris (pH 9.5), 0.5 mmol L^-1 EDTA, 100 mmol L^-1 KCl] in each well, the plates were sealed with silicon rubber caps, and vigorously shaken with a vortex shaker for 3–5 min, followed by a brief centrifugation for a few seconds. For the pieces of monocot seedling leaves (30 or 40 mm in length), only the bottom parts (about 8 mm, ca. 2–4 mg) could be broken by the tungsten beads. Small amounts (ca. 0.5–1.0 μL each) of the crude gDNA solutions containing about 2–3 ng gDNA μL^-1 were directly transferred with a 96-pin replicator (or a multiple-channel pipetter) to 96-well PCR plates containing PCR solution (15–20 μL each well) for various types of PCR markers, such as Simple Sequence Repeat (SSR) and Insertion Deletion (InDel). Our tests showed that too large amounts (2 μL or more) or too high concentration (>10 mg broken tissue in 150 μL solution) of the gDNA in PCR could suppress the amplification reaction, due to the carrying-in of higher levels of inhibitory materials from the crude gDNA solution. Therefore, it is important to control a suitable ratio of the amount of broken plant to the volume of tissue/preparation solution (ca. 2–5 mg, but no more than 10 mg in 150 μL solution). The PCR amplifications with the template gDNAs prepared by this protocol are reliable for amplification of PCR markers and relatively large (>1 kb) DNA. This 96-formated high through-put/low-cost method is especially suitable for genotyping large numbers of plant samples.

Temporal Changes in Resistance Gene Analog Polymorphism of Major Rice Varieties in Guangdong Province

TANG Zhi-Ming,CHEN Jian-You,LU Yong-Fa,ZHOU Hua-Cheng,MO Xue-Jiao,MAO Xing-Xue,LI Xiao-Fang

Acta Agron Sin. 2013, 39(07):  1206-1213.  doi:10.3724/SP.J.1006.2013.01206

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In order to investigate the temporal diversity of resistance gene analogs (RGA) from major rice varieties in Guangdong, landraces from early 1950s and major varieties from 1972, 1980, 1994, and 2008 in Guangdong Province were selected and analyzed using three RGA primers. One hundred and seventy-one varieties were divided into twenty groups according to the DNA band data at the similarity index of 0.81. Landraces from early 1950s and varieties form 1972, 1980, 1994, and 2008 were distributed into eleven, seven, four, eight and eleven groups, with their Nei polymorphism index of 0.801, 0.682, 0.493, 0.603, and 0.527, respectively. The RGA polymorphism of landraces was the highest. Having a few group types and unevenly distributing in different groups were the reasons of low diversity for the varieties of 1972, 1980, and 1994, while the low diversity for varieties of 2008 resulted from that major varieties distributed in one group and unevenly distributed among different groups. Thus, having various groups and evenly distribution is necessary for maintaining the resistance diversity of varieties. In recent years, the resistance diversity of rice varieties in Guangdong decreased as major varieties had similar genetic background in resistance. Thus, different resistant resources should be utilized equally in future rice breeding.

Analysis of QTLs for Oil, Protein, Cellulose and Hemicellulose Contents of Seeds in Brassica napus L.

MA Zhen-Zhen,LI Jia-Na,Benjiamin WITTKOP,Martin FRAUEN,YAN Xing-Ying,LIU Lie-Zhao,XIAO Yang

Acta Agron Sin. 2013, 39(07):  1214-1222.  doi:10.3724/SP.J.1006.2013.01214

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In order to study oil, protein, cellulose and hemicellulose contents of rapeseed, recombinant inbred lines (RILs) were developed through successive selfing up to eight generations from the F₂ of a cross between yellow seeded female parent GH06 and black seeded male parent P174. The SSR markers were used to construct the linkage map, containing 31 linkage groups with the total map length of 1437.1 cM and an average distance of 3.89 cM. We measured the RIL population seeds quality in four different environments, the result showed that the oil content was negatively correlated with other three traits, and there were a negative correlation between protein content and cellulose content and a positive correlation between protein content and hemicellulose content. Using the method of composite interval mapping (CIM) to analysis oil, protein, cellulose and hemicellulose contents, a total of 26 QTLs for affecting the four traits were detected in linkage groups of N2, N3, N8, N9, N11, N13, N16, and N17. Eight QTLs were detected for oil content and the contribution for phenotypic variation ranged from 4.96% to 21.83%, six QTLs were detected for protein content and the contribution for phenotypic variation ranged from 3.12% to 14.28%, four QTLs were detected for cellulose content and the contribution for the phenotypic variation ranged from 4.60% to 17.29%, eight QTLs were detected for hemicellulose content and the contribution for phenotypic variation ranged from 6.66% to 16.68%. Furthermore, overlapping regions were observed in linkage group N8 between QTLs of oil content and QTLs for hemicellulose content, andin linkage group N9 between QTLs of cellulose content and QTLs for hemicellulose content. These results suggested that oil, protein, cellulose and hemicellulose contents are typical quantitative traits. They are controlled by many minor effect genes and influenced by environment. Molecular markers linked with these QTLs will be useful for facilitating molecular marker-assisted breeding.

Genetic Analysis and Fine Mapping of a Lesion Mimic Mutant spl31 in Rice

DAI Gao-Meng,ZHU Xiao-Yan,LI Yun-Feng,LING Ying-Hua,ZHAO Fang-Ming,YANG Zheng-Lin,HE Guang-Hua

Acta Agron Sin. 2013, 39(07):  1223-1230.  doi:10.3724/SP.J.1006.2013.01223

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A lesion mimic mutant temporarily designated as spl31 was discovered in the progeny of an excellent indica restorer line Jinhui 10 with seeds treated by ethyl methane sulfonate (EMS). The mutant phenotype was normal before the three leaf period but with yellow bad spots onleaves after the four leaf period. Along with the growth and development of the plant, the number of spots didn’t show significant difference, whereas the lesion area gradually enlarged and developed with tawny margin. As the spl31 matured, lesion spots interconnected between each other becoming a continuous piece, resulting in leaves’ death. The observation by transmission electronic microscope (TEM) demonstrated that most grana lamellae in spl31’s chroloplasts were irregularly stacked. Histochemical analysis revealed that deep blue stained cells presented discrete dietilution, illustrating that the lesion mechanism of spl31 may be spontaneously generated. The photosynthetic data showed that the mutation of spl31 had no effect onPSII. Furthermore, both 1000-grain weight and seed setting rate of the mutant decreased as compared with the wild type. Genetic analysis suggested that spl31 was controlled by a single nuclear recessive gene. Nipponbare was crossed with the spl31 and 621 mutational F₂ recessive plants were used for gene mapping. And finally, Spl31 locus was mapped on chromosome 12 near the centromere between ID104 and ID11 with physical distance of 383 kb and co-segregated with ID105.

AFLP and MSAP Analysis on Genetic Variation in Early Generations of Artificially Synthesized Brassica napus

ZHAO Zhi-Gang,FU Gui,DENG Chang-Rong,DU De-Zhi

Acta Agron Sin. 2013, 39(07):  1231-1239.  doi:0.3724/SP.J.1006.2013.01231

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In order to reveal pattern of genetic and epigenetic changes following allopolyploidization of A and C genomes in Brassica, AFLP (amplified fragment length polymorphism) was utilized to detect level of genome changes for S₀ plants of cross A (Qinghai Dahuang×Zhonghua Jielan) and S₀, S₁ plants of cross B (Qinghai Dahuang×Zhongchi Jielan). Moreover, MSAP (methylation sensitive amplification polymorphism) was utilized to detect level of methylation changes for S₀ plants of cross B. Five hundred and twenty three bands were amplified in S₀ plants of cross A with 16 pairs of primer, nine out of these bands amplified showed significant differences between S₀ and parents plants, mainly including deletion of seven parental restriction fragments and gain of two new fragments, accounting for 1.33% and 0.38% of total fragments, respectively. One thousand and ninety three bands were amplified in parental plants of B cross with 45 pairs of primer, only one from C genome out of these fragments lost in all S₀ plants, accounting for 0.09% of total bands. In 16 S₁ plants from the B9 plant, 10 out of 1092 bands amplified showed variations, consisting of the deletion of nine fragments from C genome and the gain of one new fragment. By MSAP approach, three loci with cytosine methylation changes were founded on A genome of S₀ plants of B cross, which accounted for 1.37% of loci detected. In addition, a plant with flower color mutation in S₀ generation of B cross was observed; we speculated that the flower color mutation was probably caused by genetic changes on C genome. This study provided theoretical informations for innovation of rapeseed germplasm by resynthesizing Brassica napus.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Characteristics of Plant Type Traits and Subspecies Characteristics in F₂ Generations of Cross Between Indica and Japonica Rice under Different Ecological Regions

JIN Feng,WANG He-Tong,XU Hai,JIANG Yi-Jun,ZHAO Ming-Zhu,YANG Li,XU Zheng-Jin,CHEN Wen-Fu,ZHENG Jia-Kui

Acta Agron Sin. 2013, 39(07):  1240-1247.  doi:10.3724/SP.J.1006.2013.01240

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Two F₂ populations, one derived from the cross between Wanlun 422 (indica) and Shennong 265 (japonica) named as F₂-A, the other derived from the cross between Luhui99 (indica) and Shennong 265 (japonica) named as F₂-B, were grown in Liaoning and Sichuan to analyze the effect of ecological environments on subspecies characteristics and their relationships with plant type traits. The result showed that subspecies characters in F₂ generations were continuously varied in different environments. Two populations were generally normal distribution in Sichuan, but obviously indica-like in Liaoning. The effects of environment on six traits of Cheng’s index were incompletely consistent. The ecological conditions had a significant effect on plant type traits. The plant height and panicle curvature increased significantly, but the panicle length, flag leaf length,flag leaf width and leaf angle decreased in Sichuan. Plant height in different subspecies had no obvious regularity in different regions. Flag leaf length was longer in indica (H) than in other types, but flag leaf angle had no significant difference in different subspecies and environments. Flag leaf width was changed with the cross combinations. Generally, panicle length reduced, but panicle curvature increased progressively from indica (H) to japonica (K) type. The subspecies characteristics were certainly related with plant type traits, but the correlation between them was not consistent in different cross combinations and environments.

Simple Evaluation Method of Tolerance to Salt at Seedling Stage in Soybean

JIANG Jing-Han,GUO Yong,CHANG Ru-Zhen,GUAN Rong-Xia,QIU Li-Juan

Acta Agron Sin. 2013, 39(07):  1248-1256.  doi:10.3724/SP.J.1006.2013.01248

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Salt stress seriously affected the production of soybean. Thus screening salt-tolerant soybeans is very important for developing salt resistant cultivars. The objective of this study was to establish a simple method for screening soybean varieties in response to salt stress. The seedlings of four salt-tolerant varieties and four salt-sensitive varieties were grown in vermiculite pouring with 0, 100, 200, and 250 mmol L^–1 NaCl solutions, adding each two days for three times. The SPAD was measured every day. The root, stem and leaf were sampled after eight days of treatment and Na⁺ content were measured by the atomic absorption spectrophotometer. The results indicated that it is easy to distinguish the level of salt tolerance based on foliar symptoms in both treatment of 200 mmol L^–1 and 250 mmol L^–1 NaCl. Under 250 mmol L^–1 NaCl stress, the Na⁺ content in leaf for salt-tolerant varieties was lower than that for salt-sensitive varieties. There was a significant correlation between Na⁺ content and SPAD in salt-sensitive varieties. This experiment established a convenient method of soybean salinity tolerance identification at seedling stage, using the seedlings grown in vermiculite with 200 mmol L^–1 and 250 mmol L^–1 NaCl treatment for eight days. It will facilitate the screening of germplasm, mechanism study and breeding selection on a large scale.

Effects of Soil Alkaline Hydrolyzed Nitrogen Concentration on Biomass and Nitrogen Accumulation Eigenvalues of Cotton after Initial Flowering

SONG Wei-Chao,LIU Chun-Yu,XU Jiao,SUI Ning,CHEN Bing-Lin,ZHOU Zhi-Guo

Acta Agron Sin. 2013, 39(07):  1257-1265.  doi:10.3724/SP.J.1006.2013.01257

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Two field experiments were conducted at Dongtai City (120°19' E, 32°52' N) and Dafeng City (120°28' E, 33°12' N) , Jiangsu province, in 2009 and 2010, severally. Six nitrogen rates (0, 150, 300, 375, 450, and 600 kg ha^–1) were set to study the effects of soil alkaline hydrolyzed nitrogen concentration (SAHNC) on biomass and nitrogen accumulation of cotton. The result showed that, the change of SAHNC could be simulated with a cubic function, biomass and nitrogen accumulation of cotton could be simulated with logistic formula; average rate and duration of the SAHNC’s speedy reducing had significant correlation with the biggest rate and duration of speedy accumulation period of cotton’s biomass and nitrogen. Under the nitrogen applied level of 375 kg ha–1, the SAHNC speedy reducing had optimal average rate and duration, cotton plant had optimal biomass and nitrogen accumulation eigenvalues, and had the highest fiber yield and optimal fiber qualities. Too high or too low nitrogen application was not benefit for biomass and nitrogen accumulation of cotton. Therefore, optimal nitrogen applied level and nitrogen applied strategy can adjust the dynamic change of SAHNC, and be beneficial for optimizing biomass and nitrogen accumulation eigenvalue and the lint yield and qualities after initial flowering.

Yield Formation Characteristics of Transgenic Rice Strains with Different Protein Contents in Grains

WANG Kang-Jun,XIONG Yi-Wei,GE Li-Li,ZHANG Hao,WANG Zhi-Qin,YANG Jian-Chang,LIU Li-Jun*

Acta Agron Sin. 2013, 39(07):  1266-1275.  doi:10.3724/SP.J.1006.2013.01266

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Relationship between protein content (PC) in grains and grain yield in rice has not been clearly understood. Nipponbare and its five transgenic strains with different PCs in grains were used in the study to investigate their yield formation characteristics under the condition of field cultivation. There were two main results: (1) Under the same nitrogen amount, grain yields were lower in strains with higher PC in grains. Filled grain rate was very significantly and negatively correlated with PC in grains. With an increase in N fertilizer, PC in grains and grain yield significantly increased and the increase in yield was mainly dependent on the increase in panicle number and grains per panicle. (2) Under the same nitrogen amount, the strains with higher PC had less dry matter accumulation before heading stage, shorter functional period and lower photosynthetic rate of flag leaves after heading stage and lower apparent translocation amounts of dry matter and non-structure carbohydrates (NSC) from stems to grains during grain filling stage, leading to lower filled grain rate, which is the possible physiological reason for lower yield in those strains.

Changes of Hormones in Cultivars and Wild-Type Varieties of Rehmannia glutinosa Libosch.

LI Xian-En,SUN Peng,QI Jian-Jun,ZHOU Li-Li,WANG Shao-Hua

Acta Agron Sin. 2013, 39(07):  1276-1283.  doi:10.3724/SP.J.1006.2013.01276

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The formation and development of tuberous roots is related to plant endogenous hormones. We determined the contents of IAA, ZR, GA and ABA in leaves and roots of two cultivars and two wild-type varieties of Rehmannia glutinosa during the growth periods and compared their developmental changing trends between cultivars and wild-type varieties of Rehmannia glutinosa. The results showed that the contents of IAA, ZR, and ABA in leaves of cultivated Rehmannia glutinosa were higher than those of wild-type varieties and their changes in both cultivated and wild type of R. glutinosa displayed the same single-peak curves during the growth periods, they were all increased gradually at the elongation and rapid enlargement stages of roots and then decreased gradually. There was no significant developmental change in GA content in the leaves of both cultivated and wild-type varieties. Hormone contents in roots of cultivars had quite different developmental changes from those of wild-type varieties: The contents of IAA, ZR, and ABA in the cultivars presented the changing trend of single-peak curves during root growth periods while GA content increased rapidly in root enlargement stage. There was no much developmental change in IAA and GA contents in roots of wild-type varieties. ZR content decreased gradually with the root development in wild-type varieties. ABA content changed in roots of wild-type varieties displayed a single-peak curve which was much lower than that of the cultivars. This different developmental changes of hormone contents in rehmannia roots between cultivars and wild-type varieties indicated that the development of the rehmannia tuberous roots is affected by synergitic effects of several hormones and that IAA and ZR act on the initiation of tuberous roots, whereas GA and ABA play a more important role in root enlargement and thickening.

Post-Anthesis Photosynthetic Assimilation and the Changes of Carbon and Nitrogen in Different Varieties of Spring Maize

SUN Xue-Fang,DING Zai-Song,HOU Hai-Peng,GE Jun-Zhu,TANG Li-Yuan,ZHAO Ming

Acta Agron Sin. 2013, 39(07):  1284-1292.  doi:10.3724/SP.J.1006.2013.01284

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Dry matters production after anthesis is very important for maize yield. To further clear its role in super high yield condition (high density with ample water and fertilizer supply), we compared yield components in three cultivated varieties, including Denghai661 (DH661), Zhongdan 909 (ZD909) and 970. According to the theory of yield performance, the post-anthesis yield performance parameters were analyzed. The changes of net photosynthetic rate, the contentsof chlorophyll, soluble sugar, starch, total C and N were measured in the ear leaf. The results showed thatthere were significant differences in the yield among three varieties. Varieties with higher yield (DH661 and ZD909) had higher kernel weight per ear, while DH661 had more grains per ear (466.7) and ZD909 had higher 1000-kernel weight (392.7 g).The post-anthesis dry matter production and its partitive ratios in grains were both higher in the two varieties with higher yield. Yield performance analysis showed that the mean leaf area index (mLAI) and leaf area duration (LAD) were significantly and positively correlated with post-anthesis dry matter production and yield. The chlorophyll, total carbon and total nitrogen content decreased slowly and C/N ratio increased slowly in the two varieties with higher yield. The net photosynthetic rate (P_n) was relatively higher in the ear leaves in the whole grain filling stage. The photosynthate not only supplied to kernels but also stored as starch in leaves at the early phase of grain filling. Only when P_n declined at late phase of grain filling the accumulated starch began to degrade for the kernel filling. These results indicated that the balance between carbon and nitrogen metabolism, and slowing down the photosynthate decrease in ear leaf are responsible for maintaining higher mLAI and LAD, resulting in higher yield.

Interference of Different Morphological Types and Allelopathic Rice Materials with Three Principal Paddy Weeds

XU Zheng-Hao,XIE Guo-Xiong,ZHOU Yu-Jie,GAO Shen

Acta Agron Sin. 2013, 39(07):  1293-1302.  doi:10.3724/SP.J.1006.2013.01293

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The present study was carried out to investigate the allelopathic abilities of the tested rice materials on the three main paddy field weeds using split design with three replications. Two weed planting patterns, using relay transplanting three weeds, Echinochloa crs-galli, Juncellus serotinus, and Monochoria vaginalis, and without weed infestation, were taken as two main treatments, along with ten different morphological type and allelopathic rice materials as split treatments. The results showed that the superb allelopathic rice material, Xiayitiao, had the strongest ability to suppress the aboveground dry weight of barnyardgrass. Early indica hybrid rice Zhong 9A/602 and early rice Zaoxianzhe 101, also exhibited inhibitory effect on the aboveground dry weight of barnyardgrass. Rice allelopathic material, TN1, having allelopathic effect on several weeds, Echinochloa crs-galli, Trianthema portulacastrum, Heteranthera limosa and Ammannia coccinea, also could control the aboveground dry weight of barnyardgrass effectively. The allelopathic effects of different morphological as well allelopathic rice materials on plant height of barnyardgrass were not significantly different. This indicated that rice materials could inhibit effectively the aboveground dry weight of barnyardgrass mainly by suppressing its tillering ability. Rice allelopathic material, TN1, could not control the growth of Juncellus serotinus effectively, however, rice material, Zhongzao 22 had the strongest ability to control the growth of the weed effectively among the tested rice materials. Rice material, Zaoxianzhe 101, along with the superb allelopathic rice material, Xiayitiao, also suppressed Juncellus serotinus effectively while rice material, Zhongzao 22, could not inhibit the weed growth effectively, despite of conferring taller plant height. Early indica hybrid rice, Zhong 9A/602, and early indica rice Zaoxianzhe 101, along with rice allelopathic materials, Xiayitiao and IR644-1-633-1-1 showed significant inhibitory effects on Monochoria vaginalis, while rice allelopathic material, Gumei 2, and rice material, Zhongzao 27, did not suppress the weed significantly. The inhibitory effects of different morphological and allelopathic rice materials on the overall aboveground dry weight of the three weeds were significantly different. The superb allelopathic rice material, Xiayitiao, reduced the aboveground dry weight of the three weeds more than 50%, which was significantly different from those of four other allelopathic rice materials, IR644-1-63-1-1, PI312777, TN1, and Gumei 2 who did not show significantly adverse effects. Rice materials, early indica hybrid rice Zhong 9A/602 and early indica rice Zaoxianzhe 101 reduced the total aboveground dry weight of the tested weeds over 40% compared with the control. The plant height, number of efficient panicle, panicle length and total spikelets per panicle of rice materials showed a significant difference between treatments of weed competition and without weed infestation. The seed setting rate and 1000 grain weight were not remarkably different between treatments of weed competition and without weed disturbance. Compared with the control without weed interference, the plant height of elite allelopathic rice material Xiayitiao increased 3.64% under the disturbance of three weeds, while on the contrary, those of indica hybird rice Zhong 9A/9791 and allelopathic rice materials IN1 and Gumei 2 decreased more than 10%. The efficient panicles of all of the rice materials tested under weed competition reduced significantly than those of the control, among them those of TN1, Gumei 2, PI312777, Zhongzao 22, Zhongzao 27, and Zhong 9A/602 decreased more than 50%. The peculiar rice allelopathic material Xiayitiao only showed 16.86% decreases. All kinds of weed competition decreased panicle number of the tested rice materials significantly; suggesting the main reason for declining rice productivity.

RESEARCH NOTES

Effects of Soil Arsenic on Soybean Main Traits and Chlorophyll Content at Different Growing Stage

LI Hai-Bo,YANG Lan-Fang,LI Ya-Dong

Acta Agron Sin. 2013, 39(07):  1303-1308.  doi:10.3724/SP.J.1006.2013.01303

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Arsenic is ubiquitous in environment and has high toxicity to animal and plant. Investigating the effects of arsenic on plant growth is important for the recognition of the toxic mechanism of arsenic to plant and the food safety. To understand the relationship between soil arsenic pollution and plant growth, we conducted a soil pot experiment using a soybean variety with adding different amounts of arsenic into soil, in which the soybean growth condition was observed and the plant height, chlorophyll content at podding and grain filling stages and the biomass after harvest were determined. The results showed that visible symptom of arsenic toxicity to soybean was dwarfing of plants, dark green and crimpled leaves, retarded maturity when soil arsenic addition was up to 50 mg kg^–1. The soybean plant height decreased and the soybean biomass significantly reduced when high soil arsenic contents. The soybean plant height, soybean stem biomass, aerial part biomass, grain yield and the total soybean biomass decreased by 45.0%, 36.6%, 44.6%, 56.1%, and 43.4%, respectively, in the treatments of 100 mg kg^–1 of arsenic. High soil arsenic amounts increased the biomass ratios of roots to aerial parts and stem grains to aerial parts, but decreased the ratios of grains to aerial parts, grains to stems and grains to total biomass. Soil arsenic amounts had no significant effects on chlorophyll content in soybean leaf but decreased the ratio of Chl a to Chl b at podding stage. At grain filling stage, 50 and 100 mg kg^-1 arsenic treatments increased 120.4% and 96.1% of Chl a, 112.2% and 91.5% of Chl b, 117.8% and 94.5% of total chlorophyll and 104.4% and 83.7% of carotenoid content, respectively. High soil arsenic amounts reduced the ratio of chlorophyll content at podding stage to that at grain filling stage significantly. In conclusion, high soil arsenic amounts are toxic to soybean growth, affect the allocation of soybean biomass, and decrease the biomass of aerial parts and grains yield. The important reason of the retardation of soybean maturity is the constitutional alteration of chlorophyll in soybean leaf and the relative increment of chlorophyll content in soybean leaves during later growing stage by high soil arsenic amounts.

Genetic Evaluation of Major Traits in Fuzzless Upland Cotton Germplasm

SUN Ya-Li,HE Shou-Pu,SUN Jun-Ling,PAN Zhao-E,JIA Yin-Hua,PANG Bao-Yin,Du Xiong-Ming

Acta Agron Sin. 2013, 39(07):  1309-1318.  doi:10.3724/SP.J.1006.2013.01309

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A total of 102 fuzzless seed upland cotton varieties (G. hirsutum) as female parents were crossed with genetic standard line TM-1 (as male parent) to analyze the main traits in the F₁ population with random blocks design with three replications. The results showed that there were significant differences among eleven agronomic traits between different parents, and the difference of yield traits (plant height, fruit branch number, boll number, boll weight, lint percentage, and seed index) was higher than that of fiber quality traits (length, strength, micronaire, uniformity, elongation rate), especially for lint percentage, boll number, except for fruit branch number, micronaire and elongation rate, the mean values of other traits in parent populations were lower than those in F₁ populations, however, the coefficient of variation in fuzzless seed parents was higher than that of F_1. The heterosis including mid-parent heterosis and heterobeltiosis highly varied in different varieties. Some traits of some varieties with negative heterosis showed inferior descendants, The mid-parent heterosis and heterobeltiosis in fiber quality traits showed negative correlation with fuzzless rate, but yield traits showed positive correlation with fuzzless rate, indicating that the heterosis could be applied for fiber quality improvement but might be limited for the yield improvement, No significant correlation was found between genetic similarity coefficients based on SSR markers and heteroses in all traits, indicating that it is difficult to predict heterosis by using genetic background similarity of parents in fuzzless cotton breeding.

Effects of Betaine on Chloroplast Protective Enzymes and psbA Gene Expression in Wheat Seedlings under Drought Stress

HOU Peng-Fei,MA Jun-Qing,ZHAO Peng-Fei,ZHANG Huan-Ling,ZHAO Hui-Jie,LIU Hua-Shan,ZHAO Yi-Dan,WANG Yue-Xia

Acta Agron Sin. 2013, 39(07):  1319-1324.  doi:10.3724/SP.J.1006.2013.01319

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With the purpose of revealing the effect of exogenous glycine betaine (GB) on wheat seedlings, Aikang 58 was used as the experimental material, which has the characteristics of high yield and drought resistance. The leaves were sprayed with 0.1, 1.0, and 10.0 mmol L⁻¹ of GB during four-leaf stage, respectively, while the root was applied by 30% polyethylene glycol (PEG-6000) to simulate the drought environment. The effects of exogenous GB treatment on the parameters of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) activities, superoxide anion radicals () production rate, malondialdehyde (MDA), chlorophyll content, and relative water content (RWC)under drought stress were tested three days after treatment. Simultaneously, the relative transcriptional expression of psbA inchloroplast was determined by real time PCR assay. The results showed that drought stress obviously decreased the RWC and chlorophyll content of wheat leaves, reduced activities of SOD, CAT, and POD, increased MDA content and the production rate of reactive oxygen species, and suppressed psbA expression. Nevertheless, such stress reactions were alleviated by exogenous GB treatment, and this regulation effect showed a great correlation with GB concentration. These results indicated thatexogenous GB could remove excess reactive oxygen, and retard the decrease of RWC and chlorophyll content by regulating antioxidant enzyme activities in wheat chloroplast under drought stress, enhance the transcriptional level of psbA gene, accelerate the turnover of D1 protein in wheat chloroplast, and finally improve the drought resistance in wheat.

Effects of Abiotic Stress on Yield Traits of Maize Hybrids and Their Parental Inbred Lines

YANG Xiao-Qin,ZHANG Ren-He,XUE Ji-Quan,TAI Shu-Jing,ZHANG Xing-Hua,LU Hai-Dong,GUO Yan-Ping,GUO De-Lin

Acta Agron Sin. 2013, 39(07):  1325-1329.  doi:10.3724/SP.J.1006.2013.01325

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The field experiments were conducted to study the changes of grain yield and concerned physiological traits in stress-tolerant maize variety Zhengdan 958 and its parental inbred lines (Zheng 58 and Chang 7-2), as well as stress-sensitive maize variety Shaandan 902 and its parental inbred lines (K22, K12) under different treatments of density (45 000 and 75 000 plants ha⁻¹), nitrogen application (112.5 and 337.5 kg ha⁻¹), and irrigation (normal irrigation and controlling water at prophase). The results showed that there were little differences in yield, mean leaf area index after anthesis, mean SPAD after anthesis, post-anthesis dry matter accumulation and harvest index between Zhengdan 958 and Shaandan 902 under resource-replete conditions (low density, high nitrogen and normal irrigation). But there were great differences in all traits (besides harvest index) between Zhengdan 958 and Shaandan 902 under abiotic stress (high density, low nitrogen and drought stress), with much higher values in Zhengdan 958 than in Shaandan 902. Compared with Shaandan 902, mid-parent values of leaf area index, SPAD, post-anthesis dry matter accumulation and grain yield of Zhengdan 958 under abiotic stress (high density, low nitrogen and drought stress) increased by 45%, 36%, 51%, and 45%, respectively, and heterosis of Zhengdan 958 increased by 18%, 9%, 28%, and 22%, respectively. The mid-parent value of yield was much higher than heterosis of yield and both of them were higher in Zhengdan 958 than in Shaandan 902. So the maize variety Zhengdan 958 showed greater tolerance to abiotic stress which was mainly inherited from its parental inbred lines. Higher SPAD and LAI after anthesis contributed to post-anthesis dry matter accumulation, resulting in higher yield and higher stress tolerance.