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10 March 2017, Volume 31 Issue 2 Previous Issue    Next Issue
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Research Progress on Gene Mapping and Cloning for Salt Tolerance and Variety Improvement for Salt Tolerance by Molecular Marker-Assisted Selection in Rice Wen JING, Wenhua ZHANG 2017, 31(2): 111-123.  DOI: 10.16819/j.1001-7216.2017.6083 Abstract ( )   HTML ( )   PDF (23488KB) ( )   Soil salinization severely restricts the development of rice production, and improving salt tolerance in rice has become one of the most important objectives in rice breeding programs. Isolation of novel genes involved in salt tolerance and clarifying its molecular mechanism can lay a foundation for the genetic improvement of salt tolerance in rice. In this paper, we summarized the the progress on mapping of quantitative trait loci (QTL) for rice salt tolerance in the following aspects: mapping populations, growth stages for evaluation of salt tolerance and evaluation methods, evaluation parameters of salt tolerance, QTLs involved in salt tolerance, fine mapping and map-based cloning of QTLs for salt tolerance. We also introduced recent progress on genetic screening and gene cloning of salt-tolerant and salt-sensitive mutants, as well as association mapping of salt tolerance in rice. Additionally, we reviewed the recent advances in variety improvement for salt tolerance by molecular marker-assisted selection in rice.

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Research Advances of Amylopectin Structure in Rice Mingyu FAN, Xiaojing WANG, Xuhong WANG, Liang TANG, Quan XU, Zhengjin XU 2017, 31(2): 124-132.  DOI: 10.16819/j.1001-7216.2017.6051 Abstract ( )   HTML ( )   PDF (8736KB) ( )   Rice is one of the mankind’s major food staples. Given economic development and living standard improving, the quality of rice is becoming an ever more major demand in China. Improving the cooking and eating quality has been the key focus of national and international rice breeding programs. The amylopectin is the main component of rice endosperm and its structure significantly influences the eating and cooking quality of rice. In this review, we summarized the methods of detecting the fine structure of amylopectin and the structure variations of amylopectin between indica and japonica, and concluded the genetic regulation and the synthesis regulation of extra-long chains in amylopectin. The relationships among amylopectin structure, starch physicochemical characteristics and palatabilities were also described. It is necessary to standardize and improve the method of detecting the amylopectin. Investigation on the offsprings derived from the cross between indica and japonica will be an effective way to elucidate the relationship between amylopectin structure and subspecies differentiation. Moreover, the in-depth study on the relationship between eating quality and amylopectin structure will provide theoretical guidance of high-quality rice breeding in China.

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Gene Expression Profile Analysis for Alternate Wetting and Drying Induced Formation of Iron Plaque on Root Surface of Rice Seedlings Youqiang FU, Xiaoli YU, Xujian YANG, Hong SHEN 2017, 31(2): 133-148.  DOI: 10.16819/j.1001-7216.2017.6115 Abstract ( )   HTML ( )   PDF (9961KB) ( )   【Objective】Alternate wetting and drying (AWD) could enhance root activity and resistance to environmental stresses, which is the most important management in rice cultivation. AWD could induce the formation of iron plaque on root surface of rice seedlings significantly. However, differentially expressed genes (DEG) of rice roots remains unknown in the process of AWD induced formation of iron plaque. 【Method】In this study, DEG of rice roots were investigated in response to waterlogging (CK), AWD, CK+Fe, AWD+Fe treatments in sand-culture experiments. 【Results】Compared with CK, AWD induced up-regulated expression of 506 DEG and down-regulated expression of 687 DEG. Compared with CK+Fe, AWD+Fe induced up-regulated expression of 308 DEG and down-regulated expression of 179 DEG. Compared with CK, CK+Fe induced up-regulated expression of 728 DEG and down-regulated expression of 1175 DEG. Compared with AWD, AWD+Fe induced up-regulated expression of 1252 DEG and down-regulated expression of 1189 DEG. Results from Venn diagram analysis indicated that 3822 DEG were involved in the process of AWD-induced formation of iron plaque on root surface. Gene Ontology(GO) analysis showed that a total of 270 DEG participated in the oxidation-reduction process, and 165 DEG were related to the functions of redox enzymes. Kyoto encyclopedia of genes and genomes (KEGG) results indicated that DEG involved in organelle class, signal stimulus, photosynthesis, metabolism and synthesis etc. participated the regulatory process of AWD induced formation of iron plaque on root surface. Thirty eight shared genes showed differential expression in process of both AWD and the formation of iron plaque. The proteins encoded by these genes were responsible for the resistance to disease, drought, redox, translocation and metabolism of rice. In comparison to CK, AWD induced 102 DEG in the process of oxidation and reduction, which accounted for 8.25% of the total. AWD enhanced up-regulated expression of genes that were associated with peroxidase, fatty acid oxidase, glycolic oxidase etc. In comparison to CK, AWD raised root activity and amount of iron plaque on root surface by 22.9% and 45.7%, respectively. Results of real-time RT-PCR confirmed the transcriptional group analysis with the correlation coefficient 0.90. 【Conclusion】 AWD induced expression of many differential genes, enhanced root oxidative capacity, and formed iron plaque on root surface. Peroxidase, fatty acid oxidase and glycolic oxidase might be important genes involved in AWD-induced formation of iron plaque on root surface of rice seedlings.

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Identification and Gene Mapping of a Rolled Leaf Mutant rl(t) in Rice Baolin HAN, Yu TAO, Hongkai ZHANG, Chaojian GU, Yongxiang LIAO, Yongbin PENG, Hongyu ZHANG, Peizhou XU, Xiaoqiong CHEN, Xianjun WU 2017, 31(2): 149-156.  DOI: 10.16819/j.1001-7216.2017.6137 Abstract ( )   HTML ( )   PDF (10829KB) ( )   【Objective】Rice leaf is an important factor for ideal plant architecture in rice, and moderate rolling of the leaves can improve light acceptance and photosynthetic rate. Genetic analysis and primary mapping of the target genes are useful in map-based cloning and function analysis.【Method】A stable inherited mutant, derived from an indica maintainer line Yixiang 1B by EMS treatment, exhibited significantly inward-rolling, more erect and green leaves. At the maturity stage, 10 plants of rl(t) and its wild type(WT) were randomly selected to measure the main agronomic traits including leaf rolling index and leaf erect index. At the tillering stage, the same part of leaf of rl16(t) and WT was taken and fixed by FAA for paraffin sectioning. The chlorophyll content in rl16(t) and WT was tested at the same stage. At the heading stage, the photosynthetic rate, intercellular carbon dioxide concentration, stamatal conductance,and transpiration rate of flag leaves in rl15(t) and WT were measured by using the portable gas exchange system Li-6400.【Result】Compared to wide type, rl(t) displayed reduced plant height, shortened panicle length as well as other agronomic traits. Leaf photosynthetic pigment contents were significantly higher than those of the wild type. However, no difference is observed in photosynthetic efficiency. Cytological analysis showed that the rolled leaf phenotype was possibly caused by the reduced size of bulliform cells. Genetic analysis indicated that rolled leaf phenotype in rl(t) was controlled by a single recessive nuclear gene. In an F2 population derived from a cross between the mutant and Nipponbare, RL(t) was mapped to a 610 kb region between Ind3 and Ind4 on the long arm of chromosome 7. In target region, there are 102 genes altogether.【Conclusion】The rolled leaf of rl(t) was due to increased area of bulliform cells in adaxial layer and no gene related to roll-leaf was reported in the target region. So, RL (t) gene would be a putative novel rolled leaf gene.

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Identification and Gene Cloning of the Brittle Culm Mutant bc1-wu3 in Rice Zuopeng XU, Chongyuan ZHONG, Lijia ZHANG, Qiaoquan LIU 2017, 31(2): 157-165.  DOI: 10.16819/j.1001-7216.2017.6130 Abstract ( )   HTML ( )   PDF (12341KB) ( )   【Objective】Culm strength, an important agronomic trait, is related to lodging resistance of rice. The research of brittle culm mutants and genes has great significance to demonstrate the regulation of genetic mechanism of culm mechanical strength and breed lodging resistance varieties.【Method】In this study, a brittle culm mutant, named bc1-wu3(brittle culm 1 from Wuyujing 3), was obtained from the japonica variety Wuyujing 3 after 60Co-γ induced mutagenesis. F2 population derived from bc1-wu3/Kasalath was used to mapping this corresponding gene by position cloning approach.【Result】The mutant was characterized by the brittle leaf, leaf sheath, and culm during the whole growing stage. Compared with the wild type, the panicle length and grain length of bc1-wu3 decreased significantly, and the grain width presented a significant increase. There was a significant decrease in the cellulose content in culm, the number of sclerenchyma cell layers and the thickness of sclerenchyma cell wall, but the contents of xylose, glucose and arabinose increased significantly in bc1-wu3. Genetic analysis showed that the brittle trait in bc1-wu3 was controlled by one single recessive nuclear gene, and the locus was mapped to a 57 kb genomic region on chromosome 3 between molecular markers M12 and Mk18. In the mapped region the cloned brittle culm gene BC1(LOC_Os03g30250) was included, which might be the candidate gene of bc1-wu3. Sequence analysis revealed that there was a single-base substitution(G-T) in the second exon of BC1 gene in bc1-wu3 mutant, leading to a residue substitution from cysteine to phenylalanine. The data from real-time RT-PCR indicated that there was significant decrease in the expression of BC1 gene in the culm of the mutant. 【Conclusion】Based on these results,we speculate that the bc1-wu3 gene is allelic to BC1 gene. These results would deepen our understanding for the function of BC1and help us to clarify the genetic mechanisms of culm strength.

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Effect of Low Temperature After Flowering on Grain Quality of indica-japonica Hybrid Rice Yanhua ZENG, Yuping ZHANG, Xiaohua PAN, Defeng ZHU, Jing XIANG, Huizhe CHEN, Yikai ZHANG, Yongjun ZENG 2017, 31(2): 166-174.  DOI: 10.16819/j.1001-7216.2017.6073 Abstract ( )   HTML ( )   PDF (2992KB) ( )   【Objective】 The temperature during grain-filling stage of rice is the primary ecologic factor to rice qualities. The research was conducted to reveal the effects of low post-anthesis temperature on rice quality and starch viscosity of Yongyou varieties during grain filling. 【Method】 Four varieties, two indica-japonica hybrid rice (Yongyou538, YY538; Yongyou17,YY17) and two indica rice (Zhongzheyou1, ZZY1) and japonica rice (Zhejing88, ZJ88), were chamber-cultured at temperature as low as 20℃ from 0 to 15 days after flowering(S1), 17℃ from 15 days to 30 days after flowering(S2) and 14 ℃ from 30 days after anthesis to maturity(S3) in a pot experiment. 【Result】 Low temperature after flowering significantly affected the head rice rate, chalkiness, gel consistency, amylose content and protein content of rice, and decreased peak viscosity, hot paste viscosity, cold paste viscosity, breakdown value of Yongyou varieties, and increased setback and consistency. Compared with CK treatment, S1 treatment had the greatest influence on rice processing quality, S2 and S3 treatments had the greatest influence on appearance quality, cooking and eating quality and nutritional quality. Moreover, YY17 is more sensitive to low temperature than YY538. Overall, low temperature after flowering exerted significant impact on grain quality, which varied with genotype, rice quality index and treatment time. 【Conclusion】 The present study indicated that given rice quality indexes differed amony varieties in rice production, we should adopt corresponding measures for high rice quality in grain-filling so as to give the quality potential of indica-japonica hybrid rice into full play.

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A Comparative Study of Ozone-induced Leaf Injury of Rice with Different Ozone Sensitivity Zaisheng SHAO, Hairong MU, Yipeng ZHAO, Yilei JIA, Bin PENG, Lianxin YANG, Yunxia WANG 2017, 31(2): 175-184.  DOI: 10.16819/j.1001-7216.2017.6099 Abstract ( )   HTML ( )   PDF (2008KB) ( )   【Objective】In order to provide reference for ozone-tolerant rice breeding, the leaf characteristics of rice with different ozone sensitivity in response to ozone stress were studied.【Method】By using glasshouse-type fumigation chambers, 23 rice cultivars or lines were grown in soil from around a week after transplanting to maturity at two ozone concentrations: low ozone concentration as control (C-O3, 10 nL/L) and high ozone concentration as elevated O3 treatment (E-O3, 100 nL/L). Based on the decrease in the above-ground biomass under high ozone concentration, these rice genotypes were clustered into three types by the MinSSw (dynamic clustering method-minimum sum of squares within groups) method, namely A, B and C in the order of ozone sensitivity from low to high, respectively. The effects of ozone stress on leaf bronzing score (LBS) and Soil and Plant Analyzer Development (SPAD) values of the top three leaves were examined, and the relationships between leaf LBS or SPAD under ozone stress and the ozone-induced changes in the above-ground biomass at maturity stage were studied.【Result】Ozone stress decreased the above-ground biomass of three rice types A, B and C at maturity by 19%, 39% and 52%, respectively, and significant treatment effects were detected in B and C. The LBS of rice under ozone stress increased along with the process of plant growth, but no significant difference was detected among different types of rice, irrespective of growth stages. Compared to the control, ozone stress significantly decreased the leaf SPAD values of all growth stages, and the decline was increased with the prolonging fumigation time and the lowering leaf position. Averaged across all growth stages, ozone stress significantly decreased the leaf SPAD values of the first, second and third leaf from the top by 11%, 18% and 30%, respectively. On the contrast, the influence of ozone stress on the leaf SPAD values showed no significant difference among different types of rice, and different growth stages showed the same trend. Correlation analysis showed that, although there were positive correlations between the ozone-induced changes in the rice above-ground biomass and LBS of a few growth stages, the ozone-induced changes in the above-ground biomass were not closely associated with that of the leaf SPAD values of all growth stages, and same trends were observed for all leaves at different leaf positions.【Conclusion】The above results indicated that under current experimental conditions, leaf bronzing score and leaf SPAD value were not suitable index to evaluate the rice tolerance to ozone stress.

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Fundamental Features of Source-Sink Characters and Their Regulation in High Nitrogen Efficiency Rice Lines Chen CHEN, Jiaxing ZHANG, Wanyuan LI, Dongnan TANG, Gang LUO, Xiangju WANG, Lanjing MO, Minjia LÜ, Juan ZHOU, Guohua LIANG, Jianye HUANG, Yulong WANG, Youli YAO, Gui-chun DONG 2017, 31(2): 185-194.  DOI: 10.16819/j.1001-7216.2017.6127 Abstract ( )   HTML ( )   PDF (2887KB) ( )   【Objective】In order to reveal the features of the source-sink in N-efficient rice,【Method】we conducted two experiments from 2012 to 2014 in paddy fields. A chromosome single segment substitution lines (CSSSLs) consisted of 114 rice lines were cultured in 2012 and 2013. On the basis of plant nitrogen accumulation per area and yield per area at maturity, the rice cultivars were clustered into six types by MinSSw (Minimum Square Sum Within Groups) method. We selected two lines, one is featured with high nitrogen accumulation and high yield (L68, nitrogen-efficient), the other with low nitrogen accumulation and low yield (L2, nitrogen-inefficient). The effects of nitrogen application levels on yield and source-sink characters were studied. 【Result】1) There was a significant difference among all tested lines in N accumulation per unit area and yield per unit area, the variation of N accumulation per unit area ranged from 11.53 to 27.66 g/m2, the variation of yield per unit area from 311.74 to 763.35 kg/666.7 m2. With the increase of nitrogen accumulation, grain yield tended to increase, but nitrogen accumulation types and the yield types were not completely similar. High nitrogen accumulation is an important basis of high yield, but yield was also affected by other factors; 2) The LAI at heading stage (including valid, efficient and total LAI) and mature stage of the N-efficient rice were higher than that of the N-inefficient. The green leaf weight which is the components of leaf area of N-efficient rice was higher than that of N-inefficient rice, but the specific leaf weight had little difference in different N-efficiency rice. 3) The storage capacity per unit area and spikelet number per unit area of N-efficient rice were higher than those of N-inefficient rice. The storage capacity per unit dry weight, storage capacity per unit leaf area, storage capacity per unit nitrogen absorption of N-efficient rice were large, and their ability of developing storage capacity was strong; 4) The spikelet numbers per unit leaf area, grain yield per unit leaf area and net assimilation rate at seed setting stage of N-efficient rice were large, and their “flux” was fluent and the photosynthetic capability was strong; 5) Comprehensive analysis shows that, the storage capacity had a large influence on the nitrogen efficient absorption, and the increasing storage capacity per unit nitrogen absorption contributed to increase in the storage per unit area. Under different nitrogen application levels, the LAI, storage capacity, N absorption and yield of N-efficient rice were higher than those of N-inefficient rice significantly. Under low nitrogen level, the LAI difference between two different N efficiency rice was maximum, nevertheless the differences of the other three indicators were larger under condition of low and medium nitrogen. 【Conclusion】The source-sink properties of N-efficient rice are better than other types at different N application levels.

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Mouthparts and Antenna and Their Associated Sensilla of Rice and Water-oat Populations of the Striped Rice Borer（Chilo suppressalis） Haiying ZHONG, Juefeng ZHANG, Fang LI, Jianming CHEN 2017, 31(2): 195-206.  DOI: 10.16819/j.1001-7216.2017.6120 Abstract ( )   HTML ( )   PDF (8570KB) ( )   【Objective】In order to explore the ultramorphology in antennae and mouthparts and associated sensilla (especially the types, number and distribution) in different populations of Chilo suppressalis Walker, the two organs and their sensilla at different developmental stages were investigated.【Method】The antennae and mouthparts and associated sensilla of rice and water-oat populations of C. suppressalis were used as materials. We observed the organs with a scanning electron microscopy.【Result】The antennae, mouthparts and their associated sensilla varied with larval stage within populations. The two populations of C. suppressalis possessed the following characters: the pedicel was typically equipped with three sensilla basiconica and two sensilla chaetica; six pairs of sensilla chaetica were found on the labrum; the mandible bore seven incisor cusps distally, and carried two sensilla chaetica basally on its outer face; the cardo and stipes each possessed a sensillum chaeticum distally; three sensilla basiconica, two sensilla chaetica and two sensilla styloconica were observed on the galea; a sensillum digitiformium laterally was found on each maxillary palpus; and sensillum chaeticum were observed on the distal of each labial palpus. Difference in sensillum number of flagellum and maxillary palpus between the two populations were as follows: flagellum of the water-oat population was equipped with a sensillum styloconicum and two sensilla basiconica, while the rice population possessed a sensillum styloconicum and a sensilla basiconica; maxillary palpus of the former was equipped with rive sensilla basiconica and three cylindrical sensilla, whereas four sensilla basiconica and four cylindrical sensilla were carried in the latter. Some sensilla chaetica (located at the pedicel, cardo, stipes), sensilla basiconica (distributed at the pedicel, maxillary palpus and galea), sensilla styloconica (distributed at the flagellum and galea) of water-oat population were significantly longer than those of the rice population; whereas some cylindrical sensilla (located at the maxillary palpus) of 1st- to 5th-instar larvae, and sensilla chaetica (distributed at the galea) of 3rd- to 5th-instar larvae were significantly shorter than those of the rice population.

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Aquatic Insect Populations in Paddy Fields as Affected by Management of Rice Insect Pests Through Ecological Engineering Technology Pingyang ZHU, Xusong ZHENG, Fangcheng ZHANG, Hongxing XU, Xiaoming YAO, Yajun YANG, Guihua CHEN, Zhongxian LÜ 2017, 31(2): 207-215.  DOI: 10.16819/j.1001-7216.2017.6065 Abstract ( )   HTML ( )   PDF (21809KB) ( )   【Objective】With the constant development of the sustainable rice pest management technologies, great progresses are expected to be made in the conservation of aquatic insects in paddy fields by controlling rice insect pests through ecological engineering technology. 【Method】We investigated the effects of the ecological engineering technology on the populations of aquatic insects in rice fields for continuous three years. 【Result】The results showed that the numbers of aquatic predatory damselflies, other predators and neutral insects in ecological engineering rice fields were significantly higher than those in farmer-managed fields, while the numbers of predatory damselflies and neutral insects near the ridges of rice field were significantly higher than those in the middle area of field. 【Conclusion】All results revealed that the ecological engineering technology could promote the breeding of aquatic predators and neutral insects in paddy fields, and could play a positive role in improving the natural control capacity during the later rice stage.

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CRISPR/CAS9-mediated Editing of the Fragrant Gene Badh2 in Rice Gaoneng SHAO, Lihong XIE, Guiai JIAO, Xiangjin WEI, Zhonghua SHENG, Shaoqing TANG, Peisong HU 2017, 31(2): 216-222.  DOI: 10.16819/j.1001-7216.2017.6098 Abstract ( )   HTML ( )   PDF (1203KB) ( )   【Objective】Fragrant rice, which is favored because of its quality characteristics of faint scent and tastiness, is a special rice type. Fragrance in rice is mainly controlled by the gene encoding betaine aldehyde dehydrogenase on chromosome 8.【Method】The fragrant gene Badh2 in Zhonghua 11 was edited by CRISPR/CAS9.【Result】Twenty T1 individuals derived from T0 generation were genotyped. One plant, which contains an additional T base in the first exon of Badh2 without the vector skeleton, was finally produced. qRT-PCR result suggested that Badh2 RNA level was decreased in the mutant. Compared with the wild type, the mutant increased 2-acetyl-1-pyrroline content by the GC-MS method. Furthermore, two rice yield-related traits including tiller numbers and seed-setting rate showed significant difference at the 0.05 level among five traits related to yield and three traits related to cooking and eating quality.【Conclusion】We succeed editing the Badh2 by CRISPR-CAS9 technical in rice, and it would provide abundant theoretical guidance and accelerate the breeding process of fragrant rice.