Phenotypic characters and expression of Cytokinin oxidase 2 (OsCKX2) gene in rice genotypes with enhanced grain filling traits
2021
Mondejar, C,L.C | Diaz, M.G.Q. | Borromeo, T.H. | Laude, T.P. | Dela Cruz, A.A. | Suralta, R.R.
Poor grain filling is still a major problem in rice production. Recent attention in crop varietal improvement is focused on heritable delayed foliar senescence, enhanced root system, and fast-synchronous grain filling pattern. Nine genotypes were characterized for these three enhanced grain-filling traits to determine the role of these traits on grain yield. Based on heritable delayed foliar senescence, NSIC Rc436 and NSIC Rc512 were characterized as Type A, while PSB Rc18 and NSIC Rc514 as Type B. These genotypes had a significantly higher yield than IR64, owing to their high spikelets number. Data suggested a positive correlation between the delayed foliar senescence and grain number. NSIC Rc480, Arabon, Biniding (IR68), NSIC Rc512, Cuevas, and NSIC Rc436 were characterized with phenotypically superior root characters than IR64. A tendency of direct association was observed between the root characters and the percentage of filled grains and 500-grain weight. Only NSIC Rc480 was characterized with a fast-synchronous pattern, and its percentage of filled grains was significantly higher than the other tested genotypes. Integrating these enhanced grain filling traits in the selection criteria may improve poor grain filling in rice, which is a major constraint in improving the rice yield potential. Preliminary work on the expressions of Cytokinin oxidase 2 (OsCKX2), a gene implicated in the regulation of rice grain yield, was likewise conducted. Differences in the OsCKX2 expression was observed, which may entail a positive note on the exploration at the molecular level to identify the possible role of cytokinin in the gene regulation during rice grain filling.
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