Panda Binay B, Badoghar Alok K, Sekhar Sudhanshu, Kariali Ekamber, Mohapatra Pravat K, Shaw Birendra P
Environmental Biotechnology Laboratory, Institute of Life Sciences, Nalco Square, Bhubaneswar-751023, Odisha, India.
School of Life Sciences, Sambalpur University, Sambalpur, 768019, Odisha, India.
Funct Plant Biol. 2016 Mar;43(3):266-277. doi: 10.1071/FP15229.
Despite the prevalence of poor grain filling in rice (Oryza sativa L.) under abiotic stress, the reason for this is largely unexplored. Application of 0.75% NaCl to a salt-sensitive rice cultivar at late booting resulted in a >20% yield loss. Spikelets per panicle and the percentage of filled grain decreased significantly in response to NaCl application. The inhibitory effect of NaCl on grain filling was greater in basal than in apical spikelets. Sucrose synthase (SUS) activity was positively correlated with grain weight. The transcript levels of the SUS isoforms differed greatly: the levels of SUS2 increased significantly in response to salt; those of SUS4 decreased drastically. Gene expression studies of starch synthase and ADP-glucose pyrophosphorylase showed that the decreased transcript levels of one isoform was compensated by an increase in those of the other. Salt application also significantly increased the gene expression of the ethylene receptors and the ethylene signalling proteins. The increase in their transcript levels was comparatively greater in basal than in apical spikelets. Significant enhancement in the transcript levels of the ethylene receptors and the increase in the production of ethylene indicated that the salt-induced inhibition of grain filling might be mediated by ethylene. Additionally, the inhibition of chromosomal endoreduplication mediated by decreased transcript levels of B-type cyclin could explain poor grain filling under salt stress. A significant increase in the transcript levels of the ethylene-responsive factors in the spikelets during grain filling in response to salt indicated their possible protective role in grain filling under stress.
尽管在非生物胁迫下水稻（Oryza sativa L.）籽粒充实不良的情况普遍存在，但其原因在很大程度上仍未得到探索。在孕穗后期对一个盐敏感水稻品种施用0.75%的NaCl导致产量损失超过20%。每穗小穗数和结实粒百分比因施用NaCl而显著降低。NaCl对籽粒充实的抑制作用在基部小穗中比在顶部小穗中更大。蔗糖合酶（SUS）活性与粒重呈正相关。SUS同工型的转录水平差异很大：SUS2的水平因盐处理而显著增加；SUS4的水平则急剧下降。淀粉合酶和ADP - 葡萄糖焦磷酸化酶的基因表达研究表明，一种同工型转录水平的降低被另一种同工型转录水平的增加所补偿。施用盐还显著增加了乙烯受体和乙烯信号蛋白的基因表达。它们转录水平的增加在基部小穗中比在顶部小穗中相对更大。乙烯受体转录水平的显著提高和乙烯产量的增加表明，盐诱导的籽粒充实抑制可能由乙烯介导。此外，B型细胞周期蛋白转录水平降低介导的染色体核内复制抑制可以解释盐胁迫下籽粒充实不良的现象。在籽粒充实期间，盐胁迫导致小穗中乙烯响应因子的转录水平显著增加，表明它们在胁迫下的籽粒充实中可能具有保护作用。
