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10 May 2024, Volume 38 Issue 3 Previous Issue    Next Issue
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Research Progress in Biological Functions of SPL Family Transcription Factors in Rice HU Li, YANG Fanmin, CHEN Weilan, YUAN Hua 2024, 38(3): 223-232.  DOI: 10.16819/j.1001-7216.2024.230308 Abstract ( )   HTML ( )   PDF (1349KB) ( )   SPL (Squamosa Promoter-binding protein-like) family proteins are plant specific multifunctional transcription factors. There are 19 OsSPL genes in rice, all of which contain a highly conserved SBP domain, which is responsible for binding to the core motif GTAC of the downstream target gene to regulate the target gene expression. The expression of OsSPL is regulated by OsmiR156/529/535 and various factors. Studies have shown that OsSPL plays important roles in many biological processes of rice, including root development, ligule and auricles development, the formation of plant architecture and panicle morphology, grain development and stress response, and is a regulatory hub for rice growth and development. In this review, we summarized the research progress of the OsSPL family in rice, including its phylogenetic evolution, structural characteristics, expression regulation and biological functions, and the research prospects were also discussed.

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Research Progress on the Relationship Between Rice Root, Soil Properties and Methane Emissions in Paddy Fields CHEN Haotian, QIN Yuan, ZHONG Xiaohan, LIN Chenyu, QIN Jinghang, YANG Jianchang, ZHANG Weiyang 2024, 38(3): 233-245.  DOI: 10.16819/j.1001-7216.2024.231206 Abstract ( )   HTML ( )   PDF (1151KB) ( )   The article highlights the critical role of methane (CH4) emissions from rice paddies in contributing to global climate warming and underscores the importance of studying the relationship between rice roots, soil characteristics, and CH4 emissions to mitigate the greenhouse effect. It reviews the mechanisms driving CH4 production and emission in rice paddies, emphasizing the significance of rice roots and soil conditions in influencing these emissions. Additionally, the paper suggests avenues for further research to deepen our understanding of the interplay between rice, soil characteristics, and CH4 emissions from paddy fields. By elucidating these relationships, the study aims to provide a theoretical framework for achieving both high grain yields and carbon sequestration in paddy field ecosystems.

Research Papers

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Overexpression of RGG2, a Heterotrimeric G Protein γ Subunit-Encoding Gene, Improves Drought Tolerance in Rice MIAO Jun, RAN Jinhui, XU Mengbin, BO Liubing, WANG Ping, LIANG Guohua, ZHOU Yong 2024, 38(3): 246-255.  DOI: 10.16819/j.1001-7216.2024.230907 Abstract ( )   HTML ( )   PDF (4213KB) ( )   【Objective】To investigate the role of RGG2, a heterotrimeric G protein γ subunit, in improving drought tolerance in rice.【Methods】The interaction between RGG2 and RGB1 was characterized using the yeast two-hybrid system and split luciferase complementation assays. The expression level of RGG2 and seed germination rates of transgenic lines were examined under exogenous ABA treatment conditions to determine whether RGG2 was involved in ABA response. The role of RGG2 in rice drought tolerance was analyzed by comparing the water loss rates of detached leaves and plant survival rates between wild-type and overexpression lines of RGG2 after drought treatment.【Results】RGG2 physically interacts with RGB1. The expression level of RGG2 was significantly induced by ABA, PEG-6000, and drought treatments. Overexpression lines of RGG2 in the backgrounds of Nipponbare and Wuyunjing 7 exhibited significantly lower seed germination and root length than the wild-type under ABA treatment condition, suggesting that RGG2 positively regulates ABA response. Compared with the wild-type, overexpression lines of RGG2 showed lower water loss of detached leaves and a higher survival ratio under drought treatment. After drought treatment, the expression levels of several ABA- and drought stress-related genes in the overexpression lines of RGG2 were higher than that in the wild-type.【Conclusion】RGG2 positively regulates ABA and drought stress responses, and overexpression of RGG2 improves drought tolerance in rice.

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Signal Peptide Validation and Expression Analysis of Multiple Effectors from Ustilaginoidea virens YIN Xiaoxiao, ZHANG Zhihan, YAN Xiulian, LIAO Rong, YANG Sijia, Beenish HASSAN, GUO Daiming, FAN Jing, ZHAO Zhixue, WANG Wenming 2024, 38(3): 256-265.  DOI: 10.16819/j.1001-7216.2024.231012 Abstract ( )   HTML ( )   PDF (1340KB) ( )   【Objective】Signal peptides are crucial for effector secretion and affect the pathogenic process of pathogenic microorganisms. Previously, ten effector genes were identified to be significantly up-regulated during Ustilaginoidea virens infection in rice spikelets. However, it remains unclear whether these effectors contain functional signal peptides and how they express.【Method】The signal peptides of these effectors were predicted and verified by using SignaIP-5.0 database, Agrobacterium-mediated transient expression in Nicotiana benthamiana, and yeast invertase assay. Besides, the expression patterns of these effectors were analyzed by using RT-qPCR.【Results】All the ten effectors, including UV_44, UV_1548, UV_1567, etc., were predicted to contain a signal peptide. The transient expression method showed that eYFP fusion proteins containing signal peptides were successfully secreted into the extracellular space after plasmolysis in N. benthamiana. Yeast invertase assay showed that the yeast strains harboring signal peptides could grow on the medium with raffinose as the only carbon source with the occurrence of a chromogenic reaction using TTC. All the effector genes had distinct expression patterns, except for UV_6754. Seven of them showed significant up-regulation after inoculation, including UV_44, UV_1567, UV_3667, UV_4213, UV_4989, UV_5215, and UV_8184.【Conclusion】The signal peptides of these effectors had secretory functions, and the effector genes have different expression patterns during U. virens infection. These findings lay a foundation for further research on the functions of the above-mentioned effectors from U. virens.

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QTL Mapping for Tiller Angle in Rice by Genome-wide Association Analysis ZHU Yujing, GUI Jinxin, GONG Chengyun, LUO Xinyang, SHI Jubin, ZHANG Haiqing, HE Jiwai 2024, 38(3): 266-276.  DOI: 10.16819/j.1001-7216.2024.230904 Abstract ( )   HTML ( )   PDF (6018KB) ( )   【Objective】Tiller angle is a critical agronomic trait influencing rice yield. Identifying rice tiller angle QTL (genes) and detecting their elite haplotypes can be beneficial for developing ideal rice varieties. 【Method】333 core germplasms from the rice 3K resources were utilized as research materials. These germplasms were cultivated in Yunyuan and Chunhua of Hunan Agricultural University in 2020 and 2022, respectively. Tiller angles of various germplasms were measured during the heading stage. Genome-wide association analysis was conducted using the MLM model of TASSEL 5.2, combined with the genotypes of the germplasms. 【Results】Six QTL for tiller angle were identified on rice chromosomes 2, 5, 6, 9, and 12, designated as qTA2, qTA5, qTA6.1, qTA6.2, qTA9, and qTA12, respectively. These QTL explained phenotypic variation ranging from 6.23% to 16.22%. Notably, qTA9 co-localized with the major QTL TAC1 for tiller angle, while the other five QTL were newly discovered. Candidate gene analysis was conducted for these five QTL. The candidate genes for qTA2 and qTA6.1 were identified as Os02g0817900 and Os06g0682800, respectively. Os02g0817900 encodes a rice cytochrome P450 family protein, while Os06g0682800 encodes a zinc finger domain protein.【Conclusion】This study successfully identified new QTL for tiller angle in rice and analyzed candidate genes, offering valuable insights for the cloning of tiller angle QTL (genes) and genetic improvement of tiller angle in rice.

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Effects of Drought Priming During Tillering Stage on Panicle Development and Yield Formation Under High Temperature During Panicle Initiation Stage in Rice ZHAO Yiting, XIE Keran, GAO Ti, CUI Kehui 2024, 38(3): 277-289.  DOI: 10.16819/j.1001-7216.2024.231110 Abstract ( )   HTML ( )   PDF (916KB) ( )   【Objective】 The aim of this study was to investigate the impact of drought priming during the tillering stage on rice panicle development and yield formation under high temperatures during the panicle initiation stage, along with the underlying physiological mechanisms.【Method】 Two rice varieties, Liangyoupeijiu (heat-sensitive) and Shanyou 63 (heat-tolerant), were chosen for the study. A pot experiment was conducted with two water treatments (flooding irrigation and drought priming during tillering stage) and two temperature treatments (normal temperature and high temperature during panicle initiation stage). The effects of drought priming on spikelet differentiation and degradation, pollen viability, spikelet fertility, spikelet size, grain yield, and underlying physiological characteristics were evaluated.【Result】 Under normal temperature treatment, there was no significant difference in grain yield between flooding irrigation and drought priming for both varieties. However, under high temperature treatment, drought priming led to a significant increase in seed setting rate and 1000-grain weight, resulting in a 54.0% increase in grain yield for Liangyoupeijiu and a 20.1% increase for Shanyou 63 compared to flooding irrigation. Drought priming also resulted in the significant increases in the activities of peroxidase and superoxide dismutase and significant decrease in malondialdehyde content of spikelet, and significant increase in the pollen viability by 26.0%, and in spikelet fertility by 39.0% in Liangyoupeijiu under high temperature treatment. Under flooding irrigation, high temperature treatment resulted in significant reductions in spikelet size and differentiated spikelet number for both varieties compared to normal temperature treatment. However, under high temperature treatment, drought priming led to significant increases in the contents of panicle non-structural carbohydrates and spikelet cytokinins (trans-zeatin and trans-zeatin-riboside), as well as increases in spikelet length, width, and differentiated spikelet number across both varieties.【Conclusion】 Drought priming during the tillering stage effectively mitigated the negative effects of high temperature stress on spikelet development and fertility by enhancing antioxidant enzyme activities, cytokinin content in spikelets, and non-structural carbohydrate levels in panicles. This resulted in improved rice yield formation under high temperature stress conditions, offering insights for rice production in regions prone to high temperature stress.

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Mechanism of Hydrogen Sulfide, a Signaling Molecule Involved in Reducing the Inhibitory Effect of Aluminum Toxicity on Rice Growth Together with Sulfur Fertilizer WEI Qianqian, WANG Yulei, KONG Haimin, XU Qingshan, YAN Yulian, PAN Lin, CHI Chunxin, KONG Yali, TIAN Wenhao, ZHU Lianfeng, CAO Xiaochuang, ZHANG Junhua, ZHU Chunqun 2024, 38(3): 290-302.  DOI: 10.16819/j.1001-7216.2024.230910 Abstract ( )   HTML ( )   PDF (2391KB) ( )   【Objectives】The objective of this study was to explore the cultivation method and internal mechanism of alleviating aluminum (Al) toxicity in acidic soil by increasing hydrogen sulfide (H2S) production in rice through sulfur fertilizer application. 【Methods】With the Al-sensitive rice cultivar kasalath as material, six pot experiment treatments were employed: CK (control), CK+S (sulfur fertilizer application), CK+NaHS (H2S donor), Al (aluminum treatment), Al+S, and Al+NaHS. The study measured rice internal H2S content, Al content, antioxidant system enzyme activities at different growth stages, and the indexes related to root growth and photosynthesis during the tillering stage to explore the mechanism of sulfur fertilizer in alleviating the inhibitory effect of Al toxicity on rice growth via an H2S-dependent pathway. 【Results】Compared to the Al treatment, the Al+S treatment significantly increased the H2S content in rice. Specifically, it increased by 19.27% and 34.99% at the tillering and full heading stages in rice leaves, and by 39.72%, 21.08%, and 30.73% at the tillering, full heading, and mature stages in rice roots. Additionally, the Al+S treatment significantly enhanced rice root growth and photosynthesis ability at the tillering stage, while decreasing Al content in rice root, shoot, and leaves at different stages. Specifically, it decreased by 40.98%, 28.47%, and 24.18% at the tillering stage, by 14.58%, 50.30%, and 13.17% at the full heading stage, and by 14.44%, 29.78%, and 8.70% at the mature period. Further studies showed that the Al+S treatment significantly enhanced the activity of antioxidant enzymes (SOD, CAT, APX, POD), reduced the content of hydrogen peroxide (H2O2), malondialdehyde (MDA), and superoxide anion (O2−·) content in rice, increased the relative expression levels of OsALS1 (related to cytoplasmic Al compartmentalization in vacuoles), and increased the relative expression levels of OsSTAR1 and OsSTAR2 (related to cell wall repair damaged by Al). Additionally, the treatment of Al+NaHS displayed similar effects. 【Conclusions】 The application of exogenous sulfur fertilizer increased internal H2S content, alleviating the inhibition to rice root growth and photosynthesis induced by Al toxicity. It also increased antioxidant activity, thereby reducing peroxidation damage induced by Al toxicity and decreasing Al content. Furthermore, exogenous sulfur fertilizer application facilitated cytoplasmic Al compartmentalization in vacuoles, reduced cell wall Al deposition, and altered Al form in the rice rhizosphere, thus reducing Al uptake in rice and mitigating growth inhibition induced by Al toxicity.

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Effects of Planting Patterns on Starch Content and Activities of Key Starch Enzymes in Rice Grains ZHOU Tian, WU Shaohua, KANG Jianhong, WU Hongliang, YANG Shenglong, WANG Xingqiang, LI Yu, HUANG Yufeng 2024, 38(3): 303-315.  DOI: 10.16819/j.1001-7216.2024.230908 Abstract ( )   HTML ( )   PDF (2134KB) ( )   【Objective】 The objective of this study was to investigate the effects of different planting methods on starch formation and key enzyme activities in rice grains, aiming to provide insights for improving direct seeding techniques for rice cultivation in Ningxia Hui Autonomous Region.【Methods】 The experiment was conducted at the original seed farm of Ningxia Hui Autonomous Region from 2020 to 2021. Fuyuan 4 (FY4), Ningjing 28 (NJ28), Ningjing 43 (NJ43), and Ningjing 50 (NJ50) were selected as experimental materials. Soil moisture conservation, dry direct seeding (Z1), watering after sowing (Z2), and transplanting (Z3) were chosen as planting methods. A split-zone design was employed to study the effects of planting methods on rice yield, starch content, and key enzyme activities.【Results】 Under different planting methods, direct-seeded rice exhibited higher amylose content and total starch content, while transplanted rice showed higher amylopectin content. The total starch content followed the order: Z2 > Z1 > Z3, while the amylopectin content followed the order: Z3 > Z2 > Z1. In 2021, the highest amylose content of NJ28 under Z1 planting mode was 21.90%, while the highest amylopectin content of NJ28 under Z3 planting mode was 51.64%. Starch synthesis and accumulation in grains are primarily influenced by the activity of key enzymes in starch synthesis. Compared to Z3, Z1 and Z2 significantly reduced the activities of AGP and GBSS. Transplanting notably increased UGP and SBE activities of FY4 and NJ43, while direct seeding increased UGP and SBE activities of NJ28 and NJ50. Additionally, under different planting methods, Z1 significantly increased the activity of SSS enzyme. Under Z3 planting mode, the maximum AGP activity of NJ43 was 28.53 U·g-1·min-1, which was 4.1% and 8.4% higher than that of Z2 and Z1, the maximum GBSS activity of NJ28 was 10.36 U·g-1·min-1, which was 11.2% and 13.5% higher than that of Z2 and Z1 treatment respectively. Similarly, under Z1 planting mode, the maximum SSS activity of NJ50 was 20.05 U·g-1·min-1. Moreover, compared to transplanted rice, the 1000-grain weight and seed setting rate of directly seeded rice were significantly higher, although the panicle length and grain number were lower. Consequently, the yield of transplanted rice was significantly higher than that of directly seeded rice. In 2020, the yield of NJ50 under Z3 planting mode reached 898 kg/666.7 m2, which was 30.7% and 39.4% higher than that of Z1 and Z2, respectively.【Conclusion】 The findings indicate that while the yield of rice under direct seeding was lower compared to transplanting, the 1000-grain weight and seed setting rate were significantly increased by direct seeding. Additionally, direct seeding led to higher activity of key enzymes involved in starch formation and increased amylose content in rice grains, consequently enhancing the total starch content in rice grains.

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Relationships Between Texture Profiles of Rice Noodles and Physicochemical Characteristics of Rice Grains XIAO Zhengwu, FANG Shengliang, CAO Wei, HU Liqin, LI Xing, XIE Jiaxin, LIAO Chengjing, KANG Yuling, HU Yuping, ZHANG Keqian, CAO Fangbo, CHEN Jiana, HUANG Min 2024, 38(3): 316-323.  DOI: 10.16819/j.1001-7216.2024.231108 Abstract ( )   HTML ( )   PDF (2525KB) ( )   【Objective】The objective of this study was to investigate the key physicochemical characteristics that determine the texture profiles of rice noodles from different noodle rice cultivars. This research aims to lay a theoretical basis for the breeding of high-quality noodle rice cultivars.【Methods】Field experiments were conducted with five noodle rice cultivars (Guanglu’ai 4, Zhongjiazao 17, Xiangzaoxian 24, Zhongzao 39, Zhuliangyou 729) in Liuyang, Hunan Province, during both the early and late seasons from 2020 to 2022.【Results】Significant differences in texture profiles were observed among noodle rice grown in different years and seasons (P < 0.01). The hardness, springiness, chewiness, cohesiveness, and resilience of rice noodles ranged from 1651 to 4083 g, 0.860 to 0.922, 1295 to 2685 g, 0.760 to 0.858, and 0.532 to 0.633, respectively. Correlation analysis indicated that the hardness and chewiness of rice noodles showed no significant correlation with the physicochemical characteristics of rice (P > 0.05). However, the springiness of rice noodles was positively correlated with the total starch and amylose content (P < 0.01) and negatively correlated with the setback viscosity (P < 0.05).【Conclusion】Suitable climatic conditions exist for growing noodle rice. The total starch content, amylose content, and setback viscosity were identified as critical factors affecting the texture profiles of rice noodles. Increasing the total starch and amylose content while decreasing setback viscosity can lead to improved springiness in rice noodles.

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An Empirical Study on The Factors Influencing the Development of Rice Production Outsourcing in China: From the Perspective of Population Effect GUAN Yaqi, E Zhiguo, WANG Lei, SHEN Hongfang 2024, 38(3): 324-334.  DOI: 10.16819/j.1001-7216.2024.231007 Abstract ( )   HTML ( )   PDF (1337KB) ( )   【Objective】 This paper explores the factors influencing the development of rice production outsourcing from a population perspective, aiming to provide insights for the selection of pathways and the advancement of moderate-scale management in rice production outsourcing and agriculture in China.【Method】 Using cross-sectional data gathered from 631 farmers and 92 villages surveyed across four major rice-producing provinces nationwide in 2019, a binary logistic model was employed to empirically analyze the factors impacting rice production outsourcing.【Result】 1) The individual effect on agricultural outsourcing was found to diminish, while the group effect emerged. 2) Groups played a pivotal role in fostering rice production outsourcing through neighborhood, learning, and environmental effects:a. The expansion of neighborhood management scale facilitated the development of labor-intensive links. b. The income level within neighborhoods exhibited no significant promotion effect on the outsourcing of labor-intensive links. c. The learning effect positively influenced the development of both technology-intensive and labor-intensive sectors. d. The organizational environment provided space for the further advancement of labor-intensive and technology-intensive sectors. e. The supply environment of agricultural materials positively contributed to the development of labor-intensive outsourcing.【Revelation】 Enhancing the influence of village groups, leveraging the leading role of the neighborhood model, providing robust vocational skills training and guidance for the agricultural labor force, strengthening the organizational environment of villages, and establishing specialized and socialized agricultural cooperative organizations are recommended strategies.