Identification of Novel QTLs for Spikelet Fertility, Panicle Compactness and Phytohormone Ethylene to Decipher Poor Grain Filling of Basal Spikelets in Dense Panicle Rice

Abstract

High grain number is positively correlated with grain yield in rice, but it is compromised because of poor filling of basal spikelets in dense panicle bearing numerous spikelets. The phenomenon that turns the basal spikelets of compact panicle sterile in rice is largely unknown. In order to understand the factor(s) that possibly determines such spikelet sterility in compact panicle cultivars, QTLs and candidate genes were identified for spikelet fertility percentage, panicle compactness and ethylene production that significantly influence the grain filling using recombinant inbred lines developed from a cross between indica rice cultivars, PDK Shriram (compact, high spikelet number) and Heera (lax, low spikelet number). Novel QTLs, qSFP1.1, qSFP3.1 and qSFP6.1 for spikelet fertility percentage; qIGS3.2 and qIGS4.1 for panicle compactness; and qETH1.2, qETH3.1 and qETH4.1 for ethylene production were consistently identified in both kharif seasons of 2017 and 2018. The comparative expression analysis of candidate genes like ERF3, AP2-like ethylene-responsive transcription factor, EREBP, GBSS1, E3 ubiquitin-protein ligase GW2, and LRR receptor-like serine/threonine-protein kinase ERL1 associated with identified QTLs revealed their role in poor grain filling of basal spikelets in dense panicle. These candidate genes thus could be important for improving grain filling in compact-panicle rice cultivars through biotechnological interventions.

Application of slow-controlled release fertilizer coordinates the carbon flow in carbon-nitrogen metabolism to effect rice quality

“…The expression of genes (OsSUT2 and OsCIN4) related to sucrose unloading (Sekhar et al, 2021), as well as sucrose content, in the UF, PCU, and BBF groups were not lower than that of CK group (Figure . 3 and 7), suggesting that the availability of carbohydrates was not restricted by these application of slowcontrolled release fertilizers. N-nutrient/metabolites and carbon metabolism are intricately interconnected (Yamakawa and Hakata, 2010).…”