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    13 September 2022, Volume 30 Issue 1 Previous Issue   

    Letter
    Review
    Research Paper
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    Letter
    Evaluation of Medicinal Plant Extracts for the Control of Rice Blast Disease
    TAN Yanping, DENG Shiqi, QIN Yonghua, XU Xin, YU You, CUI Liu, WANG Chuntai, JIANG Changjie, LIU Xinqiong
    2023, 30(1): 1. 
    Abstract ( )   PDF (480KB) ( )  

    Rational Design of Grain Size to Improve Rice Yield and Quality

    TAO Yajun, WANG Jun, XU Yang, WANG Fangquan, LI Wenqi, JIANG Yanjie, CHEN Zhihui, FAN Fangjun, ZHU Jianping, LI Xia, YANG Jie
    2023, 30(1): 1. 
    Abstract ( )   PDF (884KB) ( )  
    Panicle Branches Improve Processing Quality of Elite Rice Cultivars
    CHEN Yibo, ZHAO Lei, WANG Chongrong, LI Hong, HUANG Daoqiang, WANG Zhidong, ZHOU Degui, PAN Yangyang, GONG Rong, ZHOU Shaochuan
    2023, 30(1): 5. 
    Abstract ( )   PDF (650KB) ( )  
    Rice panicle branches are key routes for transportation of photosynthetic products to grains. Branch senescence is an important trait that breeders in South China consider when breeding elite rice cultivars. However, little is known about the mechanisms underlying the contributions of stay-green panicle branches to rice yield and quality. Here, we report on stay-green branches that continuously maintained transportation function and provided carbohydrates for basal grain development in the late stages of rice development. This ensured the coordination of development between apical and basal grains, and further improved the processing quality of elite rice. These findings provide strategies for improving the fullness and quality of rice grains and present an important basis for cultivating elite rice.
    Review
    Defensive Role of Plant Hormones in Advancing Abiotic Stress-Resilient Rice Plants
    M. Iqbal R. KHAN, Sarika KUMARI, Faroza NAZIR, Risheek Rahul KHANNA, Ravi GUPTA, Himanshu CHHILLAR
    2023, 30(1): 15. 
    Abstract ( )   PDF (1022KB) ( )  
    Consistent climatic perturbations have increased global environmental concerns, especially the impacts of abiotic stresses on crop productivity. Rice is a C3 staple food crop for the majority of the world’s population. Abiotic stresses, including salt, drought, heat, cold and heavy metals, are potential inhibitors of rice growth and yield. Abiotic stresses elicit various acclimation responses that facilitate in stress mitigation. Plant hormones play an important role in mediating the growth and development of rice plants under optimal and stressful environments by activating a multitude of signaling cascades to elicit the rice plant’s adaptive responses. The current review describes the role of plant hormones-mediated abiotic stress tolerance in rice, potential crosstalk between plant hormones involved in rice abiotic stress tolerance and significant advancements in biotechnological initiatives including genetic engineering approach to provide a step forward in making rice resilient to abiotic stress adversities.
    Research Paper
    Knocking-out OsPDR7 Triggers Up-Regulation of OsZIP9 Expression and Enhances Zn Accumulation in Rice
    MENG Lu, TANG Mingfeng, ZHU Yuxing, TAN Longtao
    2023, 30(1): 25. 
    Abstract ( )   PDF (2450KB) ( )  
    Zinc is an essential trace mineral that is required for plant growth and development. A number of protein transporters, which are involved in Zn uptake, translocation, and distribution, are finely regulated to maintain the Zn homeostasis in plant. In this study, we have functionally characterized an ABC transporter gene, OsPDR7, which is involved in Zn homeostasis. OsPDR7 encodes a plasma membrane-localized protein that is expressed mainly in the exodermis and xylem in the rice root. OsPDR7 mutants resulted in higher Zn accumulation compared with wild-type. Heterogeneous expression of OsPDR7 in a yeast mutant rescued the Zn-deficiency phenotype, implying transport activity of OsPDR7 to Zn in yeast. However, no ZIP genes except for OsZIP9 showed change in expression profile in the ospdr7 mutants suggested that OsPDR7 maintains cellular Zn homeostasis through regulating OsZIP9 expression. RNA-seq analysis further revealed a set of DEGs between the wild-type and ospdr7 mutants that allowed us to propose a possible OsPDR7-associated signaling network involving transporters, hormone responsive genes, and transcription factors. Our results reveal a novel transporter involved in the regulation of Zn homeostasis and will pave the way toward a better understanding of the fine-tuning of gene expression in the network of transporter genes.
    Brassinosteroids Mediate Endogenous Phytohormones Metabolism to Alleviate High Temperature Injury at Panicle Initiation Stage in Rice
    CHEN Yanhua, WANG Yaliang, CHEN Huizhe, XIANG Jing, ZHANG Yikai, WANG Zhigang, ZHU Defeng, ZHANG Yuping
    2023, 30(1): 31. 
    Abstract ( )   PDF (1354KB) ( )  

    High temperatures cause physiological and biochemical changes and significantly affect young panicle development of rice (Oryza sativa L.). Brassinosteroid plays an important role in enhancing crop stress resistance. In this study, we subjected rice cultivars Huanghuazhan (HHZ, heat-resistant) and IR36 (IR36, heat-sensitive) to high temperature (HT, 40 ºC) or normal temperature (NT, 33 ºC) for 7 d at the panicle initiation stage, in conjunction with application of 2,4-epibrassinolide [EBR, a synthetic brassinolide (BR)] or brassinazole (BRZ, a BR biosynthesis inhibitor) at the beginning of the treatments. HT exacerbated spikelet degeneration and inhibited young panicle growth, which was partially prevented by EBR application, while BRZ application aggravated the reduction in spikelet number. HT decreased the contents of BR, active cytokinins (aCTKs), active gibberellins (aGAs) and indole-3-acetic acid (IAA), but increased the content of abscisic acid (ABA) in young panicles. With the change of endogenous hormone levels, physiological and biochemical processes also changed. The activities of key enzymes involved in sucrose hydrolysis, glycolysis and the tricarboxylic acid cycle in young panicles decreased with the change of endogenous hormone levels under HT. In addition, the contents of H2O2 and malondialdehyde (MDA) increased and the activities of antioxidant enzymes decreased in young panicles. Exogenous application of EBR induced the expression of phytohormone biosynthesis-related genes and downregulated the expression of phytohormone catabolism-related genes to increase the contents of endogenous BR, aCTKs, aGAs and ABA, thus promoting the decomposition and utilization of sucrose in young panicles, enhancing the activities of superoxide dismutase, catalase and peroxidase, and reducing the accumulation of H2O2 and MDA in the young panicles, whereas application of BRZ had the opposite physiological effects. These results showed that brassinosteroid mediates endogenous phytohormone metabolism to alleviate HT injury at the panicle initiation stage in rice.

    Differential Expression of Iron Deficiency Responsive Rice Genes in Low Phosphorus and Iron Toxicity Conditions and Association of OsIRO3 with Yield under Acidic Soils
    Ernieca Lyngdoh NONGBRI, Sudip DAS, Karma Landup BHUTIA, Aleimo G. MOMIN, Mayank RAI, Wricha TYAGI
    2023, 30(1): 31. 
    Abstract ( )   PDF (1174KB) ( )  

    With the hypothesis that iron (Fe) deficiency responsive genes may play a role in Fe toxicity conditions as well, we studied five such genes OsNAS1, OsNAS3, OsIRO2, OsIRO3 and OsYSL16 across six contrasting rice genotypes for expression under high Fe and low phosphorus (P) conditions, and sequence polymorphism. Genotypes Sahbhagi Dhan, Chakhao Poirieton and Shasharang are high yielders with no bronzing symptom visible in Fe toxic field conditions and BAM350 and BAM811 are low yielders but do not show bronzing symptoms. Hydroponics screening revealed that the number of crown roots and root length can be traits for consideration for identifying Fe toxicity tolerance in rice genotypes. Fe content in rice roots and shoots of a high yielding genotype KMR3 showing leaf bronzing was significantly high. In response to 24 h high Fe stress, the expression levels of OsNAS3 were up-regulated in all genotypes except KMR3. In response to 48 h high Fe stress, the expression levels of OsNAS1 were 6-fold higher in tolerant Shasharang, whereas in KMR3, it was significantly down-regulated. Even in response to 7 d excess Fe stress, the transcript abundance of OsIRO2 and OsYSL16 was contrasting in genotypes Shasharang and KMR3. This suggested that the reported Fe deficiency genes had a role in Fe toxicity and that in genotype KMR3 under excess Fe stress, there was disruption of metal homeostasis. Under 48 h low P conditions, OsIRO2 and OsYSL16 were significantly up-regulated in Fe tolerant genotype Shasharang and in low P tolerant genotype Chakhao Poirieton, respectively. In silico sequence analysis across 3 024 rice genotypes revealed polymorphism for 4 genes. Sequencing across OsIRO3 and OsNAS3 revealed nucleotide polymorphism between tolerant and susceptible genotypes for Fe toxicity. Non-synonymous single nucleotide polymorphisms and insertion/deletions (InDels) differing in tolerant and susceptible genotypes were identified. A marker targeting 24-bp InDel in OsIRO3, when run on a diverse panel of 43 rice genotypes and a biparental population, was associated with superior performance for yield under lowland acidic field conditions. This study highlights the potential of one of the vital genes involved in Fe homeostasis as a genic target for improving yield in acidic soils.