Archive

10 July 2023, Volume 37 Issue 4 Previous Issue    Next Issue
---
Research Papers
Review and Special Topic


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Research Papers

Select

Identification and Gene Mapping of Outcurved Leaf Mutant ocl1 in Rice REN Zhiqi, XUE Kexin, DONG Zheng, LI Xiaoxiang, LI Yongzhao, GUO Yujing, LIU Wenqiang, GUO Liang, SHENG Xinnian, LIU Zhixi, PAN Xiaowu 2023, 37(4): 337-346.  DOI: 10.16819/j.1001-7216.2023.221004 Abstract ( )   HTML ( )   PDF (1775KB) ( )   【Objective】 Moderate leaf rolling can enhance photosynthetic efficiency and improve rice yield. Identification of rice leaf rolling mutants will help elucidate the molecular mechanism behind rice leaf formation. 【Methods】 60Co-γ ray irradiation was used to mutagenize indica rice variety Yuzhenxiang and an outcurved leaf mutant was obtained, tentatively named ocl1 (outcurved leaf 1). The phenotypic and agronomic traits of the mutant were investigated. The F2 population of a cross between ocl1 and 02428 was used for mapping of the OCL1 gene. Additionally, the expression of leaf-rolling related genes was analyzed by quantitative PCR. 【Result】 Compared with the wild-type, the leaves of the mutant was characterized by outcurved and drooping leaves from tillering to mature stage. The yield components including the seed setting rate, 1000-grain weight and yield per plant were obviously decreased in ocl1. Cross-section observation of leaves revealed that the bulliform cells between adjacent vascular bundles of ocl1 were larger than those of the wild-type. Genetic analysis implied that these phenotypes of the mutant were controlled by a pair of recessive nuclear gene. The OCL1 gene was fine-mapped to a 127 kb interval between markers RM19575 and ID02612 on the chromosome 6. Sequencing analysis indicated that one of the genes (LOC_Os06g10600) has a single-base mutation at the intron-exon junction, which leads to abnormal splicing and changes in amino acid sequence. The gene encodes a homologous domain-leucine zipper protein, which is an allele to the leaf rolling related gene ROC8 (URL1). Correspondingly, the expression of ROC5 and LAC17 genes related to bulliform cell development was down-regulated in ocl1, while that of XTH11 was up-regulated in ocl.【Conclusion】 The mutation of OCL1 gene results in outcurved leaf by affecting the development of bulliform cells, which in turn leads to a yield reduction.

Select

Seedling Growth Characteristics of Hybrids Between Transgenic Rice with cry2A*/bar Genes and Weedy Rice XIAO Lequan, LI Lei, DAI Weimin, QIANG Sheng, SONG Xiaoling 2023, 37(4): 347-358.  DOI: 10.16819/j.1001-7216.2023.220612 Abstract ( )   HTML ( )   PDF (1203KB) ( )   【Objectives】 The study aims to evaluate the seedling growth characteristics of hybrids between transgenic rice T2A-1 with cry2A*/bar gene and weedy rice, and lay an experimental basis for evaluating the potential ecological risks of gene flow from T2A-1 to weedy rice. 【Methods】 F1+-F4+ (positive) hybrids (those with transgenic insertion using the transgenic line T2A-1 as the paternal parent), F1− -F4−(negative) hybrids(those using the non-transgenic receptor Minghui 63 (MH63) as the paternal parent) with three weedy rice (WRMM, WRTZ and WRYY) accessions, were used as experimental materials. Under hydroponic culture, germinability was measured. Eight root development indexes were measured and relative root development index under normal nitrogen (40 mg/L) and low nitrogen (20 mg/L), and the seedling growth characteristics of hybrids were evaluated. 【Results】 Transgenic positive hybrids had similar 个germinability to transgenic negative hybrids, but both showed weeker germination potential and germination index compared with the corresponding weedy rice. There were no significant differences in plant height, whole plant dry biomass, and root development between T2A-1 and MH63, and between transgenic positive and transgenic negative hybrids under normal nitrogen conditions. Compared with the weedy rice, hybrids derived from WRMM displayed significantly lower plant height, but similar whole plant dry biomass and the index of root development. Hybrids of WRYY displayed similar seedling growth characteristics with WRYY. While hybrids derived from WRTZ had significantly greater plant height, but significantly lower whole plant dry biomass and index of root development. Under low nitrogen conditions, transgenic positive hybrids had similar or significantly lower plant height, whole plant dry biomass and index of root development than transgene negative hybrids. The relative root development indexes of all hybrids were significantly lower compared with their corresponding weedy rice. 【Conclution】 Compared with their corresponding weedy rice, transgenic positive hybrids displayed equivalent or lower seedling growth momentum under normal nitrogen conditions, but significantly weaker growth under low nitrogen conditions.

Select

Directed Knockout of SD1 Gene Improves Lodging Resistance and Blast Resistance of Rice LI Gang, GAO Qingsong, LI Wei, ZHANG Wenxia, WANG Jian, CHEN Baoshan, WANG Di, GAO Hao, XU Weijun, CHEN Hongqi, JI Jianhui 2023, 37(4): 359-367.  DOI: 10.16819/j.1001-7216.2023.221113 Abstract ( )   HTML ( )   PDF (1390KB) ( )   【Objective】 Huai 119 is a high-yielding japonica rice variety. To improve its unfavorable traits, especially high plant height and poor resistance to rice blast, we used the CRISPR/Cas9 gene editing technology to knock out its ‘Green Revolution’ gene SD1.【Method】 We selected the SD1 gene as the target to construct the CRISPR/Cas9 gene knockout vector, which was then transformed into Huai 119 by Agrobacterium-mediated transformation method, and the homozygous sd1 knockout line without transgenic insertion was obtained. Subsequently, we compared and analyzed the plant height, rice blast resistance, and nitrogen uptake and utilization efficiency of the sd1 and wild-type lines.【Result】 We successfully isolated a homozygous sd1 knockout line without transgenic insertion in the background of Huai 119. In field paddy, it was found that over 60% of the planting area of wild-type Huai 119 was lodging, while the sd1 homozygous mutant population effectively avoided lodging in the later stages of growth due to its shorter plant height. In addition, after treatment with different concentrations of GA (0.01-1.00 μmol/L), the plant height increase of wild-type plants was significantly greater than that of the sd1 line, indicating that the sensitivity of sd1 line to exogenous GA treatment was reduced. The identification of rice blast resistance shows that knocking out SD1 also contributed to the improvement of rice blast resistance of Huai 119. However, the absorption and utilization efficiency of nitrogen decreased due to the knockout of SD1. 【Conclusion】 The knockout of SD1 gene in the rice variety Huai 119 not only improves lodging resistance by reducing plant height, but also enhances the resistance to rice blast.

Select

Effects of High Temperature on Phenylpropane Metabolism and Downstream Branch Metabolic Pathways in Rice Meiosis WANG Shengyong, CHEN Yuhang, CHEN Huili, HUANG Yujie, ZHANG Xiaotian, DING Shuangcheng, WANG Hongwei 2023, 37(4): 368-378.  DOI: 10.16819/j.1001-7216.2023.221112 Abstract ( )   HTML ( )   PDF (532KB) ( )   【Objective】 Our purposes are to investigate how high temperature during rice meiosis affects phenylpropane metabolism and analyze its relationship with heat tolerance of rice. 【Methods】 Eight rice varieties differed in heat tolerance including N22, GLA15 (Guanglu’ai 15), SDWG005, QLY681 (Quanliangyou 681), YLY900 (Y Liangyou 900), YLY1 (Y Liangyou 1), LYP9 (Liangyoupeijiu), and MH101 (Mianhui 101) were used as experimental materials and exposed to room temperature and high temperature for 5 days. The correlations between activities of key enzymes in phenylpropane metabolism and main metabolite contents such as lignin, total flavonoids and total phenols were analyzed as well as the fertility of rice under high temperature stress during the meiotic stage. SDWG005 (heat resistant) and MH101 (heat sensitive) were used as experimental materials to analyze the effects of phenylpropane metabolism, carbohydrate metabolism and antioxidant defense system on heat tolerance of rice. 【Results】 1) Compared with the control, the pollen vitality and fertilization rate of spikelets decreased significantly to various extents at high temperature. 2) HT(high temperature) significantly increased the activities of cinnamate-4-hydroxylase and 4-coumaric acid coenzyme A ligase, as well as the accumulation of lignin, flavonoids and total phenols in spikelets, with resistant varieties registering a higher growth than sensitive ones. 3) Correlation analysis showed that in response to HT pollen activity was significantly correlated with cinnamate-4-hydroxylase activity and lignin content, spikelet fertility was significantly correlated with lignin content, and lignin content was significantly correlated with flavonoid content. 4) Compared with MH101, lignin accumulation in the glumes of SDWG005 was significantly induced under HT. And higher cell wall peroxidase activities were maintained in SDWG005 under HT. 5) Compared with MH101, SDWG005 could maintain higher antioxidant enzyme activities under HT, resulting in less accumulation of H2O2 and malondialdehyde. Under HT, the starch level in SDWG005 flowers was higher, and the expression levels of genes involved in acid invertase, sucrose synthase and ATPase were significantly upregulated. 【Conclusion】 High temperature stress increases the key enzyme activities and metabolite contents in the phenylpropanoid pathway in spikelets during the meiosis stage. The resistant variety accumulates more lignin and flavonoids during HT, has higher antioxidant enzyme activities, higher sucrose metabolism and energy utilization efficiency, thereby improving heat tolerance.

Select

Effects of Exogenous Trehalose on Grain Filling Characteristics and Yield Formation of japonica Rice Cultivar W1844 HUANG Yaru, XU Peng, WANG Lele, HE Yizhe, WANG Hui, KE Jian, HE Haibing, WU Liquan, YOU Cuicui 2023, 37(4): 379-391.  DOI: 10.16819/j.1001-7216.2023.220712 Abstract ( )   HTML ( )   PDF (1450KB) ( )   【Objective】 It is very important to clarify the effect of exogenous trehalose on grain filling and seed setting of large-panicle japonica rice. 【Method】 The effects of different concentrations of trehalose on photosynthetic characteristics, dry matter accumulation and translocation of stems and sheath, grain filling characteristics and yield of large-panicle japonica rice W1844 were investigated by foliar spraying of various concentrations of trehalose (T0, T15, T30, T50, T70 and T100, 0, 15, 30, 50, 70, 100mmol/L, respectively) at the end of booting stage. 【Result】 1) Trehalose exposure increased grain yield, and the highest yield was obtained under T50 treatment. Compared with T0, the yield under T50 treatment increased by 7.71% on average, and the yield and thousand grain weight of superior spikelets increased by 4.36% and 5.92%, respectively, while the yield and thousand grain weight of inferior spikelets increased by 11.98% and 10.01%, respectively. Trehalose had a better effect on the improvement of grain filling and seed-setting of the inferior spikelets. 2) Trehalose treatment changed the grain filling characteristics. Compared with T0, the time to the maximum filling rate of superior and inferior spikelets was shortened by 3.70 and 3.93 d under T50 treatment; the average filling rates of superior and inferior spikelets were increased by 16.57% and 28.03% in the early stage of filling; the average filling rates of superior and inferior spikelets were increased by 20.74% and 24.54% in the middle of grain filling. In addition, compared with T0, the grain weight of superior and inferior spikelets at maximum filling rate increased by 6.74% and 7.36%, respectively. The net photosynthetic rate, stomatal conductance and transpiration rate of rice leaves under T50 treatment increased by 31.08%, 42.58% and 10.42% on average, respectively as compared with T0. 4) Trehalose treatment promoted the accumulation and translocation of non-structural carbohydrates (NSC) in stem and sheath during the heading stage. Compared with T0, the NSC content in stem and sheath at the heading stage increased by 11.63% on average under T50 treatment, and the translocation of dry matter in stems and sheaths increased by 28.52% on average, and the contribution rate to seeds increased by 18.18%. This might be due to the up-regulated expression level of sucrose transporter genes OsSUT2, OsSUT4 and OsSUT5 in stems and sheaths, which promoted dry matter transport in stems and sheaths.【Conclusion】 Exogenous trehalose could effectively improve grain filling and seed setting of large-panicle japonica rice, which might be due to the fact that trehalose treatment could increase the net photosynthetic rate of flag leaf, up-regulate the expression of sucrose transporter genes, and promote the accumulation and translocation of NSC in the stems and sheaths, thus increasing the grain filling rate, seed-setting rate and grain weight of superior and inferior grains. Under the present experimental conditions, 50 mmol/L is the most effective in improving grain filling and seed setting in large-panicle rice W1844.

Select

Effect of Plant-row Spacing on Rice Yield and Root Morphological and Physiological Characteristics in Super High Yield Field DONG Liqiang, YANG Tiexin, LI Rui, SHANG Wenqi, MA Liang, LI Yuedong, SUI Guomin 2023, 37(4): 392-404.  DOI: 10.16819/j.1001-7216.2023.221007 Abstract ( )   HTML ( )   PDF (8622KB) ( )   【Objective】 It is very crucial to investigate the effects of plant-row spacing on rice yield in super-high-yield field and clarify the mechanism behind high yield of rice in high-density mode.【Method】 In 2020 and 2021, Liaojing 419 was grown under five cultivation modes including local farmers' mode (LFM), conventional high-density mode (CHMD), narrow-row high-density mode (NHDM) and two wide and narrow row modes (WNHDM1 and WNHDM2). We measured the root morphological and physiological indexes and the composition factors of rice yield to explore the effects of plant and row spacing on rice yield and root morphological and physiological characteristics in super high-yield fields, clarify the relationship between root distribution and yield composition factors of rice in high-density mode, and reveal the mechanism of high yield of rice in super-high-yield fields in high-density mode.【Result】 Compared with LFM, the productive panicle number under WNHDM1 and WNHDM2 increased by 19.24% and 18.16%, respectively, and grain number per panicle and seed setting rate remained stable. The root indexes of IN(narrow row) area in WNHDM1 and WNHDM2 were not lower than those of other modes, but the difference was greater in OUT(wide row) area, total root length, total root diameter, total root surface area, total root volume and total root dry weight increased by 21.07% and 26.76%, 10.71% and 9.18%, 21.13% and 26.77%, 21.15% and 27.62% and 23.48% and 29.71% in two growing seasons. The root morphological indices in WNHDM1 and WNHDM2 had a positive correlation with panicle number and yield at heading stage and filling stage.【Conclusion】 The high-density mode with optimized plant and row spacing provides rice with asymmetric growth space inside and outside the row, exerts root marginal effect, improves root dry weight, root surface area and root volume, maintains strong root oxidation activity, lays a good basis for the formation of more productive panicles, and achieves the purpose of increasing rice yield.

Select

Effects of Panicle and Bud-promoting Nitrogen Fertilizer Application on Growth of Regenerated Bud and Grain Yield of Ratoon Rice GAO Qianqing, REN Xiaojian, ZHAI Zhongbing, ZHENG Pubing, WU Yuanfen, CUI Kehui 2023, 37(4): 405-414.  DOI: 10.16819/j.1001-7216.2023.221002 Abstract ( )   HTML ( )   PDF (301KB) ( )   【Objective】 This experiment was carried out with the aim to investigate the effects of different nitrogen (N) managements on the growth of regenerated buds, dry matter accumulation and allocation and yield formation of ratoon rice.【Method】 The experiment was conducted in a split-split plot design with three replications. The varieties, Fengliangyouxiang 1(FLYX1) and Liangyou 6326 (LY6326), were designed as main plots, the two panicle nitrogen topdressing rates as sub-plots (N1, 30 kg/hm2 as low level; N2, 60 kg/hm2 as high level), and three nitrogen application rates of bud-promoting fertilizer as sub-sub plots (T1, T2, and T3 were 0, 50 and 100 kg/hm2) under field conditions. The growth of regenerated bud, dry matter accumulation and allocation, aboveground biomass, grain yield and yield components of both varieties were measured.【Result】 The results showed that the high N fertilizer rate had no significant effect on main crop yield of FLYX1, but significantly increased the main crop yield of LY6326, and had no significant effect on ratooning ability and ratoon yield of both varieties. The application of bud-promoting nitrogen fertilizer significantly decreased dry matter translocation of stems and sheaths pre-full heading and harvest index in the main season, and increased dry matter accumulation post-full heading in the ratoon season, resulting in the high grain yield of ratoon rice via increasing the regenerated bud lengths at different nodes, the number of surviving buds and the ratooning ability. Besides, there were interaction effects between panicle nitrogen fertilizer application and bud-promoting nitrogen fertilizer application on ratoon rice yield. The highest annual production of FLYX1 and LY 6326 were 14.46 under the N1T3 treatment and 14.44 t/hm2 under the N2T2 treatment. The regenerated bud length, survival number of buds, and bud growth rate were positively and significantly correlated with the post-full heading dry weight accumulation in the main crop, and negatively and significantly with the translocation of pre-full heading dry weight and harvest index of the main crop; the ratooning ability and ratoon rice yield were positively and significantly correlated with the regenerated bud length, survival number of buds, and bud growth rate.【Conclusion】 High panicle nitrogen fertilizer application rate in the main crop had no significant effect on ratoon yield of both varieties, the application of bud-promoting nitrogen fertilizer enhanced regenerated bud growth, ratooning ability and ratoon yield, and the interaction between panicle and bud-promoting fertilizers significantly affected ratoon yield. Our results showed that bud-promoting fertilizer application increased ratooning ability and ratoon yield mainly via enhancing stem dry matter accumulation in main season and ratoon season, prompting bud growth and panicle formation of ratoon rice. However, more application rate did not further increased ratoon yield. The combination of low panicle nitrogen fertilizer rate and high bud-promoting nitrogen fertilizer and the combination between high panicle nitrogen fertilizer and high bud-promoting nitrogen fertilizer were advantageous to high annual grain yield in FLYX1 and LY6326, respectively. The results suggest that optical application rates of panicle and bud-promoting nitrogen fertilizers is beneficial for high grain yield of ratoon rice.

Select

Effects of Straw Returning Techniques on Soil Nutrients, Organic Carbon and Microbial Diversity in Tobacco-rice Rotation System HUANG Jinwen, LI Rikun, CHEN Zhicheng, ZHANG Bianhong, LEI Han, PAN Ruixin, YANG Mingyu, PAN Meiqing, TANG Lina 2023, 37(4): 415-426.  DOI: 10.16819/j.1001-7216.2023.220901 Abstract ( )   HTML ( )   PDF (1016KB) ( )   【Objective】 It is of great significance to elucidate the effects of different rice-straw returning techniques on soil properties and the underlying mechanisms of rhizosphere microbial remediation and soil improvement, and to find an efficient straw returning technology suitable for the tobacco-rice rotation area in Fujian, so as to lay a basis for high-quality and efficient crop cultivation.【Method】 Using flue-cured tobacco Yunyan 87 and late rice Yongyou 1540 as materials, a 2-year field experiment was carried out to reveal changes in soil nutrient properties and microbial communities in tobacco-rice rotation system and their relationships under various straw returning modes.【Results】 With rice straw returning for two consecutive years, grain yield of each treatment was significantly increased, among which, T2 treatment with lime and urea was the best. The yield of tobacco and rice under T2 treatment increased by 25.67% and 11.49% respectively compared with T0, followed by T3 treatment with Fuganlin and urea, and T1 treatment with straw returning. In the first year, the yield of tobacco in T1 treatment was not significantly different from that of the control, but in the second year, the yields of tobacco and rice were 3.77% and 5.90% higher than those of the control, respectively. After two consecutive years of straw returning, the nutrient and organic carbon contents of topsoil in each treatment were significantly increased, T2 treatment ranked first, followed by T3 treatment. The contents of alkali-hydrolyzed nitrogen, available phosphorus, available potassium, soil organic carbon and dissolved organic carbon in T2 treatment increased by 7.09%, 5.97%, 3.01%, 11.32% and 5.47%, respectively compared with the control. The rhizosphere microbial community analysis showed that the relative abundance of HSB_OF53-F07 related to carbon source metabolism, Arthrobacter related to the degradation of toxic substances and Pseudeurotium related to cellulolysis increased significantly in T2 and T3 treatments compared with the control, while the abundance of Humicola and Penicillium associated with pathogenesis decreased significantly. Further correlation analysis found that the increase of beneficial bacteria in the rhizosphere were positively correlated with soil nutrients, while the abundance of pathogenic bacteria were negatively correlated with soil nutrients.【Conclusion】 Rice-straw returning with lime or Fuganlin and appropriate amount of urea is conducive to increasing the nutrient contents in the topsoil, promoting the growth of beneficial microorganisms such as nitrogen-fixing bacteria, inhibiting pathogenic bacteria, and creating a good soil environment for tobacco-rice rotation, and thus improving crop yield.

Select

Resistance Risk, Cross Resistance and Sublethal Effects of Methoxyfenozide on Rice Stemborers (Chilo suppressalis) LIU Yan, HE Linfeng, WANG Shuchao, YANG Fengxia, GAO Congfen, WU Shunfan 2023, 37(4): 427-435.  DOI: 10.16819/j.1001-7216.2023.220804 Abstract ( )   HTML ( )   PDF (515KB) ( )   【Objective】 We aim to investigate the resistance risk, cross resistance, and sublethal effects of methoxyfenozide on Chilo suppressalis.【Method】 We established the susceptibility baseline of the rice stem borer to methoxyfenozide using rice seedling dipping method and diet incorporation method, respectively. We assessed its resistance risk using diet incorporation method and determined the cross resistance of methoxyfenozide-resistant C. suppressalis population to RH-5849, tebufenozide and fufenozide. Then, we evaluated the effects of sublethal concentration of RH-5849 and methoxyfenozide on the development and reproduction of C. suppressalis using rice seedling dipping method. 【Results】 The results showed that it took 7.7, 6.3, 5.2, 4.4, and 3.5 generations for C. suppressalis to acquire ten-fold resistance to methoxyfenozide when the realized heritability (h2) was 0.402, the slope was 2.451 and the average selective pressure was 50%, 60%, 70%, 80%, and 90%. The bioassay results showed that Yuyao-19 (YY-19) population with a moderate level of resistance to methoxyfenozide (RR=73.4) exhibited moderate cross resistance to fufenozide (RR=24.7) and tebufenozide (RR=26.1), and lower cross-resistance to RH-5849 (RR=2.9). The larval development duration significantly increased but the pupation rate and the pupal weight remarkably decreased after the treatment of sublethal dose of RH-5849 and methoxyfenozide to 2nd instar larvae of C. suppressalis. Moreover, the eclosion rate and the egg laying number per female of F0 and F1 generations decreased significantly after the treatment of sublethal dose of methoxyfenozide. 【Conclusion】 C. suppressalis has a high resistance risk to methoxyfenozide. The field population which exhibits a moderate level of resistance to methoxyfenozide has cross-resistance with other diacylhydrazines. A significant fitness cost is present in rice stem borers treated with a sublethal dose of methoxyfenozide.

Review and Special Topic

Select

Research Progress in the Function of Basic Leucine Zipper (bZIP) Protein Family in Rice HAN Cong, HE Yuchang, WU Lijuan, JIA Lili, WANG Lei, E Zhiguo 2023, 37(4): 436-448.  DOI: 10.16819/j.1001-7216.2023.221018 Abstract ( )   HTML ( )   PDF (1407KB) ( )   As a large family of transcriptional regulators, basic leucine zipper (bZIP) proteins are widespread in eukaryotes. The bZIP proteins characteristically harbor a bZIP domain composed of two closely adjacent structural features: a DNA-binding basic region and the leucine zipper region. Annotations to eighty-nine bZIP transcription factor-encoding genes are available in the japonica rice genome, 45 of which are identified. They are involved in regulating rice growth and development and responses to biotic and abiotic stress, including seed dormancy and germination, floral transition, and photomorphogenesis, and stress and hormone signaling pathway, etc.