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OsMAX1a and OsMAX1e, Involved in the Biosynthesis of Strigolactones,Regulate Rice Tillering Xiu-mei WANG, Yue-yang LIANG, Ling LI, Chang-wei GONG, Hai-peng WANG, Xiao-xi HUANG, Shuang-cheng LI, Qi-ming DENG, Jun ZHU, Ai-ping ZHENG, Ping LI, Shi-quan WANG 2015, 29(3): 223-231.  DOI: 10．3969/j．issn．1001G7216．2015．03．001 Abstract ( )   HTML ( )   PDF (2781KB) ( )   Strigolactones (SLs) are a class of phytohormone which play essential roles in regulating rice tillering, and ATMAX1 in Arabidopsis encodind P450 is an important gene involved in the synthesis of SLs.Our study found five MAX1 homologous genes through BLAST, namely OsMAX1a, OsMAX1b, OsMAX1c, OsMAX1d and OsMAX1e. Among them, OsMAX1a and OsMAX1e have stable and high expression in rice tissues. Our experiments verified that the overexpression of OsMAX1aand OsMAX1e in Arabidopsis rescued the max1 branched mutant phenotype, and the interference of OsMAX1a and OsMAX1e expression in rice increased rice tillering number. Furthermore, enogenous GR24 application inhibited the expression of OsMAX1a and OsMAX1e, and P-starvation enhanced the expression of OsMAX1a and OsMAX1e,thus promoted the biosynthesis of SLs. In addition, IAA and Kinetin(a cytokinin:KT) treatment apparently had remarkable effect on the expression of OsMAX1a and OsMAX1e. The results demonstrated that the expression of OsMAX1a and OsMAX1e responded to the SLs level and they were involved in the synthesis of SLs and regulated rice tillering.

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Dissection of Quantitative Trait Loci for Grain Weight and Its Component Traits in the qTGW1.2 Region on Chromosome 1 of Rice Lin-lin WANG, Yu-yu CHEN, Liang GUO, Hong-wei ZHANG, Ye-yang FAN, Jie-yun ZHUANG 2015, 29(3): 232-240.  DOI: 10．3969/j．issn．1001G7216．2015．03．002 Abstract ( )   HTML ( )   PDF (1929KB) ( )   This paper reports the dissection of three quantitative trait loci(QTLs)for 1000-grain weight (TGW),grain length(GL)and grain width (GW) on the long arm of chromosome 1 in rice. A plant carrying a heterozygous segment extending from RM212 to RM265 was selected from the Zhenshan 973/Milyang 46 BC2F8 population. The resulting BC2F9 population was assayed with DNA markers. Two plants were identified,carrying heterozygous segments covering the intervals RM212-RM11787 and RM11787-RM265 which were previously found to harbor qTGW1.2a and qTGW1.2b for TGW,respectively. Two BC2F10 populations were produced,from which three plants with sequential heterozygous regions were identified,respectively. Using the six BC2F11 populations derived,a QTL for GL was detected in the interval RM11730-RM11800, and the regions for qTGW1.2a and qTGW1.2b were narrowed down to the 580 kb interval RM11730-Wn33304 and 2.0 Mb interval RM11807-RM11885,respectively. In the meantime,five plants with smaller heterozygous regions were selected,from which five BC2F12 populations were constructed. A QTL for GL was detected in each of the five populations. The additive effect ranged from 0.03 mm to 0.06 mm with the enhancing alleles derived from Milyang 46. Based on comparison of the segregating regions among the five populations,qGL1.2 for GL was delimited to a 372 kb region flanked by RM11781 and Wn34526. This QTL had the additive genetic action mode and may simultaneously affect TGW, GL and GW.

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Genetic Analysis and Gene Mapping of a Yellow-green Leaf Mutant w390 in Rice (Oryza sativa L.) Qing DONG, Ying-xin ZHANG, Zhen-hua ZHANG, Quan ZHOU, Ya-zhi QIN, Hong WANG, Shi-hua CHENG, Li-yong CAO, Xi-hong SHEN 2015, 29(3): 241-249.  DOI: 10．3969/j．issn．1001G7216．2015．03．003 Abstract ( )   HTML ( )   PDF (2129KB) ( )   A yellow-green leaf mutant, designated as w390, was isolated from the progeny of 60Co-γ-treated indica cultivar R8015. The mutant exhibited a stable yellow-green leaf phenotype during the whole life cycle. The chlorophyll b was not detected in w390, and the chlorophyll a and carotenoids contents of w390 were reduced by 50.6% and 44.8%, compared with the wild-type. The plant height, the number of panicle per plant, the number of spikelets per panicle, the number of grains per panicle of w390 were reduced by 12.0%, 22.3%,18.5% and 27.6%, respectively. The transmission electron microscope assay demonstrated that the number of thylakoids decreased and granas were poorly stacked in the mutant, resulting in underdevelopment of chloroplasts. Genetic analysis showed that the yellow-green leaf phenotype was controlled by a single recessive gene. Using an F2 mapping population derived from the cross of w390 mutant and Nipponbare, the gene was delimitated to a region of 71.8-kb on the long arm of chromosome 10, which contained 15 ORFs. Sequence analysis revealed that the mutant carried two nucleotide substitutions in the eighth exon of OsCAO1 gene, which led to the substitution of leucine and glycine for histidine and glutamic acid, respectively. This implied that W390 might be a novel allele of OsCAO1 gene.

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Aluminium Tolerance of OsPIN2 Overexpressed Rice Seedlings under Pot Culture Dao-ming WU, Hua-ping CAO, Xiao-li YU, Hong SHEN 2015, 29(3): 250-258.  DOI: 10．3969/j．issn．1001G7216．2015．03．004 Abstract ( )   HTML ( )   PDF (1769KB) ( )   Differences in Al tolerance of OsPIN2 overexpressed rice seedlings (OXs) and its wild-type (WT) were investigated in 20% and 55% Al saturated soils in a pot experiment. Results indicated that in 55% Al-saturated soil, growth of root and shoot of rice seedlings was inhibited, the first tillering time was delayed, and tiller angle and numbers were reduced. OXs showed less growth inhibition both in roots and shoots than those of WT. More tiller numbers and larger tiller angles were also found in OXs than those in WT. Moreover, the contents of phosphorus, calcium and magnesium in the shoots of OXs were 1.71, 1.25 and 1.32 times of those of WT, respectively. In comparison to WT, OXs accumulated less Al in the roots, root-shoot injunction and stems, and 28.5%-109.8% more Al in the leaves. These results suggest that overexpressing of OsPIN2 in rice seedlings enhance the uptake of phosphorus, calcium and magnesium, reduce Al accumulation in roots and root-shoot injunction, and thus alleviate the toxicity of Al to rice roots and tillering under Al stress.

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Effect of Cold-Water Irrigation at Booting Stage on Grain Filling and Nitrogen Accumulation of Rice in Cold-Region Yan JIA, Yang SHEN, De-tang ZOU, Han-jing SHA, Jing-guo WANG, Hua-long LIU, Zhen-dong ZHAO, Nan XIA, Hong-wei ZHAO 2015, 29(3): 259-272.  DOI: 10．3969/j．issn．1001G7216．2015．03．005 Abstract ( )   HTML ( )   PDF (2574KB) ( )   In order to understand how cold-water irrigation at booting stage affects the dry matter and nitrogen accumulation of grain in rice in cold-region, two japonica rice (Dongnong 428 and Songjing 10) were subjected to cold water irrigation for 6 varying length of time (0, 3, 6, 9,12 and 15 d) at booting stage. The dry matter, nitrogen accumulation and enzyme activities involved in nitrogen metabolism of grain were measured,respectively. The results showed that grain dry matter accumulation and yield in rice in cold-region followed a similar trend, and decreased under cold-water irrigation at booting stage with increasing cold-water irrigation days compared with the control. Due to the decreased maximum accumulation rate, seed setting rate, productive panicle number, grain number per panicle, grain dry matter accumulation decreased. The total nitrogen, protein nitrogen of grain, protein content of mature grain, and glutamine synthetase activity at early grain filling stage increased under cold-water irrigation. The gutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase activities in grain significantly increased under 6 d of cold-water irrigation, whereas significantly decreased under 9-15 d of cold-water irrigation. The increase in total and protein nitrogen contents was due to the enhancement of grain nitrogen assimilation and protein synthesis ability under short term (3-6 d) cold-water irrigation, however, the process of nitrogen assimilation was inhibited, affecting the synthesis of protein and amino acid, eventually leading to a reduction in the growth rate of grain nitrogen content under long term(9-15 d) cold-water irrigation. Given grain total nitrogen, protein nitrogen and granule starch protein content varied with cold-water treatment duration and cultivar, they can be used as comprehensive evaluation indicators for cold resistance.

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Difference in Lodging Resistance of Culm Between indica and japonica Super Rice Jin-long GONG, Zhi-peng XING, Ya-jie HU, Hong-cheng ZHANG, Qi-gen DAI, Zhong-yang HUO, Ke XU, Hai-yan WEI, Hui GAO 2015, 29(3): 273-281.  DOI: 10．3969/j．issn．1001G7216．2015．03．006 Abstract ( )   HTML ( )   PDF (689KB) ( )   To reveal the difference in lodging resistance of culm between indica and japonica super rice, a field experiment was conducted by using two main representative super hybrid indica combinations and two conventional japonica super rice varieties as materials in the rice-wheat cropping regions. Characteristics of morphology, Filling and mechanics, breaking resistance, bending moment, lodging index, apparent lodging rate in the field and grain yield were analyzed systematically. Results showed that: 1) grain yield of japonica rice was significantly higher than that of indica rice, with a rate of 12.30%. For the culm of 0-20 cm from the bottom, the bending moment of japonica rice was significantly higher than indica rice and the lodging index followed an opposite trend without lodging, compared to the average apparent lodging rates in the field of 11.97%, 12.50% from 2011 to 2012 for Yangliangyou 6 and Liangyoupeijiu, respectively. 2) For all the four basal internodes, indica rice had significantly higher breaking resistance and lodging index, while bending moment followed an opposite tendency. 3) Length of each internode and plant height, outer diameter of basal internode, stalk type index, single panicle weight, height of gravity center and ratio of gravity center height to plant height of japonica rice were lower than that of indica rice significantly, with an opposite trend for ratio of neck internode length to stalk length. 4) Culm diameter and wall thickness for all the six elongated internodes of japonica rice were less than that of indica rice, with culm diameter from 1st internode from the bottom to the 4th internode from the bottom reaching a significant level. 5) Dry weight of culm of each internode in japonica rice was lower than that of indica rice and dry weight of leaf sheath of each internode in Liangyoupeijiu was significantly higher than that in the other three varieties. Dry weight per unit internode for the second internode from the bottom of japonica rice was slightly higher than indica rice, while the opposite trend was found for the others. 6) Retaining force per hill and buckling resistance of japonica rice were greater than indica rice significantly, while recovery after pushing followed an opposite tendency accordingly. Therefore, japonica rice was provided with strong ability of retaining and lodging, and indica rice had strong recovering ability. Moreover, for japonica rice, high yield and lodging resistance can be achieved at the same time, owing to its small breaking resistance, large bending moment, low plant height, appropriate internode charactericstics, low height of gravity center, enough dry matter of basal internode, and so on.

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Effects of Straw Returning Coupled with N Application on Rice Photosynthetic Characteristics, Nitrogen Uptake and Grain Yield Formation Peng-gang PEI, Jun-hua ZHANG, Lian-feng ZHU, Zhi-hua HU, Qian-yu JIN 2015, 29(3): 282-290.  DOI: 10．3969/j．issn．1001G7216．2015．03．007 Abstract ( )   HTML ( )   PDF (1353KB) ( )   The rice tillering dynamics, photosynthesis variations during late growth stage, dry matter accumulation, nitrogen uptake and rice grain yield were analyzed at various N application levels with straw returning to the field in a fixed field experiment. There were four straw returning treatments and four N application rates in this trial. Straw returning treatments were 0 kg/hm2 (S0),4000 kg/hm2 (S4),6000 kg/hm2 (S6),and 8000 kg/hm2 (S8), respectively. N application rates included 0 kg/hm2 (N0),90 kg/hm2(N90),180 kg/hm2(N180),270 kg/hm2(N270), respectively. The results showed that 1) compared with S0, straw returning without nitrogen application obviously inhibited tiller generation and reduced maximum tillering number at rice early growth stage, while increased dry matter accumulation, nitrogen uptake and flag leaf photosynthetic rate at late growth stage, and increased rice grain yield by 2.22%-4.44%. 2) Without straw returning, tiller number was significantly increased with the rising N application rates, and peak tillering time was 7-14 days earlier than N0. Dry matter accumulation and nitrogen absorption during different rice growth stages and rice grain yield increased with the rising N rates, and photosynthetic rate of rice flag leaf maintained a high level at late growth stage. 3) At the same nitrogen application level, rice tiller generation under S4 and S6 treatments was enhanced comparing with S0. Nitrogen absorption at rice mature stage under S6 treatment was significantly increased by 36.58% compared with S0, and photosynthetic rate of rice flag leaf at late growth stage under S6 treatment were higher than S0, while rice tiller generation, photosynthetic rate of flag leaf and nitrogen absorption under S8 treatment did not show favorable results comparing with S6. 4) Straw returning coupled with nitrogen application significantly affected rice effective panicle number and rice grain yield. To compare with N0,S0, rice grain yield at different nitrogen application levels coupled with straw returning was increased by 9.59%-23.51%, and rice grain yield under N180S6 was up to 10.56 t/hm2. It was concluded that appropriate straw returning amount coupled with appropriate nitrogen application rate enhanced rice tillering and effective panicle formation, increased rice nitrogen uptake and dry matter accumulation, and then increased rice grain yield.

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Evaluation of Chilling Resistance in Yongyou Series of Hybrid Rice at Flowering Stage Yan-hua ZENG, Yu-ping ZHANG, Ya-liang WANG, Jing XIANG, Hui-zhe CHEN, De-feng ZHU 2015, 29(3): 291-298.  DOI: 10．3969/j．issn．1001G7216．2015．03．008 Abstract ( )   HTML ( )   PDF (844KB) ( )   Yongyou series (indica-japonica hybrid rice) and Qianyou 2 (indica hybrid rice), Zhejing 88 (inbred japonica rice) were subjected to low temperature stress (17℃) and normal temperature treatment(25℃) for 4 days and 7 days in phytotron to investigate the grain filling characteristics during flowering stage with the ambient temperature as control. The results showed that seed setting rate and grain yield per panicle of Yongyou series were decreased significantly under low temperature treatment, especially under the 7-day chilling stress. Based on the cold resistance index, Yongyou 538, Zhejing 88, Yongyou 10, Yongyou 6, Yongyou 15 were chilling tolerant lines, Yongyou 8, Yongyou 12, Yongyou 9, Yongyou 17 were chilling sensitive ones, and the others were intermediate type. There was no significant difference in the ratio of indica and japonica background between chilling tolerant lines and chilling sensitive ones. The correlation analysis indicated that under 7-day of chilling stress, the relative cold sensitivity index was significantly correlated with seed setting rate and grain sterility rate at the 0.01 probability level with the correlation coefficients of -0.9552 and 0.9602, respectively.

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Automatic Identification of Rice Light-trapped Pests Based on Images Ding-xiang XIAN, Qing YAO, Bao-jun YANG, Ju LUO, Chang TAN, Chao ZHANG, Yi-cheng XU 2015, 29(3): 299-304.  DOI: 10．3969/j．issn．1001G7216．2015．03．009 Abstract ( )   HTML ( )   PDF (601KB) ( )   Automatic identification and count of rice light-trapped pests is a common and important pest forecasting method in paddy fields. However, most of the light-trapped pests are unnecessary to be monitored and must be removed. This manual method is time-consuming and fatiguing with a low accuracy rate. We developed an automatic method for identifying rice light-trapped pests based on the images. Firstly, we divided the images into several groups according to their morphological features. Each group has three classifications: the back-side image of a pest, the abdomen-side image of this pest, and non-forecasting pest image similar to this pest. Then, thirty-one features including the color, shape and texture features were extracted from each insect image. Finally, three support vector machine classifiers with posterior probabilities were used to train and test the three groups of insects, respectively. In the results, the back-side image and the abdomen-side image of a pest were considered as the same species. We achieved a 97.4% accuracy rate in the three species of rice light-trapped pests.

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Development of Specific DNA Markers for Detecting the Rice Blast Resistance Gene Alleles Pi2/9/zt HUA Lixia1,2,#, WANG Wenjuan1,2,# , CHEN Shen1,2, WANG Congying1,2, ZENG Liexian1,YANG Jianyuan1, ZHU Xiaoyuan1, SU Jing1,2,* 2015, 29(3): 305-310.  DOI: 10.3969/j.issn.1001-7216.2015.03.010 Abstract ( )   HTML ( )   PDF (848KB) ( )   Specific molecular markers for detecting the alleles of Pi2/Pi9/Pizt, designated as Pi2SNP, Pi9SNP and PiztPA, respectively, have been successfully developed through sequence comparison method. These three specific markers can distinctly distinguish target genes from others mapped on Pi2/9 locus, which facilitate the molecular markerassistant selection and the development of pyramiding cultivars combined with other allele R genes. Additionally, 101 main cultivars and breeding parents collected from different riceplanting areas have been diagnosed with these three specific markers, and the results showed that only 2 out of 101 cultivars carried Pizt, but neither Pi2 nor Pi9 band had been detected. So far, it indicated that most of the main cultivars and breeding parents in China do not carry  Pi2/Pi9/Pizt. These results had provided important information for the application of Pi2/Pi9/Pizt in the blast resistance breeding programs.

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Molecular Characterization of T-DNA Integration into Ustilaginoidea virens Mutant B1464 Ya-hui WANG, Yong-feng LIU, Fan LU, Mi-na YU, Lei HUANG, Meng-ting ZHENG, Jun-jie YU, Xiao-le YIN 2015, 29(3): 311-318.  DOI: 10．3969/j．issn．1001G7216．2015．03．01 Abstract ( )   HTML ( )   PDF (1643KB) ( )   With an avirulent Ustilaginoidea virens strain B1464 as material,we analyzed the changes in biological morphology and pathogenic mechanism. Compared to the wild-type U. virens strain P1, the mutant strain B1464 showed no pathogenicity in the field. The rate of growth on MM medium was not different to P1 and B1464. On PSA and TB3 medium the rates of growth were nutritionally endowed. B1464 grew slower and produced few conidiophores in PS medium, and its conidiophores morphology and spore size became smaller. Genomic Southern bolt analysis confirmed that B1464 was single T-DNA insertional events. The flanking sequences of T-DNA obtained by TAIL-PCR were non-adjacent in the wild type. It was founds that the mutant strain lost about 20 kb sequences in the insertion site comparing with the wild type strain. The expression of the flanking genes of the T-DNA was down-regulated, detecting by semi-quantitative RT-PCR. The reason of the chromosome rearrangement and abnormal expression of some genes is the insertion of T-DNA, probably, leading to the mutant strain B1464 lost its pathogenicity.

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Effect of RBSDV Infection on Transcriptional Expression of Abscisic Acid Metabolism Related Genes in Rice Hai-ping NI, Qiu-fang XU, Ying LAN, Qing-qing CHEN, Jin-feng ZHANG, Yi-jun ZHOU 2015, 29(3): 319-326.  DOI: 10．3969/j．issn．1001G7216．2015．03．012 Abstract ( )   HTML ( )   PDF (2672KB) ( )   To investigate the effect of virus infection on abscisic acid (ABA) content in rice, two rice varieties, Nipponbare and Huaidao 5, were inoculated with rice black streaked dwarf virus (RBSDV) artificially via small brown planthoppers, and the ABA content was measured by ELISA method when the plants showed the obvious viral disease symptoms. The results showed that the ABA content was increased in virus infected rice. The ABA content in virus infected Nipponbare was 111.04 ng/g compared to 60.86 ng/g in the control. In Huaidao 5, it was 102.60 ng/g in the virus infected plants and 70.61 ng/g in the control. To reveal how the virus regulates the ABA content, the relative expression levels of genes involved in ABA biosynthesis (OsZEP, OsNCED1, OsNCED2, OsNCED3, OsNCED4 and OsNCED5) and catabolism (OsABA8ox1, OsABA8ox2 and OsABA8ox3) were analyzed in Nipponbare at 8 d, 12 d, 16 d and 60 d after virus infection. The qRT-PCR results showed that the expression levels of the genes involved in ABA biosynthesis and catabolism in the plants than at 8 days after virus infection were higher than those in the control. The expression levels of OsNCED4 and OsNCED5 increased continuously with infection duration. At 60 d, the expression levels of OsNCED3, OsNCED4 and OsNCED5 in RBSDV infected plants were 3.97-, 7.66- and 2.99-fold higher than those in the control, and the expression levels of OsZEP, OsABA8ox1 and OsABA8ox2 were decreased with time extension. The data suggested that RBSDV infection affected the ABA biosynthesis and catabolism metabolism pathway, resulting in the increase of ABA content.

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Genetic Structure of Rice Blast Pathogen Magnaporthe oryzae in Sichuan Province Ling WANG, Shi-min ZUO, Ya-fang ZHANG, Zong-xiang CHEN, Xue-biao PAN, Shi-wen HUANG 2015, 29(3): 327-334.  DOI: 10．3969/j．issn．1001G7216．2015．03．013 Abstract ( )   HTML ( )   PDF (896KB) ( )   Rice blast, caused by Magnaporthe oryzae, is one of the most destructive disease worldwide. The genetic structure of five populations of M. oryzae, collected from Mianyang, Yingshan, Ya’an, Beichuan and Wusheng of Sichuan Province, were analyzed using six fluorescent labeled SSR markers. A total of 43 polymorphic alleles were produced in 124 isolates of M. oryzae. The mean number of observed alleles (Na) and effective alleles (Ne) per locus were 7.2 and 3.1, respectively, and all loci exhibited significant deviations from Hardy-Weinberg equilibrium. The mean observed heterozygosity (Ho = 0.374) was lower than expected (He = 0.502), indicating the deficit of heterozygotes resulting from the accumulation of inbreeding within populations. Analysis of molecular variance showed that the majority (81.17%) of genetic variation was attributed to the differences among isolates within population, with only 18.83% of the variation resulting from differences among populations. High levels of genetic differentiation (Fst, 0.057-0.528) existed among all five geographical populations. Mantel test revealed no significant correlation between the genetic and geographical distances for all populations (r = -0.201, P = 0.587), indicating that the genetic variation of M. oryzae populations was randomly distributed in geographic space. Different levels of gene flow (Nm,0.472 - 4.347), occurred between populations, were also verified by Bayesian-based clustering algorithm analysis by Structure.