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10 March 2018, Volume 32 Issue 2 Previous Issue    Next Issue
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Isolation and Expression Profiles of Cadmium Stress-Responsive Rice WRKY15 Transcription Factor Gene Xixu PENG, Ningning BAI, Haihua WANG 2018, 32(2): 103-110.  DOI: 10.16819/j.1001-7216.2018.7056 Abstract ( )   HTML ( )   PDF (676KB) ( )   【Objective】Cadmium (Cd) is one of the most toxic heavy metal elements to growth and development of plants and human health. WRKY transcription factors play important regulatory roles in the resistance against stresses. But so far, the regulatory functions of WRKY proteins (WRKYs) in the resistant responses to Cd stress in plants remain unclear so far. 【Methods】Full-length coding sequence of OsWRKY15 was amplified by RT-PCR with gene-specific primers designed according to gene prediction. Structural characteristics of OsWRKY15 were analyzed by bioinformatics software; Organ-specific and induced expression patterns of OsWRKY15 were analyzed by qRT-PCR. Transcriptional activation activity of OsWRKY15 was tested by yeast one-hybrid assay.【Results】OsWRKY15, 988 bp in length, contained an entire ORF in length of 825 bp, encoding a protein of 274 amino acid residues consisting of one WRKY domain with a zinc finger motif of C2HC, belonging to the WRKY subgroup III. OsWRKY15 had a nuclear localization signal and was predicted to be localized in nucleus. Yeast one-hybrid assay revealed that OsWRKY15 had transcriptional activation activity. The transcript levels of OsWRKY15 were higher in roots than those in stems and leaves, and the least was in panicles, flowers and dry seeds. Its expression was rapidly and significantly induced in response to Cd exposure, nitric oxide (NO) and abscisic acid (ABA) application with more increase folds in roots than in leaves. However, salicylic acid, jasmonic acid and ethylene exerted no obvious effects on the expression of OsWRKY15. 【Conclusion】OsWRKY15 may be involved in the regulation of rice resistance response to Cd stress through NO- and ABA-dependent signal pathways.

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Cloning and Expression Analysis of RsPhm Gene in Rhizoctonia solani AG-1ⅠA of Rice Sheath Blight Pathogen JIANG Shaofeng, WANG Chenjiaozi, SHU Canwei, ZHOU Erxun* 2018, 32(2): 111-118.  DOI: 10.16819/j.1001-7216.2018.7094 Abstract ( )   HTML ( )   PDF (818KB) ( )   【Objective】In order to elucidate the functions of phenol 2-monooxygenase(RsPhm)gene in melanization of Rhizoctonia solani Kühn AG-1ⅠA, the causal agent of rice sheath blight,【Method】the gene was cloned by routine PCR and RT-PCR techniques, and the bioinformatics analysis of this gene was conducted; furthermore, the relative expression level under catechol stress was determined by using fluorescence quantitative real-time PCR (qRT-PCR) technique. 【Result】Bioinformatics analysis showed that the full-length DNA and cDNA sequences of RsPhm gene were 2 628 bp and 1 983 bp, respectively, which encode 660 amino acids. The phylogenetic tree analysis showed that RsPhm gene had a close relationship in different anastomosis groups (AGs) of R. solani, and a certain evolutionary conservation among different fungal species. Results of qRT-PCR indicated that the exposure to exogenous catechol could improve the expression level of RsPhm gene, and which peaked at 12.5 µg/mL of catechol, with a significant increase of 35.7 times, 19.1 times and 28.4 times up-regulated at 25 µg/mL and 50 g/mL, respectively, but only 2.1 times up-regulated at 100 g/mL.【Conclusion】The full-length sequence of RsPhm gene was obtained, its basic biological information was understood, and its expression pattern under catechol stress was clarified. These findings will lay a basis for the scientific and systematic elucidation of regulatory mechanism of melanin formation by RsPhm gene of R. solani AG-1ⅠA.

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CRISPR/Cas9-mediated Editing of GS3 to Improve Flowering Time in japonica Rice MENG Shuai, XU Peng, ZHANG Yingxin, WANG Hong, CAO Liyong, CHENG Shihua, SHEN Xihong* 2018, 32(2): 119-127.  DOI: 10.16819/j.1001-7216.2018.7112 Abstract ( )   HTML ( )   PDF (943KB) ( )   【Objective】 Flowering time asynchrony is one of the main factors limiting seed production of hybrid rice between male and female parents, and some studies have shown that flowering time is related to grain shape. Loss of function mutant of GS3 was used to study the difference of flowering time in this study so as to elucidate the impact of grain shape on flowering time. 【Method】 CRISPR/Cas9-mediated editing of GS3 to achieve 13 pairs of near-isogenic line japonica varieties. Then the flowering time was investigated with visual methods. 【Result】 T1 individuals derived from T0 generation were genotyped. The sequencing results show that some bases were mutated with single base insertion, including Changbai 25, Jijing 102, Zhejing 88, Wuyunjing 27, J42 and others with bases deletion, including Kenjiandao 6, Kongyu 131, Zhejing 22, Yangjing 4227, Nanjing 9108, J5933, J6167, J5938. For the grain shape of T1, the gs3 mutants conferred longer grain length compared to the wild type, and the gs3 mutants of Jijing 102, Kongyu 131, Zhejing 88, Wuyunjing 27 and Yangjing 4227 were significantly earlier in flowering time than those of the wild type. The others were also earlier, but not significant.【Conclusion】 Long-grain japonica rice has an earlier flowering time than short-grain japonica rice, which could provide references to study the grain-type breeding of japonica rice, and it would accelerate the breeding process of long-grain japonica parents and promote the development of hybrid japonica rice.

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Effects of Exogenous Ethephon on Fertility of Thermo-sensitive Genic Male Sterile Rice Lines Under Low Temperature Inducement LI Linzhi1, WEI Jiaping1, JIA Yanfeng1, LIU Xiaolin1, ZHANG Haiqing2,3, WANG Ming2, MA Hao1,* 2018, 32(2): 128-136.  DOI: 10.16819/j.1001-7216.2018.7045 Abstract ( )   HTML ( )   PDF (797KB) ( )   【Objective】This research aims to elucidate the mechanism behind sterility conversion(infertile convert into fertile) in low temperature of thermo-sensitive genic male sterile rice in seed production in South China by applying exogenous ethephon.【Method】The thermo-sensitive genic male sterile rice cultivars Zhu 1S and Zhun S were treated with artificial cooling water tank (low temperature, 22.5℃) induction for 7 days and sprayed with ethephon (which promote synthesis of ethylene) and the chlorine dioxide solution (inhibitory substances) during fertility-sensitive period. Then the pollen dyeing rate and the bagged seed-setting rate were calculated and the quantitative real-time PCR was conducted. In addition, the promoters of OsACO5 and OsACS5, which are key enzymes of ethylene synthesis pathway, were isolated and analyzed.【Result】Under 22.5℃ for 7 days, the pollen rate of Zhu 1S and Zhun S was 4.3% and 8.9%, and bagged seed-setting rate was 1.6% and 2.5%, respectively. Compared with the water spray control, the pollen rate of lines Zhu 1S and Zhun S was reduced by 3.3 and 7.2 percent, respectively when spraying with 1600 mg/L ethephon. When spraying with 1500 mg/L of chlorine dioxide solution, the pollen rate was increased by 3.5 and 3.3 percent, and the bagged seed setting rate increased by 0.78 and 0.52 percent, respectively. The expression of OsACO5 and OsACS5 in young panicles was significantly increased at 1600 mg/L of ethephon under 22.5℃ induction for 7 days, which were 1.19, 1.24 (Zhu 1S) and 1.24, 1.1 (Zhun S) times of that of the control (water spray) respectively. When sprayed with 1500 mg/L of chlorine dioxide solution for 7 days, the expression of OsACS5 gene in the Zhu 1S and Zhun S was significantly reduced, which were 0.93 and 0.89 times of that of the control (water spray), respectively, but the expression of OsACO5 was not significantly changed. Compared with normal field temperature (control) for 7 days, water spraying, 1600 mg/L of ethephon and 1500 mg/L of chlorine dioxide solution at 22.5℃ down-regulated the expression of OsACO5 and OsACS5 in young panicles of Zhu 1S and Zhun S. The promoters of OsACO5 and OsACS5 contained multiple tissue-specific expression elements and ethylene-regulated cis-acting elements in addition to the basic structures such as TATA-box and CAAT-box. 【Conclusion】Under low temperature condition, spraying 1600 mg/L ethephon in the sensitive period of thermo-sensitive genic male sterile rice had inhibitory effect on fertility conversion from sterility to fertility.

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Development and Verification of a Functional Marker Associated with Resistance to ALS Inhibitor Herbicide CHEN Tao1,2, ZHANG Shanlei1, ZHAO Ling1, ZHANG Yadong1, ZHU Zhen1, ZHAO Qingyong1, ZHOU Lihui1,YAO Shu1, ZHAO Chunfang1, LIANG Wenhua1, WANG Cailin1,* 2018, 32(2): 137-145.  DOI: 10.16819/j.1001-7216.2018.7091 Abstract ( )   HTML ( )   PDF (995KB) ( )   【Objective】 Breeding rice varieties with resistance to ALS-inhibiting herbicide is the most economical and effective method to prevent weeds in direct-sowing field, and molecular marker-assisted selection can improve its efficiency. 【Method】The dominant molecular marker, designed for genotypic detection in different varieties and an F2 population derived from Huaidao 5/Huanghuazhan M-1(mutant with resistance to ALS-inhibiting herbicide) was developed with Tetra-primer ARMS-PCR technique, based on the clarified mutation in CDS of ALS gene. 【Result】 The sequence alignment analysis of ALS gene encoding region showed that only the mutation from T1642G1643 to A1642T1643 leading to the 548th amino acid substitution from tryptophan to methionine in highly conserved region was the critical factors to produce resistance to ALS-inhibiting herbicide in Huanghuazhan M-1, despite the existence of multiple base differences between different indica and japonica rice varieties. The results of PCR detection indicated that three different genotypes could be accurately distinguished by electrophoretic bands, and it was exactly consistent with the phenotype of herbicide resistance at the seedling stage. 【Conclusion】 The genotype associated with two continuous base mutations could be rapidly detected by Tetra-primer ARMS-PCR technique, and the efficiency for varieties with resistance to ALS-inhibiting herbicide could be improved in breeding process.

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Performance of Yield, Photosynthesis and Grain Quality of japonica Rice Cultivars Under Salinity Stress in Micro-plots ZHOU Genyou1, ZHAI Caijiao1, DENG Xianliang2, ZHANG Jiao1, ZHANG Zhenliang1, DAI Qigeng2, *,CUI Shiyou1, * 2018, 32(2): 146-154.  DOI: 10.16819/j.1001-7216.2018.7068 Abstract ( )   HTML ( )   PDF (781KB) ( )   【Objective】Rice growing is one of the widely utilized technologies for desalting, improving and exploiting tidal flat in Jiangsu coastal beach. The objective is to reveal the effects of salinity stress on rice yield, photosynthetic parameters, grain quality and starch viscosity, providing a reference and laying a theoretical basis for developing rice production in Jiangsu coastal beach.【Method】Four japonica rice varieties with better salt tolerance, Tongjing 981, Yandao 12, Yandao 10 and Nanjing 5055 were used to investigate the yield and its components, photosynthetic parameters, rice quality and starch viscosity under salinity stress (S1, 1.112 dS/m for EC1:5) and no salinity stress (S0, 0.207 dS/m, control).【Result】Compared with the control, rice yield decreased significantly under salinity stress, was only 40.5% of that of the control, panicle number per unit area had no significant difference, while grain number per panicle and 1000-grain weight also decreased significantly. The photosynthetic rate and intercellular CO2 concentration decreased significantly, but stomatal induction and transpiration rate had no significant difference between S0 and S1. The processing quality of rice, together with amylose content decreased significantly, the appearance quality almost remained unchanged, while protein content increased significantly. The peak viscosity, trough viscosity, final viscosity, breakdown value, consistence value showed no significant changes, the setback value and pasting temperature increased significantly.【Conclusion】Salinity stress had adverse effects on yield, photosynthetic parameters and grain quality of rice. During the critical period of salt stress on yield and quality, such as booting stage and filling stage, measures should be taken to alleviate salt stress.

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Effects of Irrigation Regimes During Grain Filling Under Different Nitrogen Rates on Inferior Spikelets Grain-Filling and Grain Yield of Rice ZHU Kuanyu1, ZHAN Mingfei1, CHEN Jing1, WANG Zhiqin1, YANG Jianchang1, ZHAO Buhong2,* 2018, 32(2): 155-168.  DOI: 10.16819/j.1001-7216.2018.7060 Abstract ( )   HTML ( )   PDF (1974KB) ( )   【Objective】 To investigate the effects of water and nitrogen application on yield and grain filling, 【Method】 an indica/japonica hybrid Yongyou 2640 with large-panicle and a japonica inbred Huaidao 5 with mid-panicle were grown in pots. After field seedling nursing then transplanting to pots, we designed three N rates, namely 0N (0 g N/pot), medium N level(MN, 2 g N/pot), and high N level(HN, 4 g N/pot), and three irrigation regimes post-anthesis consisting of conventional irrigation (CI, soil water potential was kept at 0 kPa), alternate wetting and moderate drying irrigation (WMD, rewatered when soil water potential reached -15 kPa), and alternate wetting and severe drying irrigation (WSD, rewatered when soil water potential reached -30 kPa). 【Result】 In the CI regime, MN showed the highest grain yield; in the WMD regimes, however, there was no significant difference in grain yield between MN and HN. Furthermore, in the WSD regime, grain yield under HN was the highest. In terms of grain filling, the superior spikelets present no significant difference in grain filling rate and final grain weight compared with all water-nitrogen treatments; Inferior spikelets performs better in grain filling rate and final grain weight at 0N and MN under CI and WMD regimes. However, in the WSD regime, 0N led to the lowest while HN showed the highest grain filling and final grain weight, but not significantly different to MN. The above results showed that there was an obvious interaction between water and nitrogen. Among the varieties, grain filling rate and grain weight of inferior spikelets of indica/japonica hybrid Yongyou 2640 were lower than that of japonica inbred Huaidao 5, and the advantage of grain yield of Yongyou 2640 stemed from higher spikelet number per panicle. Finally, in the WMD+MN treatment, there was a higher nitrogen efficiency, creating higher grain yield with less nitrogen, and achieving the purpose of water and nitrogen saving. Secondly, it also eahanced the activity of root and leaves, improving the non-structural carbohydrate(NSC) remobilization, which promoted the upground biomass development and dry matter translocation in order to strengthen the inferior spikelets filling to induce an increase in grain yield. Therefore, it turns out to be the best water-nitrogen management in this research.

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Effects of Combined Biochemical Inhibitors and Fertilization Models on Rice Population Quality in Yellow Clayey Field ZHOU Xuan1,2,3, JIN Rong4, WU Lianghuan1,2,*, DAI Feng5 2018, 32(2): 169-180.  DOI: 10.16819/j.1001-7216.2018.7041 Abstract ( )   HTML ( )   PDF (1019KB) ( )   【Objective】Application of biochemical inhibitors is one of the effective ways to improve fertilizer use efficiency of rice. The objective of this study is to reveal rice population heterosis as affected by combined inhibitors and fertilization models, and find a suitable high-yield and efficient application method for rice growing region in yellow clayey soil. 【Method】The experiment was conducted to study the interaction effect of biochemical inhibitor combinations and fertilization models (one-off and three-time fertilization) on population quality of rice in yellow clayey field using two factor randomized block design. 【Result】Three-split urea fertilization significantly increased number of productive tillers, effective leaf area index(LAI), dry matter accumulation from heading to maturity, SPAD value at heading stage and grain yield of rice by 0.8%, 24.0%, 9.3%, 1.5% and 14.2% compared with those of one-off fertilization treatment, respectively. On the other hand, addition of biochemical inhibitor (NBPT/NPPT+CP) significantly increased number of productive tillers, panicle setting rate, dry matter accumulation after heading, efficient LAI, and SPAD value at heading stage of rice, and also improved the grain to leaf ratio, enhanced the source-sink relationship among different fertilization models. Correlation analysis showed that dry matter accumulation from heading to maturity was significantly positively related with rice grain yield. Application of new urease inhibitor NPPT alone or combined with CP had the same effect on population quality in paddy field with NBPT. 【Conclusion】The integration and optimization of fertilization technique and combined inhibitors application can improve population quality of rice, photosynthetic product transformation and grain yield in yellow clay field.

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Impacts of Ozone Stress on Dry Matter Accumulation and Distribution of Rice Genotypes with Different Ozone Sensitivity SHAO Zaisheng1, MU Hairong1, ZHAO Yipeng1,2, PENG Bin1, WANG Yulong1, WANG Yunxia3,YANG Lianxin1,* 2018, 32(2): 181-188.  DOI: 10.16819/j.1001-7216.2018.7097 Abstract ( )   HTML ( )   PDF (880KB) ( )   【Objective】The dry matter accumulation and distribution of rice with different ozone sensitivity in response to ozone stress were studied in order to provide reference for ozone-tolerant rice breeding.【Method】Twenty-three rice cultivars or lines were grown in glasshouse-type fumigation chambers with low ozone concentration as control (C-O3, 10 nL/L) and high ozone concentration as elevated O3 treatment (E-O3, 100 nL/L) from a week after transplanting until maturity. The effects of ozone stress on dry matter accumulation and distribution of rice genotypes were determined, as well as the relationships between their responses to ozone stress and the ozone-induced changes in the above-ground biomass at maturity stage. Based on the ozone-induced changes in the above-ground dry weight, these rice genotypes were clustered into three types by the MinSSw (dynamic clustering method-minimum sum of squares within groups) method.【Result】Compared to the control, ozone stress decreased the above-ground dry weight 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. Ozone stress slightly increased the leaf dry weight of rice type A, but significantly decreased that of B (-11%) and C (-25%). Ozone stress significantly decreased stem dry weight by 26%, 41% and 57%, panicle dry weight by 34%, 59% and 62% of rice types A, B and C, respectively. Ozone stress significantly increased the ratio of leaf to above-ground dry weight (+46%), but significantly decreased that of stem (-8%) and panicle (-24%). Ozone level and rice eype interacted with the measured parameters to various degress, which gave rise to small changes in rice type A compared to type B and C.【Conclusion】The above results indicated that, ozone concentration of 100 nL/L seriously inhibited the growth of rice organs, decreased assimilates allocation to stems and panicles, but greatly increased assimilates allocation to leaves, resulted in the decrease of mechanical strength of rice stems. In general, these ozone-induced changes in ozone-sensitive rice genotypes were more obvious than those in ozone-resistant rice types.

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Scanning Electron Microscopic Analysis of Grain Cross-section from Rice with Different Transparency LU Yan1,2, ZHANG Xiaomin2,3, QI Yan2,3, ZHANG Changquan1, LING Yuping3, LIU Qiaoquan1,* 2018, 32(2): 189-199.  DOI: 10.16819/j.1001-7216.2018.7107 Abstract ( )   HTML ( )   PDF (1625KB) ( )   【Objective】 The objective of this study was to set up an ideal method of observation of a single starch granule cross-section, to clarify the relationship between rice transparency and amylose content and to find the structure foundation that caused the poor rice transparency. 【Method】 The pre-treated rice grain cross-section and isolated starch were observed under a scanning electron microscopy.【Result】The transparency of both indica and japonica soft rice with amylose content below 15% was significantly decreased. By comparing different methods of grain cross-section pre-treatments, we found that the direct mechanical fracture method can’t break a single starch granule and the mechanical fracture with glass scraping method could break down an individual starch granule, however, it will cause rough surface and thus difficult to be analyzed quantitatively. As for the liquid nitrogen fracture method, we found it’s an ideal way to break a single starch granule and the cavity in starch granule can be easily observed. We then further analyzed the starch granule arrangement and the internal structure of an individual starch granule in paddy rice from both indica and japonica rice cultivars. We found that all the starch granules arranged tightly and obvious air containing space was observed in an individual starch granule from grains of all dark endosperm rice. Also, we found that the number and area of starch granule cavity in glutinous rice was significantly higher than those in dark endosperm rice. Furthermore, we proved that the number and area of starch granule cavity increased as the grain moisture content decreased.【Conclusion】The direct liquid nitrogen fracture treatment of rice grain cross-section is an ideal method for the single starch granule cross-section observation. Besides, the rice grain transparency showed a close relationship with the moisture content and also the number and size of cavity in the middle of a starch granule but not the starch granule arrangement. Moreover, the size and number of cavities increased as the amylose content decreased.

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Effects of Biochar Amendment to Soil on Life History Traits of Laodelphax striatellus (Hemiptera: Delphacidae) on Rice Plants FU Qiang, LI Baoping, MENG Ling* 2018, 32(2): 200-206.  DOI: 10.16819/j.1001-7216.2018.7113 Abstract ( )   HTML ( )   PDF (954KB) ( )   【Objective】To investigate the potential of biochar application in the control of crop pests, we evaluated the effect of biochar amendment to soil on the small brown rice planthopper (Laodelphax striatellusas) on rice. 【Method】Laboratory experiments were conducted using a 2 × 3 factorial design to explore the effect of the two independent variables (biochar type and application level) on developmental and reproductive performances of the insect on potted rice plants. 【Result】1) Biochar type and application level had an interactive effect on the nymphal duration, which though did not vary with application levels when corn or rice biochar was applied, yet significantly prolonged by 1.54 days when wheat biochar was applied at 30 g/kg compared to 18.70±0.30 d in the control. 2) Biochar type and application level did not have interactive effects on longevity of female adults. Biochar application level did not influence female adult longevity, but corn biochar significantly increased the longevity by 2.13 d compared to 23.70 ± 0.48 d with addition of rice biochar, for wheat biochar, by 3.10 d. 3) There was a biochar type × application level interaction effect on fecundity. Biochar amendment decreased lifetime fecundity of L. striatellus but the effect varied with biochar type and application level. At 30 g/kg biochar level, the fecundity increased for corn biochar by 22.80 and 18.95 eggs compared to those, for rice and wheat biochar respectively. At 50 g/kg biochar level, the fecundity decreased for corn biochar by 16.90 and 21.60 eggs compared to those for rice biochar and wheat biochar.【Conclusion】Biochar amendment to soil can have a negative impact on fecundity of L. striatellus, yet the impact varies with biochar type and application level.