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28 November 2020, Volume 27 Issue 6 Previous Issue    Next Issue
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Letter

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High-Efficiency Reduction of Rice Amylose Content via CRISPR/Cas9-Mediated Base Editing He Li, Xiufeng Li, Yang Xu, Hualong Liu, Mingliang He, Xiaojie Tian, Zhenyu Wang, Xiuju Wu, Qingyun Bu, Jie Yang 2020, 27(6): 445-448.  DOI: 10.1016/j.rsci.2020.09.001 Abstract ( )   HTML ( )   PDF (474KB) ( )

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Biochemical Responses Associated with Resistance to Nilaparvata lugens (Stål) in Wild Rice Accessions Kaur Sandhu Rajwinder, Singh Sarao Preetinder, Kumari Neelam 2020, 27(6): 449-453.  DOI: 10.1016/j.rsci.2020.09.002 Abstract ( )   HTML ( )   PDF (556KB) ( )

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Progress on Molecular Mechanism of Aluminum Resistance in Rice Jingguang Chen, Qi Lai, Baiquan Zeng, Longbiao Guo, Guoyou Ye 2020, 27(6): 454-467.  DOI: 10.1016/j.rsci.2020.09.003 Abstract ( )   HTML ( )   PDF (963KB) ( )   Aluminum (Al) toxicity in acid soils is a significant limitation to crop production worldwide, as 13% of the world’s rice is produced in acid soil with high Al content. Rice is likely the most Al-resistant cereal and also the cereal, where Al resistance is the most genetically complex with external detoxification and internal tolerance. Many Al-resistance genes in rice have been cloned, including Al resistance transcription factor 1 (ART1) and other transcription factors, organic acid transporter genes, and metal ion transporter gene. This review summarized the recent characterized genes affecting Al tolerance in rice and the interrelationships between Al and other plant nutrients.

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Development of Rice Leaves: How Histocytes Modulate Leaf Polarity Establishment Jiajia Wang, Jing Xu, Qian Qian, Guangheng Zhang 2020, 27(6): 468-479.  DOI: 10.1016/j.rsci.2020.09.004 Abstract ( )   HTML ( )   PDF (749KB) ( )   An ideal leaf shape is beneficial to the yield of rice. Molecular understanding of the leaf primordia and polarity establishment plays a significant role in exploring the genetic regulatory network of leaf morphogenesis. In recent years, researchers have cloned an array of coding genes and a few non-coding small RNAs involved in rice leaf development through regulating the development of leaf primordia, vascular bundles, sclerenchyma cells, bulliform cells, cell walls and epidermis cells. These genes and their interactions play critical roles in rice leaf development through the determination and regulatory role in gene expression, and their coordination with other genetic networks or signal pathways. But the relationship among these genes is poorly defined and the underlying network is still unclear. In this review, we introduced the regulatory pathways of leaf primordium development and leaf polarity establishment, mainly the relationship between cell development mechanism and leaf polarity establishment, focusing on how leaf tissue affects leaf shape. Hopefully, the regulation network reviewed here has immediate implications for future research and genomic design breeding.

Research Paper

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New Allele of HL6 Regulates Trichome Elongation in Rice Fei Shang, Wenbin Mou, Hao Wu, Furong Xu, Chunyan Xiang, Jianfei Wang 2020, 27(6): 480-492.  DOI: 10.1016/j.rsci.2020.09.005 Abstract ( )   HTML ( )   PDF (1409KB) ( )   Trichomes are specialized epidermal cells that play multiple roles in plant development. However, knowledge about the molecular mechanism of trichome development in rice is limited. In this study, a hairy leaf locus HL6 SWWR of rice variety Suwangwanger (SWWR) was identified by map-based cloning. Transgenic complementation and knock-out mutation demonstrated that HL6SWWR regulated trichomes on leaves and expression levels of HL6SWWR affected trichome elongation. Transgenic experiments of PROSWWR:HL6NIP and PRONIP:HL6SWWR indicated that the promoter and coding sequences of HL6SWWR were indispensable for trichome regulation. Sequencing alignment of the promoter and coding regions of HL6 in 22 varieties showed that some cis-binding elements in the promoter region may be related to trichome development, while no decisive variation was found in the coding sequence. Furthermore, RNA-sequencing analysis revealed that 1 415 differential expression genes (DEGs) were detected in hl6SWWR mutant vs wild type and that 1 010 DEGs were found in HL6SWWR complementary transgenic line vs wild type. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that most of the DEGs were involved in metabolite pathway, secondary metabolite biosynthesis, plant pathogen interaction and phytohormone signal transduction in both the two groups. The results indicated that these enhanced pathways are critical during trichome development in rice. Taken together, our results provided new views into the regulatory mechanism of trichome formation in rice.

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Functional Analysis of Phosphate Transporter OsPHT4 Family Members in Rice Ruili Li, Jiaoling Wang, Lei Xu, Meihao Sun, Keke Yi, Hongyu Zhao 2020, 27(6): 493-503.  DOI: 10.1016/j.rsci.2020.09.006 Abstract ( )   HTML ( )   PDF (1446KB) ( )   The transport of phosphate between cytoplasm and subcellular compartments is critical for plant metabolic regulation. We conducted bioinformatic analysis, heterologous expression in yeast, gene expression pattern and subcellular localization analysis to characterize the possible functions of OsPHT4 gene family in rice. Together with the PHT4 genes from higher plants, OsPHT4s can be classified into six distinct groups. OsPHT4;1-OsPHT4;4 are targeted to chloroplasts, and OsPHT4;6-1 and OsPHT4;6-2 are located to Golgi apparatus. OsPHT4 proteins can mediate inorganic phosphate (Pi) transport in yeast. In addition, dynamic transcriptional changes determined by qRT-PCR revealed different expression profiles of OsPHT4 genes in response to phosphate starvation, salicylic acid, abscisic acid and salt stress treatments. These results suggested that OsPHT4 proteins are involved in Pi distribution between the cytoplasm and chloroplast or Golgi apparatus and also involved in stress responses.

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Iksan526 Rice Callus Extract Induces Dedifferentiation of Rabbit Articular Chondrocytes via ERK1/2 and PI-3K/Akt Pathways Eo Seong-Hui, Ja Kim Song 2020, 27(6): 504-514.  DOI: 10.1016/j.rsci.2020.09.007 Abstract ( )   HTML ( )   PDF (1361KB) ( )   The resveratrol-enriched transgenic rice line Iksan526 (IS526), first developed by the Rural Development Administration of Korea using genetic engineering techniques, shows beneficial health effects in mitigating metabolic syndrome and obesity. However, the effects of IS526 on the differentiation of chondrocytes and the underlying mechanism have not been investigated in detail. In this study, the effects and cellular regulatory mechanisms of IS526 on rabbit articular chondrocytes were examined. Following IS526 callus extract treatment, the expression levels of differentiation-related proteins were detected via western blotting, Alcian blue staining and immune-luorescence staining. IS526 decreased the type II collagen and proteoglycan levels in dose- and time-dependent manners. We further analyzed the effects of IS526 on skeleton genesis in zebrafish larvae using Alcian blue staining, which showed a reduction in cartilage formation along with increased production of matrix metalloproteinase (MMP)-13. IS526 also increased the phosphorylation of ERK1/2 and p38 kinase but inhibited the phosphorylation of Akt. Pharmacological inhibition of MMP-13 blocked the IS526-induced decrease in type II collagen levels. Inhibition of p38 kinase or PI-3K/Akt with SB203580 and LY294002 enhanced the suppression of type II collagen, but the blockage of ERK-1/2 by PD98059 rescued IS526-induced dedifferentiation. These results suggested that IS526 regulates type II collagen and MMP-13 expression via the ERK1/2 and PI-3K/Akt pathways in rabbit articular chondrocytes.

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Effects of AG1 and AG2 QTLs on Nonstructural Carbohydrate and Seed Management Options for Rice Seedling Growth and Establishment under Flooding Stress Mondal Satyen, Jamil Hasan M., Ahmed Tofayel, Giashuddin Miah M., C. Sta Cruz Pompe, M. Ismail Abdel 2020, 27(6): 515-528.  DOI: 10.1016/j.rsci.2020.09.008 Abstract ( )   HTML ( )   PDF (1131KB) ( )   Rice (Oryza sativa) plants acquired excess photosynthates in the form of nonstructural carbohydrates (NSCs) in their stems and grain. Despite keen interest in rice NSC, the dynamics of NSC accumulation, translocation and re-accumulation have not yet been well investigated. AG1 and AG2 QTLs associated with flooding tolerance through catalyzing starch into soluble sugar in germinating seeds. Here we conducted three experiments, greenhouse and field to lay the groundwork for large-scale diversity studies on grain NSC and some agronomic traits under direct-seeded rice (DSR) system, using elite lines incorporating AG1, AG2 and AG1-AG2 QTLs into the popular varieties PSB Rc82 and Ciherang-Sub1 along with the donors Kho Hlan On (AG1) and Ma-Zhan Red (AG2). In germinating seedlings, soluble sugars increased, while starch concentration decreased gradually especially in the tolerant checks and AG1-AG2 introgression lines under flooded soil. Soluble sugar accumulation in stem started to increase from the vegetative stage and peaked at the panicle initiation stage then gradually decreased towards the maturity stage. But Sub1-AG lines had higher sugar and starch concentrations at different growth stages than other genotypes in wet season 2016 and dry season 2017. Plant survival rate was positively correlated with the stem NSC at the early vegetative stage (21 days after sowing), and stem NSC was positively associated with plant height at different growth stages. Among the tested seeding rate, the most suitable seeding rate, 4 g/m2 with shallow burial depth (0.5 cm), resulted in better seedling establishment, relatively higher seedling vigor index and higher leaf area index under flooding in DSR system. Introgression of AG1-AG2 QTLs had no any negative impact on nonstructural carbohydrate, germination rate, and growth and biomass production.

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Putative Phosphatase UvPsr1 Is Required for Mycelial Growth, Conidiation, Stress Response and Pathogenicity in Ustilaginonidea virens Meng Xiong, Shuai Meng, Jiehua Qiu, Huanbin Shi, Xiangling Shen, Yanjun Kou 2020, 27(6): 529-536.  DOI: 10.1016/j.rsci.2020.09.009 Abstract ( )   HTML ( )   PDF (1281KB) ( )   Ustilaginoidea virens is the causal agent of rice false smut, which can be a highly destructive disease of rice. The plasma membrane phosphatase Psr1 proteins, which act as a regulator of the salinity stress response in yeast, are widely distributed across fungi, but their functional characterization is sketchy. In this study, we characterized the functions of Psr1 protein, UvPsr1, in U. virens. Analyses of the ∆Uvpsr1 and its complementation strain showed that UvPsr1 is required for normal mycelial growth, conidiation and tolerance to oxidative, osmotic and cell wall stresses. When rice panicles were inoculated with the ∆Uvpsr1 strains, no symptoms of false smut disease developed, showing that UvPSR1 also contributes to the pathogenicity of the fungus. The deletion mutant of UvPSR1 also appeared to produce a smaller titer of toxic compounds able to inhibit elongation of the germinated seeds. In conclusion, our results indicated that UvPsr1 is a new pathogenic factor of U. virens.