Table of Content

12 September 2015, Volume 41 Issue 09

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

RNA Interference of OsGABA-T1 Gene Expression Induced GABA Accumulation in Rice Grain

ZHOU Lu, SHEN Bei-Bei, BAI Su-Yang, LIU Xi, JIANG Ling, ZHAI Hu-Qu, WAN Jian-Min

Acta Agron Sin. 2015, 41(09):  1305-1312.  doi:10.3724/SP.J.1006.2015.01305

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γ-Aminobutyric acid (GABA) is a four-carbon non-protein amino acid and has been identified to have a function in reducing blood pressure. In order to increase GABA contents in rice grains, we constructed a RNA interference (RNAi) vector suppressing the expression of GABA transaminase 1 gene (OsGABA-T1). GABA transaminase is a key enzyme that converts GABA to succinate semialdehyde (SSA). The RNA interference vector was transformed into the callus of japonica cv. Ningjing 1. qRT-PCR analysis showed that OsGABA-T1 transcript abundance in the RNAi transgenic lines was effectively reduced, so did the homolog gene OsGABA-T2. The GABA contents of brown rice in T₃ generation of RNAi lines were 13 times higher than these in Ningjing 1, so did in polished rice as well as brown rice and polished rice stored for four months of post-harvest in transgenic rice, while other main amino acid contents did not change much. In summary, this research provides a basis for breeding a rice variety which could contribute to reduce blood pressure due to the enrichment of GABA contents in rice seeds though effectively suppressing the expression of OsGABA-T1 gene by the RNA interference technique.

Mapping of QTLs for Pod Size Related Traits in Cultivated Peanut (Arachis hypogaea L.)

LI Zhen-Dong, LI Xin-Ping, HUANG Li, REN Xiao-Ping, CHENG Yu-Ning, ZHOU Xiao-Jing, LIAO Bo-Shou, JIANG Hui-Fang

Acta Agron Sin. 2015, 41(09):  1313-1323.  doi:10.3724/SP.J.1006.2015.01313

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One hundred and eighty-eight recombinant inbred lines (RIL), derived from a cross between two Spanish type peanut cultivars (Yuanza 9102 × Xuzhou 68-4), were used as mapping population. Finally, a genetic linkage map consisting of 443 SSR loci in 22 linkage groups and covering 713.07 cM with an average distance of 1.96 cM was constructed. The length of linkage group was from 12.37 cM to 81.39 cM and the number of markers was 3-46. QTL mapping of the traits related to pod was conducted by using CIM model in WinQTLcart 2.5. A total of 41 QTLs were detected in the two environments, including thirteen for pod length, seven for pod width, thirteen for pod thickness and right for hundred pod weight, every single QTL explained 3.14%-18.27% of the phenotypic variation. A total of six QTLs were detected in both environments, including three for pod length with explained phenotypic variance of 3.14%-18.27% on the linkage group 2, linkage group 13 and linkage group 14. One for pod thickness with explained phenotypic variance of 8.24%-9.24% on the linkage group 3, and two for hundred pod weight with explained phenotypic variance of 6.95%-14.60% on the linkage group 13 and linkage group 14. The result showed that there were nine hotsports for QTL research, and each of them was associated with 2-3 traits, explaining 3.57%-18.27% of the phenotypic variation.

cDNA Cloning and Analysis of Cinnamoyl-CoA Reductase Gene from Boehmeria nivea

TANG Ying-Hong, CHEN Jian-Rong, LIU Fang, YUAN You-Mei, GUO Qing-Quan, CHANG Hong-Tao

Acta Agron Sin. 2015, 41(09):  1324-1332.  doi:10.3724/SP.J.1006.2015.01324

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Two cDNA sequences of cinnamoyl-CoA reductase genes were cloned by RACE technology base on transcriptome sequencing data of Boehmeria nivea, and their bioinformatics were analyzed. Their expression levels in tissues of phloem and xylem were also tested respectively in rapid-growth stage, maturation stage and late maturity stage by quantitative Real-time PCR. The results showed that the BnCCR1 was 1056 bp in length and encoding 277 amino acids. Blast and protein structure analysis showed that its cDNA sequence shared a homology of 70% compared with Betula platyphylla and Ricinus communis CCR, and its amino acids did a homology of 77% compared with that of Ricinus communis. Protein prediction showed its protein N terminal with a conservative field of 3 Beta-HSD/Epimerase/NAD-binding-10. The coding sequence of BnCCR2 gene was 1291 bp, and could be translated into a 248 amino acids. Blast and protein structure analysis showed that its cDNA sequence had a homology of 74% compared with Populus trichocarpa CCR, and its amino acids had a homology of 81% compared with these of Ricinus communis and Populus trichocarpa. Protein prediction showed its protein N terminal with a conservative field of 3 Beta-HSD/ Epimerase/NAD-binding-4. Three-dimensional structures of BnCCR1 and BnCCR2 had relatively high similarity with CCR genes in petunias, and the similarity was 30.68% and 44.77% respectively. The result of qRT-PCR indicated that the expression of both BnCCR1 and BnCCR2 was different in different periods, while not in different tissues, but the levels of expression in different tissues showed significant differences. We speculated that BnCCR1 and BnCCR2 are different CCR genes in lignin metabolism of Boehmeria nivea, and the result of this study provide a theoretical basis for further exploration of their function in the ramie lignin biosynthesis and regulation.

Genetic Analysis of Yield and Physiological Traits in Elite Parent Jing 411 and Its Derivatives under Two Fertilization Environments

XIAO Yong-Gui, LI Si-Min, LI Fa-Ji, ZHANG Hong-Yan, CHEN Xin-Min, WANG De-Sen, XIA Xian-Chun, HE Zhong-Hu

Acta Agron Sin. 2015, 41(09):  1333-1342.  doi:10.3724/SP.J.1006.2015.01333

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Understanding the genetics of the traits related to yield potential, stability and high fertilizer-use efficiency is important for breeding new varieties. The elite parent Jing 411 has been widely used in wheat breeding programs in Northern Winter Wheat Region. In this study, Jing 411 and its 14 derivatives were sown in normal fertilized and no-fertilized environments to assess the changes in yield stability and fertilizer-use efficiency. Grain yield and harvest index increased following the generation advance, particularly harvest index increased significantly (P < 0.05). Zhongmai 175 showed high and stable grain yield and above ground biomass under two fertilized environments, mainly due to its high fertilizer-uptake efficiency. Canopy temperature was significantly associated with grain yield (P < 0.05), and leaf area index, and photosynthetic rate were significantly correlated with harvest index (P < 0.05). Several important loci associated with yield and physiological traits were found in A and B genomes. Three new loci for grains per spike, leaf area index, and photosynthetic rate were detected on chromosomes 2B, 3A, and 5A, respectively. Furthermore, 31 positive genetic loci for yield and physiological traits were detected in elite parent Jing 411, and two derivatives, CA0958 and Zhongmai 175, had the most positive loci than others, accounting for 53.85% and 51.35%, respectively. Zhongmai 175 had higher yield potential and stability under different fertilizer environments, possibly due to the presence of positive loci for yield and physiological traits.

Cloning and Functional Analysis of Glycine soja Bicarbonate Stress Responsive Gene GsMIPS2

CHEN Chen, SUN Xiao-Li, LIU Ai-Lin, DUAN-MU Hui-Zi, YU Yang, XIAO Jia-Lei, ZHU Yan-Ming

Acta Agron Sin. 2015, 41(09):  1343-1352.  doi:10.3724/SP.J.1006.2015.01343

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To identify the key functional genes in response to bicarbonate stress in Glycine soja L. G07256, we constructed a gene expression profile under bicarbonate treatment using high throughput RNA-seq data, from which we selected a myo-inositol- 1-phosphate synthase gene whose expression was significantly induced by bicarbonate stress. By homology-based cloning, we acquired its full length cDNA and termed as GsMIPS2. The results of quantitative real-time PCR demonstrated the bicarbonate stress induced expression of GsMIPS2 and its tissue expression specificity. We also verified the function of GsMIPS2 in bicarbonate responses by using the GsMIPS2 transgenic Arabidopsis combined with the T-DNA insertion line atmips2. We revealed that the germination rate of GsMIPS2 overexpression lines was significantly higher, while that of atmips2 mutant line was much lower than that of wild type under bicarbonate stress. These results indicate the positive role of GsMIPS2 in plant bicarbonate stress responses.

Enzymatic Characteristics of Acetolactate Synthase Mutant S638N in Brassica napus and Its Resistance to ALS Inhibitor Herbicides

HU Mao-Long, PU Hui-Ming, LONG Wei-Hua, GAO Jian-Qin, QI Cun-Kou, ZHANG Jie-Fu, CHEN Song

Acta Agron Sin. 2015, 41(09):  1353-1360.  doi:10.3724/SP.J.1006.2015.01353

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Acetolactate synthase (ALS) catalyses the first step in the synthesis of the branched-chain amino acids and is the target of several classes of herbicides. A BnALS1R gene from herbicide-resistant mutant line M9 in B. napus, was previously isolated and demonstrated to be resistant to the imidazolinone (IMI) herbicides. This research was to reveal the differences of enzymatic characteristics and its resistance to ALS inhibitor herbicides between the mutant S638N and the wild-type enzyme. The BnALS1R gene was constructed and expressed in Escherichia coli along with the wild-type. The target recombinant proteins with the predicted molecular weight (74 kD) were successively expressed in Escherichia coli and purified by SDS-PAGE. The enzymatic activity of the purified S638N and wild-type was then measured in enzyme reaction systems under different temperatures and pH values. Results showed that the S638N resembled the wild-type in their enzymatic activity, showing maximum activity at 37°C and pH 7.0, and no significant difference in the K_m and V_max between the S638N and wild-type. The activation of the S638N by cofactors (FAD, Mg²⁺ and thiamine diphosphate) was examined and generated similar results to that of the wild-type. The mutant enzyme was inactive when one of three cofactors was omitted. However, the S638N was more resistant to IMI herbicides than the wild-type in contrast to Su herbicides that inhibited the S638N as well as the wild-type. Therefore, the S638N has resistance specific to IMI herbicides with unalteration of the enzymatic reaction characteristics.

Molecular Cloning and Functional Analysis of Polygalacturonase-Inhibiting Protein Gene MaPGIP1 from Mulberry (Morus atropurpurea Roxb.)

WANG Xiao-Hong, ZHU Pan-Pan, LIANG Yan-Mei, HAN Shu-Mei, ZHAO Ai-Chun, WANG Chuan-Hong, LU Cheng, YU Mao-De

Acta Agron Sin. 2015, 41(09):  1361-1371.  doi:10.3724/SP.J.1006.2015.01361

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Polygalacturonase-inhibiting protein (PGIP) is a defense protein found in plant cell wall. It is involved in plant defense against infection of pathogens by modulating/inhibiting the activity of endo-polygalacturonase. In this test, a pair of specific primers were designed based on PGIP genes of mulberry (Morus notabilis) in Morus Genome Database. The cDNA of Jialing 40 PGIP gene was amplified from fruit by RT-PCR. The sequences of mulberry PGIP, physic-chemical parameters of PGIP protein and phylogenetic relationship were analyzed by bioinformatics softwares. Using pET-28a(+) as a fused expression vector, a recombinant plasmid pET28a-PGIP containing the mature peptide of PGIP was constructed. Then its expression was induced in Escherichia coli BL21 (DE3) with IPTG. The samples induced at different times were collected and SDS-PAGE was used to analyze the protein expression in E. coli BL21 (DE3). After purification of the protein by Ni-Hind affinity column and Western blot, the PGIP gene expressed in E. coli BL21 (DE3). Finally its enzymatic activity was tested by bacteriostatic experiment. The full-length cDNA of PGIP from Jialing 40 fruit was obtained. Sequence analysis showed that the fragment contains an open reading frame of 1017 bp encoding 338 amino acid residues with a molecular mass of 37.9 kD, named MaPGIP1. This deduced protein has a pI of 6.65, a hydrophobic region of 26 amino acid residues in the N-terminal which was considered to be a signal peptide, with four potential N-glycosylation sites, and it center LRR structural domain is composed of nine tandem LRR motifs. Phylogenetic tree showed that Jialing 40 had the closest evolutionary relationship with M. notabilis. The prokaryotic expression results showed that efficient expression of PGIP protein could be realized after induction with 0.5 mmol L^-1 IPTG in E. coli BL21 (DE3) for five hours at 28 °C. The SDS-PAGE displayed that the recombinant proteins only appeared as inclusion bodies. The inclusion bodies protein was purified by Ni-NTP affinity column and confirmed by Western blot. Soluble product could be refolded though stepwise dialysis strategies. The recombinant protein concentration was 0.58 μg μL^-1 tested by Bradford method. MaPGIP1 partially inhibited CsPG with an optimum pH between 4.5 and 5.0, and an optimum temperature of 30°C. The preliminary infection experiment result showed that MaPGIP1 protein after renaturation had a certain inhibiting effect on Hypertrophy Sorosis Sclerotenisis infected by Ciboria shiraiana.

Genetic Analysis and QTL Mapping of Isoflavone Contents and Its Components in Soybean

LIANG Hui-Zhen, YU Yong-Liang, YANG Hong-Qi, XU Lan-Jie, DONG Wei, NIU Yong-Guang, ZHANG Hai-Yang, LIU Xue-Yi, FANG Xuan-Jun

Acta Agron Sin. 2015, 41(09):  1372-1383.  doi:10.3724/SP.J.1006.2015.01372

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A set of 447 recombinant inbred lines (RILs) derived from the cross between cultivars Jingdou 23 (female parent) and Huibuzhi (semi-wild, male parent) was used to construct a new map. Isoflavone content and its components were quantitatively and qualitatively evaluated by using high performance liquid chromatography (HPLC). We analyzed inheritance and detected QTLs for isoflavone content and its components in soybean seeds using major gene plus polygene mixed inheritance analysis and WinQTLCart 2.5 composite interval mapping. The results showed that daidzin, daidzein, genistein, genistin, glycitin, and total isoflavone contents were controlled by four, four, two, three, two and two main-genes, respectively. However, polygene effects were not detected in the study. Forty-four quantitative trait loci (QTLs) for isoflavone contents and its components were mapped, including ten for daidzin, nine for genistein, four for daidzein, seven for glycitin, eight for genistin, and six for total isoflavone content. The stable QTLs related to daidzin, genistin, glycitin, isoflavone content were respectively detected to be located in the intervals of satt430-satt359, satt038-satt570, satt197-sat_128, and satt249-satt285 during two years, which could be used in marker-assisted selection (MAS) for soybean breeding.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Row Orientation on Leaf and Stalk Morphogenesis and Grain Yield in Maize

WANG Qing-Yan, YE De-Lian, ZHANG Yu-Shi, LI Jian-Min, ZHANG Ming-Cai, LI Zhao-Hu

Acta Agron Sin. 2015, 41(09):  1384-1392.  doi:10.3724/SP.J.1006.2015.01384

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A field experiment was conducted in 2012-2013 to investigate the effects of row orientation on plant morphological parameters and grain yield in maize (Zea mays L., cv. Zhengdan 958). The results showed that leaf elongation and leaf area from the 11th to the 17th leaf increased significantly in east-west (E-W) row orientation compared to north-south (N-S) row orientation, whereas, the leaf width was not affected. In the E-W treatment, elongations of 7th-13th internodes and the maximum diameters of 9th-13th internodes were improved significantly. Simultaneously, dry weight per millimeter internode and stem lateral breaking strength of the 9th and the 10th internodes increased significantly in the E-W treatment. At jointing stage, biomass accumulations in both row orientations were similar. However, biomass accumulation per plant was significantly higher in the E-W treatment than in the N-S treatment from ear developing to mature stage. The assimilate transfer from leaves and internodes to kernels was also improved in the E-W treatment, leading to higher 1000-kernel weight, kernel yield, and harvest index in E-W than in N-S row orientation. These results suggest that E-W row orientation is applicable in high-yield maize production in North China.

Comparison of Yield and Light-temperature Resource Use Efficiency between Wheat-Maize and Maize-Maize Cropping Systems

ZHOU Bao-Yuan, WANG Zhi-Min, YUE Yang, MA Wei, ZHAO Ming

Acta Agron Sin. 2015, 41(09):  1393-1405.  doi:10.3724/SP.J.1006.2015.01393

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Optimizing traditional wheat-maize cropping and exploring new cropping system are essential for increasing annual yield and resource use efficiency in the Yellow-Huaihe-Haihe Rivers Plain. The optimized winter wheat-summer maize cropping (T1) and double maize cropping (T2) were established in our field experiment conducted in Xinxiang from 2009 to 2012. The dry matter production, grain yield, and energy (light and temperature) use efficiency were investigated in the two cropping systems and compared with those in traditional cropping system (CK). In the two optimized cropping systems, the distributions of light and temperature between two cropping seasons were adjusted to 0.7:1.0 and 1.4:1.0 in T1 cropping system, and 1.5:1.0 and 1.0:1.0 in T2 cropping system, respectively, by changing the sowing and harvest dates. Under T1 condition, the annual yield increased by 7.8% over that of CK (P < 0.05), and the yield promotion was mainly attributed to the significant increase in the summer maize season. Late sowing of winter wheat in T1 system resulted in significant improvements of mean leaf area index (MLAI), above-ground biomass, and grain yield of summer maize, meanwhile with no significant yield loss of winter wheat. T2 is a new high-yield production pattern with double maize growing seasons. In the first season, the MLAI, above-ground biomass, and yield of maize were significantly higher than those of winter wheat in CK and T1. In the second season, the above-ground biomass, and yield of T2 were lower than those of CK and T1. However, the annual yield of T2 was higher than that of CK and had no significant difference to that of T1. Compared to CK and T1, T2 resulted in increases by 53.9% and 46.2% in daily yield, 30.5% and 23.3% in light production efficiency, 15.5% and 9.7% in temperature production efficiency, and 30.3% and 23.0% in light energy use efficiency, respectively. These results indicate that the advantages of high resource use efficiency and production capabilities of C₄ crop plays the key role in promoting the annual production capability in T1 and T2. The two optimized cropping systems (T1 and T2) may lighten the thoughts for adjusting production patterns to meet an increasing desire of high yield and resource use efficiency in the Yellow-Huaihe-Haihe Rivers Plain.

Effects of Coupling Controlled Release Urea with Water on Yield and Photosynthetic Characteristics in Summer Maize

LI Guang-Hao, ZHAO Bin, DONG Shu-Ting, LIU Peng, ZHANG Ji-Wang, HE Zai-Ju

Acta Agron Sin. 2015, 41(09):  1406-1415.  doi:10.3724/SP.J.1006.2015.01406

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A experiment using Zhengdan 958 (a summer maize cultivar planted widely in China), with treatments of three water levels (normal water W3, mild water stress W2, severe water stress W1) and four amounts of controlled release urea nitrogen (N) (N3 was 315 kg ha^-1, N2 was 210 kg ha^-1, N1 was 105 kg ha^-1 and N0 was no nitrogen) was carried out under the waterproof shed and potting conditions. The results showed there was significant influence of coupling water with controlled release urea on yield and photosynthetic characteristics in summer maize. Under the condition of same soil moisture, the yield showed a increasing trend with the amounts of N application increased. The yield increased by 13.17%-20.96% under severe water stress (W1), by 13.93%-32.48% under mild water stress (W2), and by 14.37%-21.83% under the condition of normal water (W3). Under the same amounts of N application, the yield was also improved with the increase of the soil moisture. The yields of W2N3, W3N2, and W3N3 were the highest among these treatments. The coupling effects of water and controlled release urea were significant on the photosynthetic rate in ear leaf. The photosynthetic rates of N3, N2, and N1 had no significant differences in W1, and were higher than these of N0 significantly. The photosynthetic rate of W2 and W3 treatments increased with the increase of N fertilizer application, the average photosynthetic rate in W3 was higher than that of W2 and W1, that of W2N3 was slightly lower than that of W3N3 and W3N2 at early flowering, and no significant difference in the late stage. The coupling effects of water and controlled release urea nitrogen could effectively improve the efficiency of light energy utilization and slow down the decline rates of the actual photochemical efficiency of PSII, coefficient of photochemical quenching (q_P) of leaf and PSII reaction center of light conversion. High photosynthetic rate, actual and maximal photochemical efficiency of ear leaf after flowering in summer maize ensured the nutrients needs of grain filling, thus increased the yield. Higher yield was obtained due to the significant increase of kernels per ear and thousand seed weight among yield components. Under this experimental condition, controlled release urea N application rate of 210 kg ha^-1 was the best treatment as the soil moisture content was 75%±5% of field capacity. We suggested that coupling controlled release urea N application rate of 315 kg ha^-1 with soil moisture content of 55%±5% of field capacity is optimum.

Effects of N, P, and K Fertilizers on Silique Shatter Resistance and Related Traits of Rapeseed

LIU Ting-Ting, KUAI Jie, SUN Ying-Ying, YANG Yang, WU Lian-Rong, WU Jiang-Sheng, ZHOU Guang-Sheng

Acta Agron Sin. 2015, 41(09):  1416-1425.  doi:10.3724/SP.J.1006.2015.01416

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To study the effects of the farming measures on silique shatter resistance of rapeseed, we designed different fertilizer application combinations of N (0, 90, 180, 270, and 360 kg N hm^-2), P (0, 60, 120, 180, and 270 kg P₂O₅ hm^-2) and K (0, 75, 150, 225, and 300 kg K₂O hm^-2) with two varieties for better machinery harvest. Results showed that with the increase of N, P and K fertilizer application rates, the silique shatter resistance index (SRI) of the two varieties changed as a multi-peak curve. The highest SRI of Huashuang 5 was reached under application of 160 kg N hm^-2, 120 kg P₂O₅ hm^-2 and 180 kg K₂O hm^-2, while that of Huahang901 was under application of 140 kg N hm^-2, 160 kg P₂O₅ hm^-2 and 180 kg K₂O hm^-2. The change degree in SRI differed due to different fertilizers, and K fertilizer had the greatest effect on the SRI of the two varieties among N, P and K fertilizers. The silique wall weight and plant height under different N, P and K fertilizer rates were the key factors affecting rapeseed’s SRI, and could be used as important indexes in silique shatter resistance screening.

Effects of Legumes Intercropping with Oat on Photosynthesis Characteristics of and Grain Yield

FENG Xiao-Min, YANG Yong, REN Chang-Zhong, HU Yue-Gao, ZENG Zhao-Hai

Acta Agron Sin. 2015, 41(09):  1426-1434.  doi:10.3724/SP.J.1006.2015.01426

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Intercropping, a commonly used agronomic management by farmers in China for centuries can improve light, heat, water and nitrogen utilization efficiencies and significantly enhance crop yield. To reveal the mechanism of photosynthesis in soybean-oat and peanut-oat intercropping systems, we conducted a two-year (2011, 2012) field experiment in Baicheng, Jilin province. Under the nitrogen-free condition, crop yield, yield components and photosynthesis and relative chlorophyll content (SPAD) of functional leaves in crops were investigated during growth stage. The results showed that land equivalent ratio (LER) was from 1.41 to 1.63 and from 1.31 to 1.52 for soybean-oat and peanut-oat intercropping, respectively. Also, most yield components from oat (plant height, spike length and spikelet, grain number per spike) under intercropping with soybean were higher than those from mono-cropping oat, except for grain weight per plant and thousand seed weight. Under intercropping with peanut, all yield components of oat increased in comparison with those under mono-cropping oat and spikelet, grain number per spike and grain weight per plant showed significant difference. Moreover, all yield components of soybean intercropping with oat improved, whereas decreased peanut pod number and grain weight per plant. As for photosynthesis, intercropping enhanced chlorophyll content and net photosynthetic rate of oat and altered chlorophyll composition which contributed to the slower process of oat aging. With regard to peanut, chlorophyll content slightly increased when intercropped with oat and net photosynthetic rate significantly improved during the late booting stage to heading stage of oat. In conclusion, under the condition of nitrogen-free, intercropping is demonstrably superior to monoculture. The peanut-oat intercropping system notably promotes the growth of oat, while the oat and soybean are both benefit from the soybean-oat intercropping system.

Modeling of Biomass-Based Leaf Morphological Parameters on Main Stem for Rapeseed (Brassica napus L.)

ZHANG Wen-Yu, ZHANG Wei-Xin, GE Dao-Kuo, CAO Hong-Xin, LIU Yan, XUAN Shou-Li, FU Kun-Ya, FENG Chun-Huan, CHEN Wei-Tao

Acta Agron Sin. 2015, 41(09):  1435-1444.  doi:10.3724/SP.J.1006.2015.01435

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To quantify the relationships between main stem leaf morphological parameters for rapeseed and the corresponding leaf biomass, we conducted field experiments on varieties, transplanting densities, and fertilizer in 2011 to 2012, and 2012 to 2013 seasons. The biomass-based leaf morphological parameter models for rapeseed on main stem were constructed through observing leaf length, maximum leaf width, and leaf petiole length under various treatments, and analyzing the relationships between leaf morphological parameters and the corresponding leaf biomass. Because both of the leaf length and leaf width were positively proportional to the square root of the corresponding leaf biomass, meanwhile the leaf petiole length was positively proportional to the corresponding leaf length, the changes in the leaf length, the maximum leaf width, and the leaf petiole length with the changed of square root of the corresponding leaf biomass for different treatments could be described with linear function. The biomass-based leaf morphological parameter models were validated using independent experiment data, and the results showed that the model revealed satisfactory predictions of leaf length, leaf width, and leaf petiole length, except the simulation for leaf petiole length of Ningyou 16. The research provides a mechanistic method for linking the rapeseed growth model with the morphological model using organ biomass, and lays a foundation for the establishment of functional-structural plant models of rapeseed.

RESEARCH NOTES

Overexpression of Millet Transcription Factor Gene SiNAC45 to Response of Low Potassium Stress and ABA Treatment in Transgenic Arabidopsis

WANG Er-Hui, HU Li-Qin, XUE Fei-Yang, LI Wei-Wei, XU Zhao-Shi, LI Lian-Cheng, ZHOU Yong-Bin, MA You-Zhi, DIAO Xian-Min, JIA Guan-Qing, CHEN Ming, MIN Dong-Hong

Acta Agron Sin. 2015, 41(09):  1445-1453.  doi:10.3724/SP.J.1006.2015.01445

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NAC (nascent polypeptide-associated complex) like transcription factors play important role in plant growth and development, abiotic stress response, and other processes. Currently, few researches reported NAC like transcription factors involving in tolerance to low potassium stress. In this study, we found and researched a NAC like transcription factor gene SiNAC45 on the basis of transcriptome sequence of millet under low potassium stress which had been completed in previous work. The result show that the full-length of SiNAC45 is 1383 bp, encoding 461 amino acids, with molecular weight and isoelectric point of 50.7 kD and 6.92, respectively. There is a conserved NAM domain between 20-100 amino acids of SiNAC45. The phylogenetic tree showed that SiNAC45 belonged to the first subfamily of NAC gene family. The gene expression profile results indicated SiNAC45 mainly expressed in roots and was induced by ABA and low potassium treatment. The protein subcellular localization results of SiNAC45 revealed that it was localized in the nucleus. Gene functional analysis showed that under treatment with different concentrations of potassium, root length and fresh weight of SiNAC45 transgenic Arabidopsis significantly increased compared with those of wild-type Arabidopsis, and there was no significant difference in the number of lateral roots between transgenic and wild-type Arabidopsis, indicating that overexpressing of SiNAC45 in transgenic plants can enhance tolerance to low potassium stress. Expression analysis of downstream gene showed that expression of two important potassium transporter genes AKT1 and HAK1 increased significantly in SiNAC45 transgenic plants, indicating that SiNAC45 affects the tolerance to low potassium stress of plants by regulating the expression of potassium transporter gene. Seed germination test results showed that Arabidopsis carrying SiNAC45 decreased the sensitivity to ABA compared with wild-type Arabidopsis, indicating that SiNAC45 maybe negatively regulate ABA signal pathway.

Screening of Methyl Jasmonate-Insensitive Mutants in Maize

ZHA Xiang-Min, WANG Hai, LU Xiao-Duo, ZHANG Chun-Yi, HUANG Da-Fang, LANG Zhi-Hong

Acta Agron Sin. 2015, 41(09):  1454-1461.  doi:10.3724/SP.J.1006.2015.01454

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The phytohormone jasmonate plays a pivotal role in plant systematic resistance to herbivores attack as a long-distance mobile signal. To demonstrate the Jasmonic acid (JA) signal pathway and the insect-resistant mechanism in maize, we utilized an improved approach to screen the maize mutants associated with JA signal pathway, which will be available for further research. The 6118 lines’ seeds from EMS-mutagenic maize mutants library were cultivated in the medium containing the exogenous MeJA. The different tolerances of the mutants to MeJA were identified by observing the growth of maize roots. When the final concentration of MeJA was 50 µmol L^-1, 61 MeJA-insensitive mutants with tolerance Grade I were obtained in the primary screening experiment. When the final concentration of MeJA was 100 µmol L^-1 or 200 µmol L^-1, 37 and 10 tolerant events were gained in the confirmation experiments, respectively. Then, we analyzed the heredity of M1 seeds tolerant to MeJA. The results showed that the tolerance of the mutants to MeJA was hereditable. The MeJA-insensitive mutants associated with JA regulation pathway are the potential materials for the further studies of JA signal pathway and insect resistant mechanism in maize.