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10 November 2015, Volume 29 Issue 6 Previous Issue    Next Issue
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Expression of OsWRKY7 in Rice Ru LI, Jie ZHOU, Dong-yue LI, Xu-ming WANG, Yong YANG, Chu-lang YU, Ye CHENG, Cheng-qi YAN, Jian-ping CHEN 2015, 29(6): 559-570.  DOI: 10.3969/j.issn.1001G7216.2015.06.001 Abstract ( )   HTML ( )   PDF (1714KB) ( )   WRKY proteins are important transcription factors in plants. They are involved in various plant developmental processes, as well as in coping with diverse biotic and abiotic stresses. In this study,we cloned the coding sequence (CDS) and upstream promoter of OsWRKY7 from Nipponbare to analyze its expression patterns. We first analyzed the relative expression level of OsWRKY7 in different tissues by quantitative real-time PCR(qRT-PCR), and the result showed that OsWRKY7 is mainly expressed in leaves, with a higher expression level in flag leaves than that in seedling leaves. We then constructed the pOsWRKY7-GUS expression vector by fusing the putative promoter with GUS reporter gene and transformed the vector into Nipponbare. Subsequent GUS staining showed that OsWRKY7 promoter had activity in primary root tip, leaf blade and glume. Consistent to the qRT-PCR result, massive GUS spots were stained on the entire leaf blade. We also characterized the inducibility of the pOsWRKY7-GUS transgenic plants to pathogen infection and hormone treatment. The results showed that the GUS activities in both leaf and root are up-regulated after inoculation with rice bacterial blight pathogen [Xanthomonas oryzae pv. Oryzae (Xoo)] strain P10, as well as after exogenous application of cytokinin and auxin, while salicylic acid treatment represses GUS activity in both leaf and root. Finally, we fused the CDS of OsWRKY7 with the green fluorescent protein and the GAL4 DNA binding domain, respectively to analyze its subcellular localization in rice and transcriptional activity in yeast. The results showed that OsWRKY7 was localized exclusively to the nucleus of rice stem protoplasts, and has transcriptional self-activation activity in yeast. All these data suggested that OsWRKY7 might act as a transcriptional activator in bacterial blight defense and diverse hormone signal transduction pathways.

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Gene Cloning and Activity Analysis of Adenosine 5'-Phosphosulfate Kinase in Rice De-zhen WANG, Lu-jia LU, Zhao-jun JIANG, Yu-chun RAO, Mei-hao SUN 2015, 29(6): 571-577.  DOI: 10.3969/j.issn.1001G7216.2015.06.002 Abstract ( )   HTML ( )   PDF (1314KB) ( )   Sulfur is an essential element for plant growth. After absorbed from soil by plant roots, sulfate is firstly activated by ATP sulfurylase to form adenosine 5'-phosphosulfate (APS). There are primary and secondary pathways for further conversion of APS, namely reduction of APS by APS reductase to form sulfite, and the phosphorylation of APS by APS kinase (APSK) to form 3'-phosphoadenosine-5'-phosphosulfate (PAPS) as the sulfate donor for the sulfation reactions. Recent researches demonstrated that APSK from Arabidopsis thaliana has an important role in regulating the primary and secondary metabolism of sulfate, and that the formation of intersubunit disulfide bonds between C86 and C119 under oxidation state would decrease its catalytic efficiency dramatically. It had not been reported that whether the rice isozymes were affected by redox environments or not. Sequence analysis demonstrated that two rice APSK (OsAPSK) sequences contain corresponding cysteines homology to Arabidopsis thaliana involved in disulfide formation. In this study, OsAPSK1 and its C36A/C69A mutant were prokaryotically overexpressed, purified and assayed for activity of APS phosphorylation. Activity depression for OsAPSK1 under oxidative stress and no for its mutant C36A/C69A suggested that OsAPSK1 was regulated as proposed previously, and that depression of APSK activity in the secondary pathway would facilitate the primary pathway for sulfate reduction to enhance the cell redox buffering capacity. Further studies such as relations between PAPS contents and oxidative stress, and regulation of different APSK isoenzymes are being investigated.

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Minimum of SSR Markers for Analyzing Genetic Variation of Oryza sativa L. Xiao-ping YUAN, Cai-hong WANG, Hong-zhong DENG, Qun XU, Yue FENG, Han-yong YU, Yi-ping WANG, Xing-hua WEI 2015, 29(6): 578-586.  DOI: 10.3969/j.issn.1001G7216.2015.06.003 Abstract ( )   HTML ( )   PDF (1494KB) ( )   A total of 120 SSR markers were used to determine the minimum of SSR markers for analyzing genetic variation of 69 Oryza sativa L. accessions, which have been clearly classified, based on the genetic diversity and population structure. The results showed that: 1) a total of 1,256 alleles were detected with 120 SSR markers. The number of alleles per locus widely ranged from 2 to 27 with an average of 10.5. Nei's genetic diversity index per locus varied from 0.413 to 0.951 with a mean of 0.760; 2) the minimum of SSR markers for analyzing genetic diversity of rice was 72; 3) the number of SSR markers for analyzing population structure of rice was at least 60.

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Identification and Fine Mapping of a Narrow Leaf Mutant nal10 in Rice Yun-xia FANG, Li ZHU, Jiang-jie PAN, Hai-ping YU, Da-wei XUE, Yu-chun RAO, Xiao-hu WANG, Zhen-yuan SHI, Dong ZHANG, yang-zhou ZHU, Guo-jun DONG, Da-li ZENG, Guang-heng ZHANG, Long-biao GUO, Jiang HU, Qian QIAN 2015, 29(6): 587-594.  DOI: 10.3969/j.issn.1001G7216.2015.06.004 Abstract ( )   HTML ( )   PDF (1719KB) ( )   A novel rice mutant narrow leaf 10 (nal10) was identified from an EMS (ethyl methane sulphonate) mutagenized population of Wuyunjing 7. The mutant was characterized by narrow leaves and smaller architecture phenotype at the seedling stage, and dwarf, narrow leaves, deformed flowers and male sterility at the reproduction stage. Cyto-anatomical analysis indicated that the mutant had fewer large and small veins compared with the wild-type, which may account for the narrow leaf phenotype. The genetic analysis indicated the narrow leaf trait was controlled by a recessive nuclear gene. Using F2 population derived from the cross of nal10 and Taizhongbendi 1, three closely linked SSR markers RM1287, RM562 and RM5638 on chromosome 1 were obtained by the bulked segregant analysis method. With the developed new markers, the gene was finally fine-mapped to an interval of 55.2 kb between the STS markers PK83 and PK78, where a total of eight ORFs were found. RT-PCR analysis indicated the expression levels of auxin biosynthesis, signal transduction and transport related genes were all down-regulated, suggesting NAL10 is a new narrow leaf gene involving in the auxin metabolism. These results laid a foundation for further cloning of the gene and enrich the genetic regulation network of leaf development in rice.

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Gene Mapping of a Narrow and Rolled Leaf Mutant Nrl3(t) in Rice Xiao-hui ZHANG, Ya-zhi QIN, Ying-xin ZHANG, Xiao-deng ZHAN, Zhen-hua ZHANG, Xi-hong SHEN, Shi-hua CHENG, Li-yong CAO, Xian-jun WU 2015, 29(6): 595-600.  DOI: 10.3969/j.issn.1001G7216.2015.06.005 Abstract ( )   HTML ( )   PDF (1125KB) ( )   Nrl3(t) was a novel narrow and rolled leaf mutant from the indica restorer line Zhonghui 8015 after exposure to 60Co-γ ray. Nrl3(t) exhibited significant adaxially-rolled leaves, reduced plant height, shortened panicle length, reduced grain length, grain width and thousand-grain weight, as well as the seed-setting rate. Cytological analysis showed that the rolled leaf phenotype was due to the reduced number of vascular bundleand the changed size of bulliform cells. In an initial mapping with F2 individuals derived from a cross between Nrl3(t) and japonica 02428, the narrow and rolled leaf gene Nrl3(t) was eventually mapped to a 70.3 kb region on the long arm of chromosome 2 between two newly developed sequence tagged site markers C9 and C10E. These results would lay a good foundation for molecular cloning and functional analysis of Nrl3(t).

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Genetic Analysis and Gene Mapping of a Yellow-Green Leaf Mutant djyg in Rice Zhi-qiang LI, Dan ZHU, Zhi-long WANG, Bo DING, Guo-liang WANG 2015, 29(6): 601-609.  DOI: 10.3969/j.issn.1001G7216.2015.06.006 Abstract ( )   HTML ( )   PDF (1427KB) ( )   A spontaneous yellow-green mutant was obtained from the japonica rice cultivar Dongjin in the field, designated as djyg. The mutant showed obvious yellow-green leaf phenotype at the seedling stage but the chlorotic leaves returned to green after the heading stage. Consistent with the phenotype, the chlorophyll b content of the mutant was reduced by 53%, 62% and 36% at the seedling, tillering and heading stages, respectively, compared with that of the wild type (WT). At the tillering stage, we observed that the granas and thylakoid stacks displayed a mess and loose structure, as well as less density in the mutant djyg compared with the WT under a transmission electron microscopy. The transcriptional levels of PORA, Cab1R, PsbA were also decreased in the mutant djyg. Genetic analysis and map-based cloning demonstrated that the phenotype of the mutant was controlled by a major recessive nuclear gene, which is an allele of chlorophyll synthase YGL1. The mutant djyg can be used as a phenotypic marker in rice breeding program since the main agronomic traits of the mutant djyg are normal compared with those of the WT.

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Effect of Foliar Application of Different Zn Compounds on Zn Concentration and Bioavailability in Brown Rice Qing ZHANG, Juan WANG, Li-quan JING, Lian-xin YANG, Yun-xia WANG 2015, 29(6): 610-618.  DOI: 10.3969/j.issn.1001G7216.2015.06.007 Abstract ( )   HTML ( )   PDF (1899KB) ( )   Zinc (Zn) biofortification through foliar Zn application is an attractive strategy to reduce Zn deficiency. Four Zn compounds were applied through foliar spray to three rice varieties at flowering and one week after flowering under field conditions. The concentrations of Zn and phytic acid in brown rice were measured. The results showed that Zn concentration in grains from different parts of a panicle varied significantly, with Zn concentration of grains from upper part of a panicle being higher than that of middle or lower parts. In contrast, phytic acid or the molar ratio of phytic acid to Zn showed the opposite trend. Compared with CK (water spray), foliar application of ZnSO4, Zn-citrate, Zn-gluconate and Zn-EDTA increased Zn concentration by 33%, 31%, 26% and 27%, respectively. The grains at upper or middle parts of a panicle were affected much more than that at lower part. Nipponbare was more sensitive to Zn application than other varieties. Zinc treatment had little effect on the concentration of phytic acid. Averaged across all varieties, the molar ratio of phytic acid to Zn in brown rice was reduced by 25%, 24%, 22% and 18% through foliar application of ZnSO4, Zn-Citrate, Zn-Gluconate and Zn-EDTA, respectively. The reduction was greater in the grains from upper or middle parts than lower part of a panicle. The reduction in Nipponbare or L71 was greater than that in L81. Significant Zn×variety interaction and Zn×variety ×position interaction were detected. In conclusion, foliar Zn application at early grain growing stage significantly increased Zn concentration and bioavailability, and the increment varied with Zn compound, genotype and grain position, with superior spikelets being more susceptible.

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Effects of Rhizosphere Oxygen Concentration on Nutrient Uptake and Root Morphology of Rice at Tillering Stage Chun-mei XU, Tao XIE, Dan-ying WANG, Song CHEN, Cheng-lin JI, Xiu-fu ZHANG, Qing-hua SHI 2015, 29(6): 619-627.  DOI: 10.3969/j.issn.1001G7216.2015.06.008 Abstract ( )   HTML ( )   PDF (674KB) ( )   A hydroponic experiment was conducted to study the effects of rhizosphere oxygen concentration on rice seedling biomass, nutrient absorption and accumulation, and root morphology with Xiushui 09 and Chunyou 84 as material. With an online dissolved oxygen meter, four dissolved oxygen ( DOTs ) levels were set including low oxygen concentration(DOT 0 to 1.0 mg/L), medium oxygen concentration(DOT 2.5 to 3.5 mg/L), high oxygen concentration( DOT >6 mg/L, continuous bubbling with atmospheric air) and control (conventional hydroponics, without oxygen regulation). The results showed that compared with the control, the root, shoot and total dry weights increased by 30.30%, 32.96% and 32.46% for Xiushui 09 and by 7.01%, 1.77% and 9.17% for Chunyou 84, respectively under the medium oxygen concentration; under high oxygen contentration, the root, shoot and total dry weights decreased by 35.35%, 15.62% and 17.76% for Xiushui 09 and by 43.95%, 18.92% and 21.34% for Chunyou 84, respectively. The root to shoot ratios increased under low oxygen treatment. The total absorption and accumulation of N, P, K, Mn, Mg and Ca increased under the medium oxygen treatment, and the total absorption and accumulation of Fe, Cu and Zn increased under the low oxygen treatment. The root tip numbers, length and surface area, the proportion of fine roots also increased and the coarse root decreased under the medium oxygen treatment. Under the medium oxygen treatment, the proportion of fine roots increased, which contributes to nutrient uptake. This might be one of the main reasons for the increase in some element concentrations. The biomass, nutrient concentration, and accumulation, and root morphology obviously varied with cultivar.

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Effects of Nitrogen Application and Mechanical Transplanting Density on Yield Formation and Nitrogen Use Efficiency of Conventional Rice Zhongjiazao 17 Jia-na CHEN, Xiao-bing XIE, Dan-dan WU, Fang-bo CAO, Shuang-lv SHAN, Wei GAO, Zhi-bin LI, Ying-bin ZOU 2015, 29(6): 628-636.  DOI: 10.3969/j.issn.1001G7216.2015.06.009 Abstract ( )   HTML ( )   PDF (1031KB) ( )   ing at the slow development of rice mechanical transplanting in the Yangtze River Valley, we explored the effects of mechanical transplanting densities and nitrogen application on yield formation and nitrogen use efficiency (NRE) in a field experiment with the conventional variety Zhongjiazao17 as material. The results showed that the grain yield didn’t significantly increase with the increasing levels of transplanting density. At the high density (36.4 hill /m2) and high nitrogen rates (175.5 kg/hm2 in early season, 189 kg/hm2 in late season) the grain yield maximized, being 7.84 t/hm2 in early season and 9.10 t/hm2 in late season, while the difference was not significant comparied with high transplanting density plus medium nitrogen rate (110 kg/hm2 in early season, 140 kg/hm2 in late season). Meanwhile, the interaction between the density and N application was not significant. NRE declined as the N application level increased, while it improved as the density increased. N recovery efficiency at the medium N level was 13.26% higher on the average compared with the high N level. And N recovery efficiency at the high density increased by 17.53% compared with the low density. As a result, at high transplanting density and low nitrogen application level, high yield was achieved by increasing effective panicle number per unit area, and N recovery efficienly was improved. It is a key technology for the high-efficiency and high-yielding cultivation of mechanical-transplanted rice in the Yangtze River Valley.

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Action Mechanism by Which SA Alleviates High Temperature-induced Inhibition to Spikelet Differentiation Guan-fu FU, Cai-xia ZHANG, Xue-qin YANG, Yong-jie YANG, Ting-ting CHEN, Xia ZHAO, Wei-meng FU, Bao-hua FENG, Xiu-fu ZHANG, Long-xing TAO, Qian-y JIN 2015, 29(6): 637-647.  DOI: 10.3969/j.issn.1001G7216.2015.06.010 Abstract ( )   HTML ( )   PDF (2147KB) ( )   Heat stress at the spikelet primordium differentiation stage of rice significantly decreases the grain yield due to reduced grain number per panicle. The hybrid rice Yongyou 12 was used as material to investigate the role of salicylic acid(SA) in alleviating the negative effect on spikelet differentiation induced by heat stress. The results indicated that under natural conditions, low concentration of SA increased the spikelet number per panicle, while high concentration decreased the number. Interestingly, either low or high concentrations of SA (10-50000 μmol/L) increased the grain number per panicle under heat stress. The grain yield and grain number per panicle peaked under the treatment of 100 μmol/L SA compared with their respective control (0 μmol/L) under both natural conditions and heat stress. This might attribute to the increase in the leaf photosynthesis rate, antioxidant enzyme activities, concentrations of auxin(IAA) and zeatin(ZR) in spikelets under heat stress. Heat stress occurred at spikelet differentiation stage seemed to cause little damage to the leaf, but the actual light quantum efficiency and net photosynthetic rate of leaf were increased when sprayed with SA. Accordingly, there was no significant difference in the activities of SOD, POD and CAT of leaf in rice. However, these antioxidant enzyme activities in spikelets were significantly decreased when subjected to heat stress, especially under the treatment of 0 μmol/L SA, suggesting that SA could enhance anti-oxidation. Further, SA could also prevent the decrease in the concentrations of IAA and ZR in spikelets induced by heat stress. In sum, SA obviously enhanced heat-resistance in rice at 100-1000 μmol/L.

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Photosynthetic Characteristics and Sucrose Metabolism of Rice Flag Leaf with Different Stomatal Densities Ti-bo SHAN, Wen-jun YAO, Zheng-jin XU, Jin-juan FAN, Jing-lian WU 2015, 29(6): 648-652.  DOI: 10.3969/j.issn.1001G7216.2015.06.011 Abstract ( )   HTML ( )   PDF (388KB) ( )   Three rice lines with different leaf stomatal densities(high, medium and low) were used to study photosynthetic characteristics, sucrose content and the activities of sucrose metabolizing enzymes in flag leaf at full heading stage. The results showed that the content of sucrose and the activity of sucrose phosphate synthase (SPS) in rice flag leaves were extremely significantly and positively correlated with stomatal density, and the activity of sucrose synthase (SS) was significantly positively correlated with stomatal density. Rubisco activity,net photosynthetic rate,sucrose content,SPS and SS in rice leaves with high stomatal density were significantly higher than those in rice leaves with low stomatal density, while negatively correlated with the activity of neutral invertase (NI). These results showed that increased stomatal density improved the photosynthetic efficiency, the sucrose accumulation and the activities of SPS and SS, which contributed to photosynthate(sucrose) transport to grains.

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Construction and Application of Platform for Rice Scientific Data Zhi-guo E, Lei WANG 2015, 29(6): 653-657.  DOI: 10.3969/j.issn.1001G7216.2015.06.012 Abstract ( )   HTML ( )   PDF (574KB) ( )   Chinese National Rice Data Center (http://www.ricedata.cn, CRDC) is an integrated scientific platform for rice research across multiple subjects. Firstly, the database for Chinese rice varieties and their genealogy (DRVG) is established including a fingerprint dataset for widely-grown varieties and a dataset for the excellent germplasm. Moreover, the genealogy tree and the assessment method of backbone parents are developed for DRVG. Secondly, the database for rice functional genes (DRFG) is built, which introduces rice functional genes collected from the references at home and abroad and have two chart generation programs for genetic maps and gene structures through browsers. In addition, the DRFG sets up a dataset of molecular markers for important functional and beneficial genes in breeding. Thirdly, an ontology system is independently produced for knowledge management, and applied to manage the database for DRFG and reference documents. The CRDC platform builts a bridge between biologic data and breeding needs, which is widely used in the domestic and exerts a growing influence.

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Cloning and Expression of the Gene OC-XII Conferring Resistance to Aphelenchoides besseyi in Rice Feng WANG, Qiao-li CHEN, Dan-lei LI, Ya-ming LING, Bo-wen WANG, Rui-zhi ZHANG, Yan-yan JIA, Yong-hang LI, Yu-ying PEI, Xin-ming LU 2015, 29(6): 658-664.  DOI: 10.3969/j.issn.1001G7216.2015.06.013 Abstract ( )   HTML ( )   PDF (1457KB) ( )   The previous resistance verification indicated that Dabaigu (Oryza sativa ssp. indica) resists the infection of Aphelenchoides bessey. To reveal the interaction between the resistance and the pathogenesis-related protein Cystatin, the gene OC-XII was cloned, the docking between OC-XII and A. besseyi Cathepsin B was done, and the expression of OC-XII was tested by quantitative real-time PCR. Results showed that OC-XII bound with Cathepsin B specifily. The expression level of OC-XII was upregulated from 12 hours after infection to 2 days after infection, and downregulated 3 days after infection. These results indicated that OC-XII was involved in the resistance to A. besseyi. The gene has the potential for biological control of plant-parasitic nematodes, and it is necessary to conduct in-depth research.