Table of Content

12 September 2012, Volume 38 Issue 09

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REVIEW

Research on Resistance Mechanism of Cotton to Verticillium Wilt

XU Li,ZHU Long-Fu,ZHANG Xian-Long

Acta Agron Sin. 2012, 38(09):  1553-1560.  doi:10.3724/SP.J.1006.2012.01553

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Verticillium wilt in cotton caused by Verticillium dahliae is a soil-borne vascular disease, which results in serious loss in yield and fiber quality yearly. However, traditional strategy doesn’t work very well to control the disease but the local control, and it isn’t an efficient way to develop a new cotton variety with resistances to Verticillium wilt via the conventional method, and there are few successful reports with conventional breeding method for disease resistance improvement due to shortage of high resistance germplasm, so the control of this disease has been an obstacle in cotton production. Recently, more researches focus on the resistance mechanism of cotton to this disease. Coupled with results in other crops lately, here, we summarized the processes in cotton for controlling Verticilliumwilt based on signal transduction of R gene, the putative role of ethylene in the interaction between cotton and V. dahliae, physiological and biochemical resistance as well as host structural resistance, and from which some suggestions may be inferred for molecular breeding in disease resistance.

 

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Expression Pattern of Arabidopsis RBCS-1A Gene in Response to Light Treatments and Application Evaluation of Its Promoter in Transgenic Engineering

XI Yu-Lin,ZHOU Peng,SONG Mei-Fang,LI Zhi-Yong,MENG Fan-Hua,YANG Jian-Ping

Acta Agron Sin. 2012, 38(09):  1561-1569.  doi:10.3724/SP.J.1006.2012.01561

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RBCS gene encodes the small subunit of Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), which catalyzes the rate-limiting step of CO2 fixation in photosynthesis. It is very important for crop improvement to study the gene expression pattern and promoter activity of RBCS in response to light. In this study, we analyzed the gene expression pattern of Arabidopsis RBCS-1A in response to light by Real-time quantitative PCR. The results indicated that the expression of AtRBCS-1A was induced by light, and had the tissue-specific feature. In silico analysis revealed that many cis-acting elements for light regulation were found in the promoter of AtRBCS-1A. Based on this information, we isolated a genomic sequence with 1 691 bp upstream of the translation start codon of AtRBCS-1A using PCR, constructed plasmid vector with AtRBCS-1A promoter fused with GUS (encoding β-glucuronidase) reporter gene, and then generated transgenic Arabidopsis by floral dip. Histochemical analysis of the transgenic lines suggested that AtRBCS-1A promoter was a light-induced and tissue-specific promoter. All the analyses preliminarily prove that AtRBCS-1A promoter has important application value and can be used in plant transgenic engineering.

Genome-Wide Identification, Classification, and Expression of NF-YB Gene Family in Soybean

ZHENG Wei-Jun,XU Zhao-Shi,FENG Zhi-Juan,LI Lian-Cheng,CHEN Ming,CHAI Shou-Cheng,MA You-Zhi

Acta Agron Sin. 2012, 38(09):  1570-1582.  doi:10.3724/SP.J.1006.2012.01570

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Based on soybean genome database and bioinformatics method, we obtained soybean NF-YB family genes and their positions on chromosome and duplication information. NF-YB proteins were classified according to their phylogenetic relationship. The soybean RNA-sequencing data from the SoyBase database and EST data from NCBI UniGene were used to analyze the expression pattern of these genes at different development stages. A total of 28 NF-YB genes were systematically identified from soybean and classified into three types. They were located on 14 chromosomes and most of them had stress related cis-acting elements in their promoter regions. Ten differentially expressed genes were found at each developmental stage, and four of them were highly expressed in different tissues other than root nodules and root. Among other six genes, two were highly expressed in root nodule, two were specifically expressed in root nodules and two were specifically expressed in root. The results facilitate functional analysis and utilization of NF-YB genes in crop genetic improvement.

Identifications of DNA Sequences Encoding Key Region of SCR Interacting with SRK Extracellular Domain by Using Yeast Two-Hybrid System

XUE Li-Yan,LUO Bing,ZHU Li-Quan,YANG Yong-Jun,ZHANG He-Cui,CHANG Deng-Long,CHEN Song,PENG Yi-Bo,YANG Hong,ZENG Jing,YANG Kun,GAO Qi-Guo,LI Cheng-Qiong,REN Xue-Song,WANG Xiao-Jia

Acta Agron Sin. 2012, 38(09):  1583-1591.  doi:10.3724/SP.J.1006.2012.01583

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The S-locus cystein-rich protein (SCR) is the male-determining factor of self-incompatibility in Brassica. In this study, the SCR fragments with different lengths amplified from Brassica oleracea L. were ligated with pGBKT7 to construct recombinant bait plasmids, which were then transformed into yeast Y2HGold cells for detecting their interaction with the S-locus receptor kinase extracellular domain (eSRK) in Brassica oleracea by using the yeast two-hybrid system. The results showed that recombinant vectors were not activated autonomously. The full length SCR could interact with eSRK, and the core region in the SCR was located between 97 and 186 bp. Moreover, the result also indicated that the splicing site of signal peptides of this haplotype SCR and its several adjacent amino acid residues could affect the interaction. These conclusions add some novel insights into the mechanism research of self- incompatibility in Brassica.

Proteomic Analysis of Leaves of the Chlorophyll-Deficient Wheat Mutant Mt6172 and Its Wild-Type through 2D-Difference Gel Electrophoresis

SONG Su-Jie,GU Jia-Yu,GUO Hui-Jun,ZHAO Lin-Shu,ZHAO Shi-Rong,LI Jun-Hui, ZHAO Bao-Cun,LIU Lu-Xiang

Acta Agron Sin. 2012, 38(09):  1592-1606.  doi:10.3724/SP.J.1006.2012.01592

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Two-dimensional difference gel electrophoresis (2D-DIGE) proteomic approach was used to identify differentially expressed proteins in the leaves of chlorophyll-deficient wheat mutant Mt6172 derived from space environment mutagenesis. A total of 1 654 protein spots were detected, of which 100 spots showed 1.5-fold or higher volume ratio in the leaves of Mt6172 or its wide-type Han 6172. Eighty-five spots subject to mass spectrometry and 62 spots representing 29 distinct proteins were identified and classified into 10 functional groups. Among these differential proteins, 50 were down-regulated and 12 were up-regulated. Most of the down-regulated proteins were located in the subcellular system of chloroplast, including the subunits of PSI, PSII, NAD(P)H dehydrogenase complex and ATP synthase, and the proteins involved in Calvin-Benson cycle, glucose metabolic process and stress responses. Compared to the proteins in chloroplast, the identified non-chloroplast proteins were mainly up-regulated, including the proteins involved in response to oxidative stress, transcriptional activation, and protein folding process. The results suggested that the early death of the albino phenotype of Mt6172 might result from the deficiency of main photosynthesis protein complexes, the decrease of chloroplast antioxidant capacity, and the obstacle of post-transcriptional modification process for chloroplast RNAs.

Cloning and Functional Analysis of GmNF-YC2 Gene in Soybean (Glycine max)

CAO Yan,ZHANG Xiao-Mei,CHEN Xin-Jian,FU Yong-Fu

Acta Agron Sin. 2012, 38(09):  1607-1616.  doi:10.3724/SP.J.1006.2012.01607

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The eukaryotic nuclear factor Y (NF-Y) is a ubiquitous transcription factor complex composed of three distinct subunits (NF-YA, NF-YB, and NF-YC).NF-Y transcription factors typically act on the promoters of other regulatory factors to modulate gene expressions. Here, a NF-YC homologue, GmNF-YC2, was cloned from soybean variety KN18. The expression profiles checked by quantitative Real-time RT-PCR (qRT-PCR) showed that GmNF-YC2 was regulated by light but not by circadian clock. And GmNF-YC2 was expressed at the highest level in third trifoliolates at flowering. The results suggested that GmNF-YC2 was one of the important genes in the regulation of flowering in soybean. The transient expression in Arabidopsis protoplasts displayed that GmNF-YC2 protein was localized in nuclear section. It paved a way to study the function of NF-Y family in soybean and its application in soybean molecular breeding.

Enhancement of Resistance to Fusarium Head Blight and Sharp Eyespot in Gastrodianin Transgenic Wheat

ZHOU Miao-Ping,YANG Xue-Ming,YAO Jin-Bao,REN Li-Juan,ZHANG Zeng-Yan,MA Hong-Xiang

Acta Agron Sin. 2012, 38(09):  1617-1624.  doi:10.3724/SP.J.1006.2012.01617

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Gastrodianin, also called Gastrodia antifungal protein (GAFP), can inhibit the growth of many fungal pathogens in vitro. The Gastrodianin gene driven by maize ubiquitin promoter in the transformation vector pAC-GAFP was introduced into wheat cultivars Yangmai 158 and Alondra via particle bombardment to investigate the resistance to fungal pathogens in transgenic wheat. A total of 14 transgenic lines were obtained and verified through PCR, FISH, and semiquantitative RT-PCR analyses. The results showed that the alien Gastrodianin gene was integrated into wheat genome in the transgenic lines and heritable to the offspring. The alien Gastrodianin gene was expressed at different levels in the transgenic lines of the homozygous T₅ generation. The assessment of resistance to Fusarium graminearum and Rhizoctonia cerealis indicated that Gastrodianin suppressed the growth of pathogens in transgenic plants and reduced the severity of both diseases. The enhanced resistance degree was associated with the expression level of Gastrodianin gene in transgenic plants.

Expression of Rice Defence Genes under Small Brown Planthopper Stress

LI Wan-Chang,YU Jiao-Jiao,DUAN Can-Xing,ZHU Zhen-Dong,WANG Xiao-Ming

Acta Agron Sin. 2012, 38(09):  1625-1630.  doi:10.3724/SP.J.1006.2012.01625

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The small brown planthopper (SBPH), Laodelphax striatellus Fallén (Homoptera: Delphacide), is an economically important pest in rice (Oryza sativaL.) production in China.Real-time PCR was used to determine transcriptional level of rice defence genes after SBPH infestation using specific primers. The expression level of SA synthesis-related genes PAL, NPR1, EDS1, and PAD4 was higher in resistant Mudgo than in susceptible Kittake after SBPHfeeding. The expression level of gene PAL in 12 h-infestation rice was 6.914 times of that in untreated rice. The gene PAL accumulation was more rapid and at higher levels in Mudgo and the expression amount in Mudgo was 42.848, 70.743, and 69.193 times of that in Kittake at 24, 48, and 72 h after SBPH infestation, respectively.The gene NPR1 expression in Mudgo was 4.690, 6.231, and 4.112 times of that in Kittake after SBPH infestation for 12, 36, and 72 h. There was significant difference in transcriptional level of the JA synthesis-related genes LOX and AOS2 after 36 h-infestation between Mudgo and Kittake. The expression level was substantially lower in Mudgo than in Kittake at subsequent time points. In addition, the expression level of receptor gene EIN2 in ethylene signaling pathway was higher in Kittake than in Mudgo after SBPHfeeding. The above results indicated that SBPH feeding activatedthe salicylic acid signaling pathway in resistantMudgo and induced the defenses in susceptible Kittake associated with a JA/ethylene-dependent pathway. The genesPAL and NPR1 played a considerable role in the regulation of Mudgo expressing resistanceto SBPH.

Construction of eSRK Chimeras and Interaction between eSRK Chimeras and SCRs from Brassica oleracea L.

WEI Jing-Yi,GAO Qi-Guo,REN Xue-Song,WANG Xiao-Jia,LI Cheng-Qiong,SONG Ming

Acta Agron Sin. 2012, 38(09):  1631-1639.  doi:10.3724/SP.J.1006.2012.01631

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Self-incompatibility in Brassica is mediated by allele-specific interactions between stigma-expressed S-locus receptor kinase (SRK) and pollen coat-localized S-locus cysteinerich (SCR) ligands encoded by the S-locus haplotype. To identify amino acid fragments within the SRK extracellular domain (eSRK) that are required for ligand-selective activation, we constructed chimeric eSRK between two S-locus haplotypes in Brassica oleracea, and identified the interaction between eSRK chimeras and SCRs by yeast two-hybrid system. The results showed that SRK_E (not chimera) could interact with SCR_E, and SRK_F could interact with SCR_F. All of eSRK chimeras could not interact with SCRs. The hypervariable regions, HVI and HVII, were essential for specificity in the SRK-SCR interaction. However, eSRK chimeras could not interact with SCR_F, although they contained hypervariable regions come from eSRK_F, which should be related with the overall sequence or 3D conformation of the segments determining SI specificity.

Development and Analysis of Introgression Lines on Chromosomes 1H–7H in Barley

LAI Yong,FENG Jing-Xia,SI Er-Jing,LI Bao-Chun,MENG Ya-Xiong,MA Xiao-Le,YANG Ke,SHANG Xu-Wu,WANG Hua-Jun

Acta Agron Sin. 2012, 38(09):  1640-1648.  doi:10.3724/SP.J.1006.2012.01640

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To provide a suitable population for quantitative trait locus (QTL) mapping and genetic research of favorable genes in barley (Hordeum valgare L.), we constructed a set of introgression lines (ILs, BC₃F₂) with the genetic background of recurrent parent Scarlett using 96 SSR markers that cover the whole genome of wild barley ISR42-8. This IL population contained 66 lines, and the target segments were determined with the 96 SSR markers distributed on chromosomes 1H to 7H of barley. The average length of target segments was 27.6 cM. The line IL-52 carried the longest introgressed segment (100.5 cM), and the line IL-50 carried the shortest introgressed segment (1.5 cM). There were 33 lines containing a single segment. The clustering analysis showed that the genetic backgrounds of these introgression lines were rather similar with each other. The genetic similarity coefficients ranged from 0.708 to 1.000, with the mean of 0.917. A QTL for tiller number was mapped in the interval of 87.5–110.0 cM on chromosome 4H, the size of which was 22.5 cM, and the polymorphism marker was MGB396.

Molecular Cloning and Expression Analysis of GhSAMDC at Low Temperature Stress in Cotton (Gossypium hirsutum L.)

GENG Wei-Dong,LI Yan-Jun,ZHANG Xin-Yu,ZHU Hua-Guo,SUN Jie

Acta Agron Sin. 2012, 38(09):  1649-1656.  doi:10.3724/SP.J.1006.2012.01649

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S-adenosylmethionine decarboxylase is one of the key enzymes in polyamine biosynthesis. With the increase of polyamine accumulation in plants, SAMDC can improve crop tolerance to environment stresses. We cloned the S-adenosylmethionine decarboxylase gene from Gossypium hirsutum by RACE and RT-PCR, named GhSAMDC (GenBank accession number: JN020148). The cDNA full length was 1 874 bp, with three open reading frames, i.e. tiny ORF (tORF), upstream ORF (uORF) and main ORF (mORF). The mORF was 1 064 bp encoding 355 amino acids with a molecular mass of 38.25 kD, and its deduced protein had two highly conserved function domains (proenzyme cleavage site and PEST domain). The complete genomic DNA sequence of GhSAMDC was 2 743 bp in length with three introns, all of which were located in 5' UTR, and one lay in theuORF. Phylogenetic analysis showed GhSAMDC was the closest to that in Vitis vinifera, and Real-time PCR suggested that GhSAMDC was induced by cold stress. It showed lower gene expression level in cold resistant cultivar Xinluzao 33 than in cold sensitive cultivar Xinluzao 1.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Nitrogen Application Rate on Water Consumption Characteristics and Grain Yield in Rainfed Wheat

DUAN Wen-Xue,YU Zhen-Wen,ZHANG Yong-Li,WANG Dong,SHI Yu

Acta Agron Sin. 2012, 38(09):  1657-1664.  doi:10.3724/SP.J.1006.2012.01657

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Nitrogen management plays a key role in high yield of rainfed wheat. To propose a suitable nitrogen application rate for the rainfed wheat in Yellow and Huaihe River Valleys, particularly in Shandong Province, we explored the water consumption characteristics and final yield of dryland wheat in response to different nitrogen application rates in the 2009–2010 and 2010–2011 growing seasons. Wheat cultivars Jimai 22 (in 2009–2010 growing season) and Shannong 16 (in 2010–2011 growing season) were both supplied with nitrogen fertilizer at 0 (N0), 90 (N1),120 (N2), 150 (N3), 180 (N4), and 210 kg ha^-1 (N5). In N3 treatment, the water consumption amount had no significant difference with that in N1 or N2 treatment from sowing to jointing stage, but significantly higher from jointing to maturity stage. The water consumption amounts in N4 treatment had no significant changes at various stages, and increased significantly in N5 treatment from revival to anthesis stage. When the nitrogen application rate was raised from 90 to 150 kg ha^-1, wheat showed an increased capability to absorb soil water from deep soil layers. However, further increase of nitrogen fertilizer had no effect on consumption amount of soil water below 80 cm from the surface. The soil evaporation after jointing was significantly lower in N3 treatment than in N1 and N2 treatments, and the water use efficiency of flag leaf after anthesis was significantly higher in N3 treatment than in N1 and N2 treatments. Compared to N3 treatment, N4 and N5 treatments had no significant effects on soil evaporation after jointing and water use efficiency of flag leaf after anthesis. Therefore, 150 kg ha^-1 is proposed as the optimal nitrogen application rate for rainfed wheat grown in the environment similar to that in this experiment, because N3 treatment resulted in the highest grain yieldand water use efficiency, as well as relatively high nitrogen productive efficiency.

Optimal Moisture Content and Physiological Bases of Rice Seeds Storage at Room Temperature

HU Qun-Wen,XIN Xia,CHEN Xiao-Ling,LIU Xu,LU Xin-Xiong

Acta Agron Sin. 2012, 38(09):  1665-1671.  doi:10.3724/SP.J.1006.2012.01665

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The objective of this study was to investigate the optimal moisture content for rice seeds storage and the physiological bases by measuring the seed viability, vigor index, malondialdehyde (MDA) content, leakage electrical conductivity, and antioxidant enzyme activities in the embryo of rice seeds, which had been stored at room temperature in Nanchang for nine years with moisture content (MC) at 10.6%, 7.0%, 6.0%, 5.0%, 4.0%, and 3.0% respectively. The data showed that after nine years storage at room temperature, the germination rates of seeds with MC of 5.0–6.0% were still higher than 50%, while that with other MCs much lower. Therefore the MC of 5.0–6.0% was regarded as the optimal moisture content (MCopt) for rice seed storage at room temperature. The activities of APX and CAT in the 12 h-imbied embryo of nine-year stored seeds with MCopt were much higher than those with other MCs, which showed no or minimal differences with those stored at -18℃. There were no significant changes in the activities of GR or SOD. These results suggested that the MCopt could maintain higher activities of APX and CAT, which might be one of the important reasons for retarding the reduction of seed viability during storage. No clear relationship was detected between seed leakage electrical conductivity or MDA content in embryo and seed viability or moisture content. When the seeds were dried to MC of 3.0%, the over-drying injury was introduced as the markedly decline in germination rate and germination index.

Physiological Characteristics of Delaying Leaf Senescence in Maize Inbred Lines Tolerant to Potassium Deficiency

WANG Xiao-Lei,YU Hai-Qiu,LIU Ning,YI Bing,CAO Min-Jian

Acta Agron Sin. 2012, 38(09):  1672-1679.  doi:10.3724/SP.J.1006.2012.01672

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A field experiment was conducted using two maize inbred lines with significant difference in potassium sensitivity to investigate the effects of low potassium stress at grain filling stage on leaf stay-green, chlorophyll contents, photosynthetic gas exchange and chlorophyll fluorescence parameters, and various antioxidant enzymes activities related with senescence. The results showed that, under low potassium stress, the characteristics of leaf stay-green of 90-21-3 were better than that of D937. In addition to changes in stay-green, it was found that decreased more strongly in D937, the photosynthetic pigment level in 90-21-3 was remained nearly normal under K deficiency conditions. Moreover, compared with D937, 90-21-3 showed a lower stomatal restriction and a higher electronic transition capacity after accelerated ageing by K deficiency. F_PSII, F_v, F_m in 90-21-3 were higher than in D937, while F_o was lower than those in D937. In addition, under low potassium stress, activities of PEPC and NADK were less decreased and photo system was less damaged in 90-21-3. And the content of malondialdehyde (MDA) was lower in 90-21-3 than in D937 under low potassium stress. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in ear leaf of 90-21-3 were obviously higher than those of D937 under low potassium stress, indicating that the antioxidant enzymes could eliminate reactive oxygen species, inhibit the membrane lipid peroxidation and decrease the content of MDA more efficiently in 90-21-3. Therefore, compared with D937, the leaf senescence of 90-21-3 was relatively slower, which could prolong the functional period of leaves. The activity of NADK could provide NADP as electronic receptors for photoreaction, at the same time the increased activity of PEPC led to more effective fixation of CO₂, and the synergistic effect of light and dark reactions contributed to the higher photosynthetic rate and yield in 90-21-3.

Screening of Drought Tolerant Agronomic Trait Indices of Colored Cotton Varieties (Lines) in Gansu Province

CHEN Yu-Liang,SHI You-Tai,LUO Jun-Jie,WANG Di,HOU Yi-Qing,LI Zhong-Wang,ZHANG Bing-Xian

Acta Agron Sin. 2012, 38(09):  1680-1687.  doi:10.3724/SP.J.1006.2012.01680

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Available drought-tolerant indicators that help to screen drought-tolerant parents are significant for breeders to develop new varieties in the water deficient regions. In the paper, the water deficient trials were performed with randomized block design with three treatments. The agronomic traits and drought-tolerant indicators of eight colored cotton varieties (lines) were investigated in 2010–2011. The results showed that the seed cotton yield reduced, and plant height, leaf number at flowering-bolling stage, boll number per plant, number of fruiting branch, number of fruit nodes, single boll weight, harvest index, stem diameter, seed index, and fiber length also decreased under drought stresses. There were significantly positive correlation among drought resistance index, plant height, number of fruit nodes, boll number per plant, leaf number at flowering-bolling stage, single boll weight, harvest index, stem diameter, and number of fruiting branch. The principal component and the multiple stepwise regression analyses showed that the boll number per plant, single boll weight, and the leaf number at flowering-bolling stage could be regarded as the simple and intuitive identification indexes of drought resistance in colored cotton, and number of fruiting branch, fiber length, plant height, number of fruit nodes, boll weight, and seed index could be used as indicators for determining or influencing colored cotton drought resistance.

Effect of Fixation and Staining Methods on Structure Observation of Endosperm Cell of Wheat

WANG Ling-Ling,LIU Zhi,XIONG Fei,LI Dong-Liang,ZHOU Wei-Dong,CHEN Yi-Fang,WANG Zhong

Acta Agron Sin. 2012, 38(09):  1688-1697.  doi:10.3724/SP.J.1006.2012.01688

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Two fixing methods and five staining agents were used to compare which one is best for optimal observation of endosperm cell of wheat under optical and transmission electron microscopes. Caryopsis samples of Yangmai 16 were fixed with glutaraldehyde-osmium tetroxide (GA-OsO₄) or potassium permanganate and stained withtoluidine blue (TBO), polychromatic dye, periodic acid schiff (PAS), coomassie brilliant blue, or PAS-TBO during the preparation of semi-thin sections. The GA-OsO₄ fixation showed better overall performance than the potassium permanganate fixation, but the best observation was got by potassium permanganate fixationand PAS-TBO counterstaining. The GA-OsO₄ fixation had the advantage of preserving endosperm cell intrinsic feature in ultra-thin section but the disadvantage of unclear display of the membranous structure. The potassium permanganate fixation was able to show the structure of the cell endomembranevividly with satisfactory contrast between background and membranous structure; however, the color stained in polysaccharide and protein was poor. Therefore, appropriate fixation and staining methods should be based on the target and objective of experiment.

Effect of PASP-KT-NAA on Leaf Senescence and Grain Filling Rate during the Grain-Filling Period in Different Temperature Zones

XU Tian-Jun,DONG Zhi-Qiang,GAO Jiao,CHEN Chuan-Xiao,JIAO Liu,XIE Zhen-Xing

Acta Agron Sin. 2012, 38(09):  1698-1709.  doi:10.3724/SP.J.1006.2012.01698

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Field experiment was performed to investigate the effects of the chemical regulation of PASP-KT-NAA (PKN) on leaf senescence physiology and grain filling rate under different temperatures. The result showed that the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), chlorophyll concentration in ear leaves of two maize cultivars were declined, while malondialdehyde (MDA) content increased in three accumulate temperature zones with low temperature. In the same accumulated temperature zone, and in process of growth, SOD, POD, CAT activities showed the trend of a single peak curve with “first increase and then decrease”, and MDA content showed an opposite trend. PKN treatment increased SOD, POD, CAT activities and chlorophyll contents of ear leaves, while declined MDA content in ear leaves of Zhengdan 958 and Fengdan 3. From the first accumulated temperature zone to the third accumulated temperature zone, the grain weight of two maize cultivars show a S-shape increase in the “low-fast-low” type and the grain filling rate showed an “increased and then declined” trend. The grain weight and the grain filling rate of the first accumulated temperature zone were higher than those of the second and the third accumulated temperature zones. PKN treatment had higher grain weight and the grain filling rate compared with the control. In 2010 and 2011, the yield of two varieties of maize increased in the PKN treatment. The yield of Zhengdan 958 and Fengdan 3 in the third accumulated temperature zone was 2.58%, 1.17% and 2.04%, 1.48% higher than that in the first and second accumulated temperature zones, in 2010 and 8.2%, 5.1% and 3.4%, 0.8% higher than that in the first and second accumulated temperature zones in 2011. Thus, the chemical regulation in proved to have contributions to delaying the leaf senescence, improving the grain filling rate, and ultimately increasing the yield in maize.

Modulation of Exogenous Nitric Oxide on Photosystem II Functions in Wheat Seedlings under Drought Stress

SHAO Rui-Xin,XIN Long-Fei,YANG Qing-Hua,SHANG-GUAN Zhou-Ping

Acta Agron Sin. 2012, 38(09):  1710-1715.  doi:10.3724/SP.J.1006.2012.01710

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Nitric oxide (NO) has emerged as a key molecule involving in tolerating various abiotic stresses that induce physiological responses in plants. To characterize the role of NO in tolerance of photosystem II (PSII) to drought stress induced by polyethylene glycol (PEG), we used sodium nitroprusside (SNP) of 0.1 mmol L^-1as exogenous NO donor to study the biologically protective effects of NO at a low concentration on PSII functions in wheat (Triticum aestivum L.) seedlings hydroponically grown under -0.5 MPa PEG stress. Under drought stress, SNP supplement increased the water potential (Ψ_w) and chlorophyll content, maintained favorable status of electron transport (Ф_PSII and F_m/F_o) and potential high activity of PSII reaction centers (F_v/F_o) on the first and third days of treatment. The open proportion of PSII reaction centers (q_P) and absorbed-light allocation to photochemical reaction(Pr)were higher in the treatment of SNP supplement under drought stress than in only PEG treatment. SNP alleviated drought-induced inhibition to absorbed-energy conversion of open PSII (F_v′/F_m′), safely dissipating excessive light energy in PSII reaction centers. Therefore, NO could modulate the PSII functions in photosynthesis of wheatseedlings hydroponically exposed to PEG stress.

RESEARCH NOTES

Differential Proteomics on Multi-Ovary and Mono-Ovary Trait of Wheat

WANG Zhi-Jun,MA Shou-Cai,BI Xiao-Jing,SHI Xiu-Xiu,LI Qing-Feng,HAN Fang,QI Jia-Jia,WANG Shu-Ping,ZHANG Gai-Sheng,NIU Na

Acta Agron Sin. 2012, 38(09):  1716-1722.  doi:10.3724/SP.J.1006.2012.01716

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 Muliti-ovary is a favorable trait that might be a solution for increasing the yield of hybrid seed in wheat. In this study, the differential proteins of panicles at tetrad stage were detected between the mono-ovary line 77(2) and its near-isogenic multi-ovary line Mu77(2) using SDS-PAGE method. Approximately 450 protein spots were observed in the 2-DE gels within the area of pH 4–7 and molecular weight 14.4–97.4 kD, of which 30 were identified as differential protein spots with at least double expression levels and 99% statisticalty significant difference. Six specific protein spots with differential expressions were then analyzed using LC-MS/MS method. The result showed that they are glycine-rich RNA-binding protein (S1), SGT1-1 (S2), HMG-I/Y protein (S3), glutathione transferase (S4), fructose-bisphosphate aldolase (S5), and unnamed protein (S6). These proteins are involved in the regulation of DNA transcription, protein translation, energy metabolism, signal transduction, plants defense, and other resistance function, and might be related to the formation of multi-ovary in wheat.

Starch Granule Size Distribution in Grains of Maize with Different Endosperm Types

CUI Li-Na,ZHANG Hai-Yan,MENG Jia-Jia,SHI De-Yang,ZHANG Hong,DONG Shu-Ting

Acta Agron Sin. 2012, 38(09):  1723-1727.  doi:10.3724/SP.J.1006.2012.01723

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Maize (Zea mays L.) kernel dry weight contains about 70% starch. Many studies have focused on the effects of sowing date, variety and nitrogen top-dressing on starch granule distribution in single variety or two varieties. But starch granule size distribution in grains of different endosperm types of maize has not been clear yet. Four maize varieties including super-sweet corn (Huawei 6), popcorn (Tebao 2), waxy corn (Xixinghuangnuo 6) and dent corn (Zhengdan 958) were used to study the starch granule size distribution and the starch granule arrangement in grains by laser diffraction grain size analyzer, transmission electron and scanning electron microscopy. The results showed that distribution of starch granules volume in grains of the maizes were changed in a triple humped curve. The volume proportion of starch granules with diameter lower than 2 μm was the least, while that with diameterhigher than 15 μm was the more (that with diameter from 2 to 15 μm in super-sweet corn grain was the most). The average diameter showed following order: the waxy>the pop>the dent>the super sweet. Correlation analysis indicated that the grain weight and starch content were significantly correlated with the volume percentage of starch granules with diameter higher than 2 μm; while the contents of protein, amino acid, crude fat and test weight had no correlation with volume of starch granule with all size ranges. Transmission electron microscopy showed that the starch granules in grains ofdent and super sweet corn were rotund mostly, with a great deal of drapes. Starch granule arrangement of dent corn was sparse, with abundant lipid droplet, while that of super sweet corn was very sparse; with rich lipid droplet. The starch granule in grains of pop corn was square and oblong, and extruded one another, with thick and skimp drapes, with was highly compact with abundant lipid droplet. The starch granule in grains of way corn was rotund and elliptic, with low and skimp drapes, compact arrangement and abundant lipid droplets. Scanning electron microscopy showed that the starch granules in grains of dent, super sweet and waxy corn were spherical. A small quantity of depressed starch granules were demonstrated in dent corn, while none of depressed starch granules were detected in super sweet corn with reticulate configuration in surface of starch granules. Moreover the cell did not be filled with starch granules and filling agent. The starch granule was polyhedral in pop corn with a very few depressed starch granules.

Effect of Paclobutrazol under Different N-Application Rates on Photosynthesis and Starch Accumulation in Edible Sweetpotato

CHEN Xiao-Gang,LI Hong-Min,ZHANG Ai-Jun,SHI Xin-Min,TANG Zhong-Hou,WEI Meng,SHI Chun-Yu

Acta Agron Sin. 2012, 38(09):  1728-1733.  doi:10.3724/SP.J.1006.2012.01728

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A field experiment was conducted to study the effects on leaf photosynthesis, root tuber starch accumulation and yield in edible sweetpotato (Ipomoea batatas L. Lam cv. Beijing 553) with two nitrogen treatments (120 and 240 kg ha^–1) and three paclobutrazol (PP₃₃₃ ) spraying levels (0, 100, and 200 mg ha^–1). The result showed that increasing nitrogen application boosted P_n and chlorophyll content, reduced dry matter allocation in root tuber and starch accumulation rate, and significantly reduced the fresh weight per lump of root tuber(by 8.0%) and the starch yield and root tuber yield (by 30.7% and 20.5%). Spraying PP₃₃₃ improved P_n and chlorophyll content, accelerated the transportation of carbohydrate from leaf to root tuber and enhanced its allocation in root tuber, the starch accumulation rate, significantly the fresh weight per lump of root tuber (by 18.6%) and the yield of starch and fresh weight of root tuber(by 46.1% and 32.5%). It was indicated that both starch accumulation and yield could be regulated by PP₃₃₃ under high nitrogen application rate.

Effects of Low Temperature Stress during Flowering Stage on Flowering and Seed Setting of Rice in Panxi Region, Sichuan Province

ZHANG Rong-Ping,MA Jun,CAI Guang-Ze,SUN Yong-Jian

Acta Agron Sin. 2012, 38(09):  1734-1742.  doi:10.3724/SP.J.1006.2012.01734

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An experiment was conducted in growth chamber with low temperature treatments during flowering stage using three indica and three japonica rice varieties (combinations) to study the effects of low temperature stress onflowering and setting. The results showed that there were different responses and characteristics of flowering, anther, pollen, setting and their relationship between indica and japonica to low temperature stress during flowering stage. The conventional japonica rice had high cold tolerance to low temperature. In comparison with control, the reduction range of the anther volume, anther dehiscence rate, pollen fertility rate, pollen number on stigma and germination rate of pollen on stigma of indica rice varieties (combinations) under low temperature stress was larger than that of japonica rice varieties (combinations). Under low temperature stress during flowering stage, the reduction range of yield components of indica rice varieties (combinations) was greater than that of japonica rice varieties (combinations). The correlation analysis showed a close relation between the seed setting of rice and the main characters of anther and pollen. It is clear that low temperature stress affects the development and maturation of anther and pollen, further blocks anther dehiscence, resulting in insufficient pollen dissemination on stigma. Meanwhile, low temperature stress also reduces pollen viability and germination ability, and directly affects fertilization and seed setting, which is one of the major reasons for reducing seed setting rate.