Effects of Grain Shape Genes Editing on Appearance Quality of Erect-Panicle Geng/Japonica Rice

Abstract

Long grain geng/japonica rice has a higher market preference due its excellent appearance quality. The dense and erect-panicle 1 (dep1) gene has been widely used in the breeding of high-yielding geng/japonica rice cultivars in China. However, this gene causes short and round grain shape thus making it less attractive in global rice markets. Therefore, breeding of high-yielding long-grain geng/japonica rice cultivars by incorporating dep1 with major-effect grain shape gene is of high priority in rice industry. Up to now, multiple grain shape genes’ effect mechanism has been clearly elaborated, however, under the background of erect-panicle geng/japonica rice, the effect of major grain shape genes on the appearance quality need to be further clarified, as detailed reports are limited. Utilizing CRISPR/Cas9 technology, a series of near-isogenic lines (NILs) (YF47dep1-gw8, YF47dep1-gs3, YF47dep1-gl7, YF47dep1-qgl3 and YF47dep1-tgw6) in Yanfeng 47(YF47dep1) background were created. Grain appearance and yield components analysis showed that: (1) All NILs’ grain length to width ratio was significantly increased compared to that of YF47dep1, excepted YF47dep1-gs3, (2) The chalkiness degree was significantly reduced in all of the NILs, (3) In all of the NILs, YF47dep1-gw8 grains exhibited the greatest length to width ratio and the lowest chalkiness degree, (4) The composition of glume cells and filling characteristics of the endosperm were two key factors contributing grain shape and grain chalk variations, respectively, and v) Owning to a substantial increase in the thousand grain weight, the yields of YF47dep1-gs3 and YF47dep1-tgw6 were significantly higher than that of YF47dep1, whereas YF47dep1-qgl3 exhibited the lowest yield because of a dramatic decrease in the effective panicle number and thousand grain weight. All the results revealed that pyramiding dep1 with major-effect grain shape alleles was an effective approach to improving the appearance quality of erect-panicle geng/japonica rice, owning to both of the appearance quality and yield improvement, GS3 and TGW6 alleles can be applied directly for breeding long-grain shape geng/japonica rice, and editing GW8 resulted in excellent appearance quality but low yield, therefore, this gene would be difficult to use directly but can be considered as the core germplasm resource.

Dissecting the Molecular Basis for Genetic Improvement of Rice

“…CRISPR-Cas9 technology allows site-directed editing of target genes, which has important breeding value for the targeted breeding of speci c traits of crops. At present, researchers use CRISPR/Cas9 technology to perform gene editing on Wx [48] , GL7 [49] , fgr [49] , etc., to improve rice quality. We used CRISPR/Cas9 technology to perform gene editing on the GS3 of Mei 1B to obtain a highquality maintainer line Mei 2B, and nally obtained a high-quality sterile line Mei 2A by hybridization, backcrossing, and other methods [12] .…”

Understanding the regulation of cereal grain filling: The way forward

“…Rapid breakthroughs in gene editing technology have made it possible to easily knock out negative regulators of grain filling without producing transgenic plants. Using this technique, novel alleles of different QTLs can be quickly generated in different elite cultivar backgrounds (Shen et al, 2018; Mao et al, 2021). In addition to coding regions, the promoter regions of genes can also be edited to generate useful alleles with altered expression patterns, as demonstrated by the efficient editing of the promoters of SCM3, IPA1, Wx , and GWD1 in rice (Cui et al, 2020; Zeng et al, 2020; Wang et al, 2021b; Song et al, 2022) and SIWUS and SICLV3 in tomato ( Solanum lycopersicum ) (Rodriguez‐Leal et al, 2017).…”

Dynamic monitoring of TGW6 by selective autophagy during grain development in rice

“…THOUSAND‐GRAIN WEIGHT 6 emerged during breeding selection of rice ( Oryza sativa ; Ishimaru et al ., 2013) as a superior target and has been successfully deployed for molecular breeding of high‐yielding elite varieties with superior grain quality (Li et al ., 2019; Mao et al ., 2021). Loss of function of TGW6 increases the grain length and grain yield, accompanied with the lower chalky grain ratio under high temperature (Ishimaru et al ., 2013).…”