Table of Content

12 March 2012, Volume 38 Issue 03

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REVIEW

Structure, Function, and Co-evolution of Rice Blast Resistance Genes

Moytri ROYCHOWDHURY, JIA Yo-Lin,Richard D. CARTWRIGHT

Acta Agron Sin. 2012, 38(03):  381-393.  doi:10.3724/SP.J.1006.2012.00381

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Rice blast disease caused by the fungal pathogen Magnaporthe oryzae is one of the most destructive rice diseases worldwide. Resistance (R) genes to blast encode proteins that detect pathogen signaling molecules encoded by M. oryzae virulence (AVR) genes. R genes can be a single copy gene or a member of clustered gene families that have evolved through duplication and diversification. Recent advances in blast R gene cloning and subsequent characterization have provided useful insights into R gene mediated signaling transduction pathways. This review summarizes recent advances in cloning and characterization of blast R genes, and presents an update on evolutionary dynamics of R proteins, their interaction and co-evolution with the signaling molecules encoded by the AVR genes, and potential implications for crop protection.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Pedigree Analysis of Photoperiod-thermo Sensitive Genic Male Sterile Rice

SHI Hua-Min, FU Ya-Ping, LIU Wen-Zhen, SUN Zong-Xiu, HU Guo-Cheng

Acta Agron Sin. 2012, 38(03):  394-407.  doi:10.3724/SP.J.1006.2012.00394

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A great progress has been made in two-line hybrid rice in China. Up to 2010, a total of 427 two-line hybrid combinations (cultivars) had been registered. In recent years, two-line hybrid rice has become an important type in rice production in China. Photoperiod-thermo sensitive genic male sterile (PTGMS) lines are the basis of two-line hybrid rice. In this paper, the relationship of 130 PTGMS lines used as parents of registered hybrid combinations and/or with the right of protection of new varieties was analyzed, and 126 of 130 PTGMS lines that the relationship defined were traced back to their original PTGMS lines as a starting point. The pedigree of the 73 PTGMS lines used for producing hybrid combinations with large scale planting and/or the right of protection of new varieties was analyzed in detail, and the breeding methods of the 126 PTGMS lines were analyzed. The relationship between the photoperiod-thermo response type and the pedigree of the PTGMS lines was discussed. We also proposed that selecting the proper PTGMS materials by pedigree analysis is as important as photoperiod and temperature controlling for studying the molecular mechanism of photoperiod-thermo response in PTGMS lines. Open sharing of the PTGMS resources has the great significance for accelerating the breeding of new practical PTGMS lines and minimizing the adverse environmental impact on seed production of two-line hybrid rice.

Mapping of the Resistant Gene to Rice Blast in the Dual Purpose Genic Male Sterile Rice, LongS

WANG Jian-Long, TUN Li-Qun, LIU Jian-Feng, Dai-Liang-Yang, LIU Xiong-Lun, XIAO Ying-Hui, XIE Gong-Jun, LIU Qun-En, LI Ting, JIA Xian-Yong, WANG Guo-Liang, YUAN Long-Beng

Acta Agron Sin. 2012, 38(03):  408-415.  doi:10.3724/SP.J.1006.2012.00408

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LongS is a dual purpose genic male sterile rice with broad-spectrumresistance to rice blast. The objective of the present study was to identifythe resistance spectrumto rice blast, to analyze thegenetic behavior ofresistance gene, and tomap the major resistancegenes in LongS. LongS had a resistance frequency of 100% inoculatedwith 41strainsofMagnaporthe oryza. Population geneticanalysis showed that theresistance genes in LongSexhibited dominant inheritance, the genetic model of R gene varied depend on the strainsof Magnaporthe oryzae. The main-effect resistant gene to rice blast was fine mapped, by using the bulk segregant analysis (BSA) and recessive class analysis (RCA) methods, with the F₂ population derived from the resistant parent of LongS and the susceptible parent of Nipponbare. Asingle resistant gene to the race of 318-2 locatedon the interval flanked by the SSRmarkersof M1 and M2with a genetic distance of 1.3 cM onchromosome 9 were adjacent to the broad-spectrum blast resistance gene, Pi5. Both of the resistance spectrum and resistant frequency of LongS, however, were significantly different to those of resistant gene of Pi5 and Pii. In conclusion, the major-effect resistant gene identified in this study may be a new broad-spectrum blast resistance gene. The DNA markers linked to the new R gene identified in this study should be useful for marker-aided breeding of blast-resistant rice cultivars.

Doubling Efficiency of Maize Haploids Treated by Different Herbicides

HUI Guo-Qiang, DU He-Wei, YANG Xiao-Gong, LIU Guang-Hui, WANG Zhen-Tong, ZHANG Yi-Rong, ZHENG Yan-Ping,YAN Jian-Bing, CHANG Ming-Tang, LI Jian-Sheng

Acta Agron Sin. 2012, 38(03):  416-422.  doi:10.3724/SP.J.1006.2012.00416

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The objective of this investigation was to explore a new technology of doubling maize haploids using herbicides. Maize haploids used in this research were induced from three hybrids: Pioneer 335, N-D 4, and 8607×8609. Herbicides, Amiprophos-methyl (APM), pronamide and trifluralin with the concentration of 20, 40, 80, and 160 μmol L^-1, respectively, were used for doubling the haploids by drop into the interior leaf whorls of the haploid from the 3-leaf stage to the 5-leaf stage. The haploid plants having pollens were self-pollinated during the pollen shedding stage and the doubling rates of three herbicides were investigated at the mature stage. Both chromosome number of root tip cells and pollen fertility among sampling haploid plants were analyzed. The results showed that all three herbicides had effects on doubling haploids with the rates of 3.42% and 26.32%.The doubling rates of haploids from Pioneer 335, N-D 4 and 8607×8609 were 4.29–26.32%, 3.85–20.81%, and 3.42–17.61%. The doubling rates of haploids from Pioneer 335, N-D 4 and 8607×8609 teated by 80 μmol L^-1 APM were 25.02%, 20.13%, and 14.99% respectively. The results showed that there were significant differences between Pioneer 335 and N-D 4, Pioneer 335 and 8607×8609, and N-D 4 and 8607×8609 for the doubling rates. To sum up, APM, pronamide and trifluralin all have significant effect on doubling maize haploids and the sensitivity of maize haploids from diverse sources to the same herbicide is different.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genetic Analysis and Molecular Mapping of a Rolled Leaf Gene RL₁₃ in Rice (Oryza sativa L.)

TIAN Xiao-Qiang, SANG Xian-Chun, ZHAO Fang-Ming, LI Yun-Feng, LING Yang-Hua, YANG Zheng-Lin, HE Guang-Hua

Acta Agron Sin. 2012, 38(03):  423-428.  doi:10.3724/SP.J.1006.2012.00423

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Rolled 1eaf mutants are good materials rice in breeding for leaf and plant type. A rolled 1eaf mutant rl₁₃ was derived from an EMS-treated mutation in an indica line (Jinhui 10). The chlorophyll content of rl₁₃ was significantly higher than that of wild type Jinhui10. There was a highly significant difference in the curl of the three functional mutant leaves compared with those with wild-type. However, there were no significant differences between the three functional mutants. Through the analysis of paraffin, mesophyll cells per layer in rl₁₃ thinned, wild-type cells contain a large bubble into two similar size vesicular cells of mutants, which resulted in the character of rolled leaf. We made the combination of Xinong1A/rl₁₃ to establish genetic population for genetic analysis, the results confirmed that the mutant trait was controlled by a single recessive nuclear gene. In the F₂, the gene of the rolled leaf trait was mapped between two SSR markers, RM276 and SWU6-1, with distances of 1.1 cM and 0.2 cM, respectively.

Mapping of a Short Root-Related Gene OsKSR2 in Rice (Oryza sativa L.)

LUO Li-Li, SHI Jun-Ying, XIANG Xian-Bo, DING Wo-Na, ZHU Shi-Hua

Acta Agron Sin. 2012, 38(03):  429-435.  doi:10.3724/SP.J.1006.2012.00429

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Theroot system of plant plays an important role in supporting plants and uptaking nutrients and water in soil. In this study, a rice mutant with significantly short roots was isolated from an EMS (ethyl methane sulfonate)-generated mutant library of Kasalath and named as Osksr2(Oryza sativa kasalath short root 2). Osksr2 showed a dwarf phenotype and the elongation of primary roots, adventitious roots and lateral roots in the mutant was severely impaired. Genetic analysis indicated that the mutant phenotype was controlled by a single recessive nuclear gene, and named as OsKSR2. To map OsKSR2, we generated an F₂ population by crossing Osksr2 with Nipponbare wild type. By using the published SSR markers and newly designed STS markers, OsKSR2 was mapped to a 101 kb region between the markers S27887 and S27988 on chr.8. Within this region there were seventeen predicted genes, and none of them had been reported to be involved in root development. The study will be helpful for the cloning of OsKSR2 and characterization of the molecular mechanism of root elongation in rice.

Genetic Analysis of Broad-grown Wheat Cultivar Bainong AK58 and Its Sib Lines

LI Xiao-Jun, HU Tie-Zhu, LI Gan, JIANG Xiao-Ling, FENG Su-Wei, DONG Na, ZHANG Zi-Yang, RU Zhen-Gang,HUANG Yong

Acta Agron Sin. 2012, 38(03):  436-446.  doi:10.3724/SP.J.1006.2012.00436

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Bainong AK58 has been growing widely in Southern Huang-Huai Rivers Facultative Winter Wheat Region in China. Bainong AK58 and its two sib lines, Fengshou 60 and Bainong 4330, were evaluated based on agronomic traits, high-molecular-weight glutenin subunit (HMW-GS), protein content, and 657 SSR markers distributing across the whole genome of wheat. Bainong AK58 had more spikelets, grains per spike, spikes per plant, and larger 1000-grain weight than the sib lines, and the number of sterile spikelets in Bainong AK58 was less than that in Fengshou 60 and Bainong 4330. Bainong AK58 had the same HMW-GS composition (1, 7+8, 5+10) as its parent Zhengzhou 8960, whereas Fengshou 60, Bainong 4330 and their parent Wenmai 6 had the identical HMW-GS composition (1, 7+9, 5+10). SSR data revealed that the rates of genetic information inherited from parents Zhoumai 11, Wenmai 6, and Zhenzhou 8960 were 47.4%, 28.9%, and 23.7% for Bainong AK58, and 47.9%, 30.7%, and 21.4% for Fengshou 60, respectively. This indicated that Bainong AK58 and Fengshou 60 were most similar to parent Zhoumai 11. Bainong 4330 inherited nearly equal genetic components from the three parents (33.1%, 32.4%, and 34.6%, respectively). The genetic contributions from the three parents to the three sib lines were unbalanced on either genomic level or chromosomal level. Furthermore, Bainong AK58 had 40 specific SSR loci compared to its sib lines, which were distributed on chromosomes 1A, 4A, 5A, 6A, 1B, 4B, 5B, 6B, 7B, 1D, 2D, 3D, and 7D. Most of the loci were related to known genes controlling important traits, such as yield and resistance to diseases. These loci might play an important role on the broad planting of Bainong AK58.

Molecular Mapping and Identification of QTLs for Fiber Micronaire on Chromosome 7 from Gossypium klotzschianum

XU Peng, ZHU Jing, ZHANG Xiang-Gui, NI WAN-Chao, XU Yang-Jun, SHEN Xin-Lian

Acta Agron Sin. 2012, 38(03):  447-453.  doi:10.3724/SP.J.1006.2012.00447

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G. klotzschianum, carrying the elite alleles, is a diploid species of D genome originated from Galapagos Island, harboring the lethal genes to cause inconsistency of apical bud growth. In this research, we overcame the obstacle and established a BC₁F₂ population derived from (Simian2× G. klotzschianum) ×Simian2 (G. hirsutum). The SSR marker NAU1362 on chromosome 7 showed significant correlation with micronaire value by single marker analysis. The BC₂F₃ and BC₂F₄ populations were developed from the cross between BC₁F₂ individuals containing target segments of chromosome 7 from G. klotzschianum and recurrent parent Simian2. The software Cartographer (V2.5) and the composite interval mapping were further employed to identify quantitative trait loci (QTL) associated with fiber micronaire in two generations. The fiber micronaire QTL qFMIC-7-1 identified in BC₁F₂ population was confirmed in BC₂F₃ and BC₂F₄, which explained 9.0% and 8.8% of the phenotypic variance, respectively. The G. klotzschianum allele decreased the fiber micronaire value. Another micronaire QTL qFMIC-7-2 on chromosome 7 was also detected in BC₂F₃ and BC₂F₄ generations with phenotypic variance of 3.7% and 4.7%, respectively. Simian2 was genotyped as decreased micronaire value. This study provides valuable resources for effectively utilization of potential elite genes from G. klotzschianum.

Development of Near-isogenic Lines with Different Wheat Wx Genes and Their Effects on Amylose Content and Noodle Quality

YU Chun-Hua, BIE Tong-De, WANG Cheng, ZHANG Xiao, WU Rong-Lin, CHENG Xiao-Ming, WANG Can-Guo, ZHAO Yun, CHENG Shun-He

Acta Agron Sin. 2012, 38(03):  454-461.  doi:10.3724/SP.J.1006.2012.00454

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Granule bound starch synthase (GBSS), controlled by Wx gene, is a key enzyme for amylose synthesis. Wheat has three homologous Wx genes located on 4AL, 7BS, and 7DS. The purpose of this study was to understand the effects of wheat Wx genes on amylose content and noodle sensory quality. A waxy wheat line, Caiwx (aabbdd), was used as a donor parent for Wx null alleles and a high yield cultivar, Yangmai 01-2 (AABBDD), was used as a recurrent parent. A BC₉F₂ population was constructed through successive backcrossing assisted by pollen staining with I₂-KI solution. Eight homozygous near isogenic lines (NILs) with different Wx gene combinations (AABBDD, AABBdd, AAbbDD, AAbbdd, aaBBDD, aaBBdd, aabbDD, aabbdd) were then identified by STS markers of Wx genes and GBSS isoenzyme markers in the BC₉F₄ generation.The amylose contents and noodle sensory quality of these NILs were evaluated. The amylose contents of the NILs ranged from 0.9% to 24.8% with significant difference among lines. There was a regularly descending trend of amylose content in genotypes as normal wheat (AABBDD) > single null allele genotypes (aaBBDD, AAbbDD, and AABBdd) > double null allele genotypes (aabbDD, aaBBdd, and AAbbdd) > waxy wheat (aabbdd). Genotype aaBBdd had the highest amylose content in the double-null-allele group, and genotype AAbbDD had the lowest amylose content in the single-null-allele group. This indicated that Wx-B1 allele plays the most important role in amylosesynthesis. It was also found that the amylose content reduction did not follow a directly linear relationship when the null allele number increased. Thus, we inferred that there exits gene interaction among different Wx alleles. The result of noodle sensory quality evaluation showed that there were significant differences among the eight NILs. All the noodle sensory scores of waxy wheat (aabbdd) on color, appearance, firmness, stickiness, as well as the total score, were the lowest among the eight NILs. The single null genotypes performed better noodle sensory quality than the other genotypes and the recurrent parent Yangmai 01-2. In the single-null-allele group, the aaBBDD genotype showed the best noodle sensory quality (scored 87.4). Noodles made of flour of aaBBDD genotype were as good as those made of Xuehua flour, a kind of high-quality flour for noodle-making. However, the other seven genotypes and Yangmai 01-2 had significantly lower noodle scores than Xuehua flour. Therefore, it is feasible to develop wheat cultivars with high noodle quality through genetic manipulation on Wx gene.

Analysis of Protein Expression at Different Microspore Development Stages in Wheat Cultivar Shaannong 138

BI Hui-Hui, YANG Hua-Rui, MA Jun-Hui, LIU Lu-Xiang, WANG Cheng-She, XU Xi-Tang, ZOU Shu-Fang, XIE Yan-Zhou

Acta Agron Sin. 2012, 38(03):  462-470.  doi:10.3724/SP.J.1006.2012.00462

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To understand the metabolic mechanism of wheat anther development, we analyzed the holoprotein of Shaannong 138 at mid-late mononuclear pollen and binuclear pollen stages using two-dimensional electrophoresis technique. More than 450 clear protein spots were identified, including 26 differentially expressed protein spots. We selected 14 protein spots with expression difference at least two times for further separation by means of matrix-assisted laser desorption time of flight mass spectrometry peptide mass fingerprint analysis (MALDI-TOF-MS) in isoelectric point (pI) of 4–7. After indexing database NCBInr using software Mascot, we identified 11 significant protein spots. These protein spots were classified into several groups based on function, i.e., UDP-glucose pyrophosphorylase (one spot), chlorophyll antibody-binding protein (one spot), pentatricopeptide repeat protein PPR566-6 (one spot), cysteine protease inhibitor (one spot), ubiquitin (one spot), S-adenosyl-L-cysteine hydrolase (two spots), oxygen-enhanced proteins (two spots), and putative proteins (two spots). These proteins are involved in glycometabolism, protein degradation, cell defense, and some other metabolic processes.

Selection of Reference Genes from Sesame Infected by Macrophomina phaseolina

LIU Chi-Ming, LIU Hong-Yan, TIAN Bao-Ming

Acta Agron Sin. 2012, 38(03):  471-478.  doi:10.3724/SP.J.1006.2012.00471

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Stem rot caused by Macrophomina phaseolina (Tassi) Goid. is the most important disease in sesame, worldwide, the use of sesame cultivars resistant to stem rot provides an effective, economical, and environmentally friendly method to control the disease. The study on sesame defense response plays important roles in breeding resistant cultivars, andqRT-PCRwas an important method in studying plant defense response. In order to select the proper reference genes which can normalize expression of the target gene in sesame induced by Macrophomina phaseolina, nine genes 18S rRNA, NADHD, GAPDH, β-actin, α-tubulin, UBQ5, RPL4, eIF4A, and eEF1α, was analyzed by qRT-PCR. Among the nine genes, last seven were designed using CodeHop. BestKeeper, NormFinder and GeNorm analyses showed that UBQ5, eIF4A and α-tubulin were the top three optimum choices while eEF1α varied greatly. The analysis revealed that the three most stable genes UBQ5, eIF4A, α-tubulin were enough to obtain an accurate result when using multiple genes as control.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Relationship among Amylose Content, Starch Pasting and Ethanol Fermentation in Sweetpotato Varieties for Starch Use

SUN Jian, YUE Rui-Xue, CHOU Fu-Xiang, XU Fei, ZHU Gong

Acta Agron Sin. 2012, 38(03):  479-486.  doi:10.3724/SP.J.1006.2012.00479

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Fifteen starch-based sweetpotato varieties were used to test amylose contents (AC), starch pasting properties and ethanol fermentation characteristics, and analyze the difference and relationship among them. The results indicated that there were significant differences among dry matter content, starch content and AC of different sweetpotato varieties, and AC was significantly correlated to dry matter content and starch content. Differences presented among pasting properties in different varieties of sweetpotato, and the relationship among RVA eigenvalues was close. There were significant differences among ethanol fermentation characteristics of different sweetpotato varieties, and ethanol content was significantly correlated to fermentative strength. There were no significant correlation between AC and RVA eigenvalues, but pasting temperature (PT) was positively correlated to dry matter content (r=0.661, P<0.01) and starch content (r=0.670, P<0.01). AC was positively correlated to ethanol content (r=0.653, P<0.01) and fermentative strength (r=0.698, P<0.01), but not significantly correlated to fermentation efficiency and fermented mash viscosity. Fermented mash viscosity was negatively correlated to breakdown (BDV) (r= –0.563, P<0.05) and positively correlated to setback (SBV) (r=0.639, P<0.05), but ethanol content, fermentation efficiency and fermentative strength were not significantly correlated to RVA eigenvalues. The cluster analysis showed that 15 varieties were divided into three parts: the first part featured higher AC and BDV, the second part had highest AC and lowest BDV, and the third part had lowest AC and highest BDV. Consequently, AC and BDV could be used as the indexes to evaluate the ethanol fermentation characteristics of sweetpotato, and the sweetpotato with higher AC and BDV was the breeding targets for fuel ethanol.

Effect of Potassium Application Methods on Antioxidant Enzyme Activities, Yield and Potassium Use Efficiency of Cotton

LI Zong-Tai, CHEN Er-Ying, ZHANG Mei-Ling, ZHAO Qiang-Long, XU Xiao-Long, JI Hong, SONG Xian-Liang, SUN Xue-Zhen

Acta Agron Sin. 2012, 38(03):  487-494.  doi:10.3724/SP.J.1006.2012.00487

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With application of modern cotton (Gossyium hirsutum L.) varieties including Bt (Bacillus thuringiensis) transgenic cotton, premature senescence caused by potassium (K) deficiency has become an important problem in cotton production in the Yellow River Valley of China. Field trialswere conducted in 2009 and 2010using Lumianyan 28. Four treatments consisting of no potassium (CK), basal application of potassium sulfate (T1), split application (1/2 basal dressing and 1/2 top-dressing at blossoming and boll forming stage)of potassium sulfate (T2), basal application of controlled-released compound fertilizers (T3) were designed. The same amount of potassium was applied with 150 kg K₂O ha^{–1 in each fertilizer treatment. The results indicated that application of potassium significantly increased chlorophyll and soluble protein contents, superoxide dismutase (SOD) and catalase (CAT) activities (at the leaf ages of 30, 40, and 60 days), seed cotton yield and lint yield, as compared with CK. Moreover, application of potassium produced significantly lower} malondialdehyde (MDA) content and peoxidase (POD) activity (at the leaf ages of 30 and 45 days), as compared with CK. Split application (1/2 basal dressing and 1/2 top-dressing at blossoming and boll forming stage)of potassium sulfate significantly increased soluble protein content (at the leaf ages of 30, 40, and 60 days), SOD (at the leaf ages of 15, 30, and 45 days)and CAT(at the leaf ages of 15 and 30 days) activities, seed cotton yield, lint yield and potassium use efficiency, and produced significantly lower MDA content (at the leaf ages of 30, 45, and 60 days) and POD activity (at the leaf age of 30 days), as compared with basal application of potassium sulfate and controlled-released compound fertilizers, respectively. As far as high yield and high efficiency concerned in the experiment, the most appropriate potassium fertilization for recommendation is treatment T2 with split application (1/2 basal dressing and 1/2 top-dressing at blossoming and boll forming stage)of potassium sulfate.

Identification and Evaluation of Drought Resistance in Different Peanut Varieties Widely Grown in Northern China

ZHANG Zhi-Meng,DAI Liang-Xiang,DING Hong,CHEN Dian-Xu,YANG Wei-Qiang,SONG Wen-Wu,WAN Shu-Bo

Acta Agron Sin. 2012, 38(03):  495-504.  doi:10.3724/SP.J.1006.2012.00471

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It is necessary to systematically identify and evaluate drought-resistant varieties for stable development of peanut production in arid and semi-arid regions in China. To establish drought resistance index of peanut cultivars, we determined 13 morphological and biochemical indices including plant height, number of branch, biomass, leaf water content and photosynthetic pigment content in the pot experiment at pod setting and pod filling stages with 29 peanut cultivars (strains) widely grown in north China under artificial water stress condition. Drought resistances of varieties were scored with drought coefficient method and subordinate function value under water stresses. The results showed that the same index of drought resistance characterized in different peanut varieties achieved different results, and 29 peanut varieties were divided into four grads: high tolerant, moderate tolerant, weaker tolerant, and drought susceptible. In the 29 cultivars (strains), we screened out the high drought tolerant varieties consisting of Tangke 8, Jihua 2, Jihua 4, Huayu 25, Huayu 17, Huayu 22, Datangyou, and Huayu 21. The cultivars (strains) of Huayu 20, Huayu 24, Weihua 6, Huayu 27, Luhua 11, Fuhua 11, Fuhua 13, Tangyou 4, Fenghua 1, and G2 had moderate drought resistance. The cultivars (strains) with weaker drought resistance were 16-8, Fuhua 10, M5, Huayu 16, and Luhua 14. At pod setting and pod filling stages Huayu 19, Huayu 23, Fenghua 6, Weihua 8, M7, and TE-2 were all drought susceptible. From seedling to pod setting stages under water stress, all morphological and biochemical indices but the number of branch and carotenoid content and their comprehensive D values could be taken as evaluation criteria. From seedling to pod filling stages under water stress, there only existed significanct correlation between leaf area and drought resistance. Either at pod setting or pod filling stages under water stress, comprehensive D value of the indices had significant correlation with drought resistance, which could be used to identify peanuts drought resistance.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Applications of Infrared Spectroscopy in the Analysis of Ordered Structure of Starch Grain

MAN Jian-Min, CAI Can-Hui, YAN Qiu-Xiang, HU Mao-Zhi, LIU Qiao-Quan, WEI Cun-Xu

Acta Agron Sin. 2012, 38(03):  505-513.  doi:10.3724/SP.J.1006.2012.00505

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Fourier transform infrared spectroscopy (FTIR) is used to study the ordered structure of starch grain, which has two modes: transmittance and attenuated total reflectance (ATR). In this paper, the different deconvolution parameters of spectra were applied to compare their effects on FTIR spectra in studying the ordered structure of starch grain. The results indicated that the different deconvolution parameters had significant effects on FTIR spectra and the intensities of relative peaks. The peak half-width of 19 cm^-1 and the resolution enhancement factor of 1.9 were ideal deconvolution parameters of spectra to obtain the better results. Native starches had A, B, and C three types of crystalline, their FTIR spectra showed some differences. Potato and Chinese yam starches had similar ATR-FTIR spectra, which were different from that of rice starch. However, rice and potato starches had similar transmittance-FTIR spectra, which were different from that of Chinese yam starch. The water content of sample affected the spectra of ATR-FTIR, but this effect was not detected when water content exceeded 60%. The ATR-FTIR spectra showed that the hydrolysis of amorphous structure in starch grain was faster than that of ordered structure during acid treatment. The ordered degree of structure in starch grain increased with increasing time of acid hydrolysis. The amyloglucosidase hydrolysis had no significant effect on the ordered degree of structure at the outside of starch grain by the ATR-FTIR spectra, but the ordered degree of structure of whole starch grain significantly increased with enzyme hydrolysis according to the transmittance-FTIR spectra. The amylose content is an important physicochemical property in determining the starch quality. Rice starches with different amylose contents showed the similar ATR-FTIR spectra. These results would be very useful for the application of FTIR to the analysis of ordered structure of starch grain.

Element Colocalization in Wheat Seed Revealed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)

WANG Yun-Xia, YANG Lian-Xin, Walter J. Horst

Acta Agron Sin. 2012, 38(03):  514-521.  doi:10.3724/SP.J.1006.2012.00514

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For enhancement of micronutrient concentrations in edible parts of food crops, element uptake and partition in plants, especially in seeds, should be better understanded. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a recently developed technology for examining mineral elements distribution in plant tissues. By using this technique, we quantitatively measured distributions of manganese (Mn), copper (Cu), zinc (Zn), and phosphorus (P) in different parts of wheat seeds. The concentrations of Cu, Zn, and P were the highest in aleurone layer and the lowest in endosperm with the difference of 15, 42, and 33 folds, respectively. The Mn concentration was the highest in embryo, which was 9-fold higher than the lowest concentration in endosperm. The concentration gradients of measured elements were also found in same parts of wheat grain. The concentrations of P, Mn, Cu, and Zn in endosperm close to aleurone layer were higher than those in the middle of wheat seed. Similarly, the element concentrations in scutellum were higher than those in embryo axis. The four elements had similar distribution pattern in wheat seed with a clear synchronization. This phenomenon suggested the colocalization of these elements in wheat seeds. Therefore, the translocations and accumulations of P, Mn, Cu, and Zn in wheat seeds might be closely related to each other, and the finding is useful for wheat biofortification programs in the future.

Optimum Harvest Time of Vicia cracca under Stress Condition

WANG Ying, HOU Yu, LI Xiao-Yu, SUN Hai-Xia, LIN Ji-Xiang, MU Chun-Sheng

Acta Agron Sin. 2012, 38(03):  522-527.  doi:10.3724/SP.J.1006.2012.00522

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Timely harvest is critical to achieve maximum seed viability, vigour and yield. Many native grasses display seed shattering and other seed production problems. Shattering during harvest is a major problem in seed production of Vicia. cracca (L.). The objective of this study was to further determine the optimum harvest time of V. cracca by simultaneously analyzing pod and seed morphological and physiological characters, as well as seed stress tolerance. Pods were harvested at three-day intervals from peak anthesis until pod shattering in pod development. The results showed that pod dry weight (DWT) and thousand seed weight (TSW) reached the maximum, as well as pod moisture content (PMC) reached the minimum from 36 to 42 days after peak anthesis (DAPA). The maximum percentage germination, germination rate and radicle length were at about 36 DAPA under NaCl and Na₂CO₃ stresses.Therefore, V. cracca can be harvested at six days before pod shattering without affecting yields and seed quality.

Effects of Growth Duration on Grain Yield and Quality in Rice (Oriza sativa L.)

LANG You-Zhong, DOU Yong-Xiu, WANG Mei-E, ZHANG Zu-Jian, ZHU Qing-Sen

Acta Agron Sin. 2012, 38(03):  528-534.  doi:10.3724/SP.J.1006.2012.00528

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It is important to clear the relationships of growth duration with rice yield and quality in determining the breeding objectives and cultivation strategies. In this paper, plants of japonica rice varieties Ning 111 and Chunjiang 302 with different growth durations resulted from short-day treatment were used to investigate the changes of yield and rice quality. The results showed that, the growth duration of more than 152 d had little effect on yield, but when less than 152 d, there was a significant positive correlation between growth duration and yield or dry matter accumulation; the smallest length and width of rice, as well as lowest protein content and setback of amylum were observed in the treatment G2 or G3, which had moderate growth duration of 131–132 d, the growth duration more than or less than 131–132 d would both increase the values of these rice quality indices; amylose content also showed a similar trend, and the minimum value in two species all appeared in treatment G3 (132 or 137d), while for breakdown of amylum, the trend was just opposite. The percentage of chalky grains, chalkiness and gelatinization temperature in two varieties rose with shortening growth duration; the effects of growth duration on milling quality were generally lower.

Variety Identification and Seed Test  by Peanut Pod Image Characteristics

HAN Zhong-Zhi, ZHAO You-Gang

Acta Agron Sin. 2012, 38(03):  535-540.  doi:10.3724/SP.J.1006.2012.00535

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To verify the feasibility of peanut variety recognition and seed testing by pod image characteristics, we screened 20 peanut varieties mainly released in North peanut regions and collected 50 traits based on pod morphology, colour and texture. We used PCA data optimization, neural networks, support vector machine, and clustering analysis to discuss the vvarieties iidentification, origin recognition, DUS characters selecting method and vvarietiesclustering process. It has been discovered that the PCA optimization SVM model is better and its identification effect is stable. By this model, the variety recognition rate was above 90% for 20 vvarieties, and the correct origin recognition rate of three origins reached 100%. Additionally, we sorted out some useful traits for seeds DUS test from the 50 features and established the dendrogram of 20 peanut varieties. The results of this study provided some references valuable to the selection of DUS traits, peanuts varieties, origin recognition, and peanut pedigree research.

RESEARCH NOTES

Cytological Observation of Anther Development of Photoperiod/Thermo- sensitive Male Sterile Line Huiyou50S in Brassica napus

GE Juan, GUO Yang-Fen, YU Cheng-Yu, ZHANG Guo-Yun, DONG Jun-Gang, DONG Zhen-Sheng

Acta Agron Sin. 2012, 38(03):  541-548.  doi:10.3724/SP.J.1006.2012.00541

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A photoperiod/thermo-sensitive male sterile line, named Huiyou50S, was developed from a spontaneous semi-sterile plant found in Brassica napus cultivar Huiyou50. The male sterility of Huiyou50S was controlled by recessive nuclear genes. Huiyou50S presents male sterile under high temperature and long photoperiod condition, and fertility under low temperature and short photoperiod. The cytological characters of pollen and the anther development of Huiyou50S at the different stages were compared with its near isogenic line Huiyou50F, which is the male fertile sibling, by techniques including semi-thin sections, scan electronic microscopy, pollen grains staining with aceto-carmine, and whole anther clearing with methyl salicylate. The result indicated that the anther development of Huiyou50S was similar to that of Huiyou50F from sporogenous cell, pollen mother cell, meiosis, to tetrad stage. At the uni-nucleate stage, although the exine formed, the protoplast of microspores condensed, and the cell became empty. At last all cellular content of pollen degraded completely and only the empty and distorted shell remained. The tapetum development of Huiyou50S was similar to that of Huiyou50F up to tetrad stage, but its tapetal cells rapidly disintegrated at the uni-nucleate stage, which occurred earlier than that in Huiyou50F, while the tapetum of Huiyou50F did not degenerate at this stage. In conclusion, the microspores of Huiyou50S abort mainly at the uni-nucleate stage, and there are some associations between pollen abortion and tapetal cells’ disintegration. This result is helpful to classification and utility of photoperiod/thermo-sensitive genic male sterility

Molecular Cloning and Express Analysis of Δ¹-Pyrroline-5-Carboxylate Synthetase (P5CS) Gene in Ramie

ZHOU Jing-Hua, XING Hu-Cheng,JIE Yu-Cheng, ZHONG Yin-Li, ZHU Shou-Jing, JIANG Jie, WANG Liang

Acta Agron Sin. 2012, 38(03):  549-555.  doi:10.3724/SP.J.1006.2012.00549

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Proline is one of osmotic regulators in plant, which plays an important role in regulating ramie in response to drought stress. The synthesis of proline has been reported to be restricted by the enzyme of Δ¹-pyrroline-5-carboxylate synthetase (P5CS). In this study, taking Xiangzhu 3 with drought tolerance as an experimental material, we obtained a ramie unigene highly identified with P5CS gene from the ramie transcription group sequencing, and the gene length was 1 448 bp. According to the known fragment, the 5' and 3' RACE PCR nest primers were designed, and a 590 bp 5′ terminal sequence and a 293 bp 3′ terminal sequence were amplified by RACE and RT-PCR, separately. The results of bioinformatics analysis showed that the full length of the P5CS gene was 2 318 bp, the open reading frame was 2 154 bp, coding 717 amino acids, the isoelectric point and the molecular weight of coded protein were 6.57 and 77.56 kD, respectively. Nucleotide sequence Blast indicated that the unigene of ramie shared an identity of 81%, 81%, 75% and 72% with P5CS genes of cotton, leprosy tree,Arabidopsis thaliana and rice, respectively, and the similarity in protein Blast was 86%, 85%, 78%, and 77%, respectively. The result showed it was a homologous gene of P5CS in ramie, and named BnP5CS1. Semi-quantitative RT-PCR analysis indicated that the expression of BnP5CS1 had a higher level in stem tip than in root, and the gene induced by the drought stress.P5CS is a key enzyme gene in the synthesis of proline in plants, so the cloning of BnP5CS1 gene might lay a foundation for the adversity resistance molecular breeding of ramie and further function analysis.

Determining Fumonisins in Corn by High Performance Liquid Chromatography with Immunoaffinity Column Cleanup

LI Wei-Xi, ZHENG Chuang-Mu, WU Li, LI Xin, LI Jing-Mei, SONG Jing-Ke, YANG Xiu-Lan, WANG Bu-Jun

Acta Agron Sin. 2012, 38(03):  556-562.  doi:10.3724/SP.J.1006.2012.00556

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Fumonisins are mycotoxins produced mainly by Fusarium verticillioides. Corn is frequently found being contaminated by fumonisins during its growth and storage. Epidemic study demonstrated that corn and corn-based products contaminated by fumonisins can cause equine leukoencephalomalacia and swine pulmonary oedema, also induce oesophageal cancer and neural tube defects of mankind. In this paper, a high performance liquid chromatography (HPLC) method with immunoaffinity columncleanup was established to determine the fumonisins B₁ (FB₁) and B₂ (FB₂) in corn. Meanwhile, the accuracy and reproducibility of the method were evaluated by statistical technique. The results showed that the linear ranges of FB₁ andFB₂ were 0.06–5.00 μg mL^-1 and 0.04–2.50 μg mL^-1, the recovery ranges were 76.6–93.8% and 77.9–93.4%, respectively. Thequantification limit of FB₁ andFB₂ was 0.09 mg kg^-1 and 0.06 mg kg^-1, respectively. The coefficient of variation within-laboratory repeatability was below 5%, and that between-laboratories reproducibility was below 6%. Research results indicated that this method possessed good linearity, accuracy, precision, sensitivity, repeatability within a laboratory and among laboratories. Therefore, this method was proved to be suitable for determination of fumonisins in corn. Applying this method, fumonisins in 310 specimens of corn were determined. Results showed that total fumonisins (B₁+ B₂) ranged from 0.20 to 9.06 mg kg^-1 for field corn, and from 0.21 to 6.10 mg kg^-1 for stored corn. It is proposed that monitoring fumonisins’ level in corn should be reinforced to protect the health of man and livestock.

Effect of Structural Differentiation of Fruit Dehiscence Zone on Pod Dehiscence in Oilseed Rape

WANG Ting, JI Shu-Yi, WU Hong

Acta Agron Sin. 2012, 38(03):  563-569.  doi:10.3724/SP.J.1006.2012.00563

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Oilseed rape plants disperse their seeds by pod-shattering known as Pod dehiscence, which causes yield loss. To investigate the effect of structure differentiation on pod shattering, we studied the developmental process and structural characteristics of fruit “dehiscence zone” of two varieties with different pod shattering behavior Zhongshuang 9 and Zhongshuang 11, by semi-thin section fluorescence microscopy with. Our observations revealed that: (1) rape pod gradually differentiated to form “dehiscence zone” in fruit development, which was composed of dehiscence zone (or separation layer), lignified valve edge, lignified endocarp b and replum cells; (2) The dehiscence zone of Zhongshuang 9 was found at 15DAF (day after flowering), and meanwhile the walls of valve edge cells, endocarp b cells and replum cells were thickened, and that of Zhongshuang 11 did not show these features until 25DAF. The dehiscence zone was fully formed in Zhongshuang 9 at 25DAF, while in Zhongshuang 11 at 30DAF.The separation of dehiscence zone cells was observed at 30DAF in Zhongshuang 9, while this occurred in 35DAF for Zhongshuang 11. In addition, more cell separation sites occurring between lignified replum cells enhanced pod shattering in Zhongshuang 9. These results provide a theoretical guidance for molecular regulation of pod shattering and oilseed rape breeding for pod shattering-resistance.