Mao Ting, Zhu Mingdong, Sheng Zhonghua, Shao Gaoneng, Jiao Guiai, Mawia Amos Musyoki, Ahmad Shakeel, Xie Lihong, Tang Shaoqing, Wei Xiangjin, Hu Shikai, Hu Peisong
State Key Laboratory of Rice Biology, China National Center for Rice Improvement, China National Rice Research Institute, Hangzhou, 310006, China.
Liaoning Institute of Saline-Alkali and Utilization, Panjin, 124010, China.
Rice (N Y). 2021 Aug 10;14(1):74. doi: 10.1186/s12284-021-00517-5.
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) (YF47-gw8, YF47-gs3, YF47-gl7, YF47-qgl3 and YF47-tgw6) in Yanfeng 47(YF47) 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 YF47, excepted YF47-gs3, (2) The chalkiness degree was significantly reduced in all of the NILs, (3) In all of the NILs, YF47-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 YF47-gs3 and YF47-tgw6 were significantly higher than that of YF47, whereas YF47-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.
长粒粳稻因其优异的外观品质而具有较高的市场偏好。密穗直立1（dep1）基因已在中国高产粳稻品种的育种中广泛应用。然而，该基因导致籽粒短圆，因此在全球大米市场上吸引力较低。因此，通过将dep1与主效粒形基因结合来培育高产长粒粳稻品种是水稻产业的当务之急。到目前为止，多个粒形基因的作用机制已经得到明确阐述，然而，在直立穗型粳稻背景下，主效粒形基因对外观品质的影响尚需进一步阐明，因为详细报道有限。利用CRISPR/Cas9技术，创建了一系列以盐丰47（YF47）为背景的近等基因系（NILs）（YF47-gw8、YF47-gs3、YF47-gl7, YF47-qgl3和YF47-tgw6）。籽粒外观和产量构成分析表明：（1）除YF47-gs3外，所有NILs的粒长/粒宽比均显著高于YF47；（2）所有NILs垩白度均显著降低；（3）在所有NILs中，YF47-gw8籽粒的粒长/粒宽比最大，垩白度最低；（4）颖壳细胞组成和胚乳充实特性分别是影响粒形和籽粒垩白变异的两个关键因素；（5）由于千粒重显著增加，YF47-gs3和YF47-tgw6的产量显著高于YF47，而YF47-qgl3由于有效穗数和千粒重急剧下降，产量最低。所有结果表明，将dep1与主效粒形等位基因聚合是提高直立穗型粳稻外观品质的有效途径，由于外观品质和产量均得到提高，GS3和TGW6等位基因可直接应用于长粒形粳稻育种，编辑GW8导致外观品质优异但产量低，因此，该基因难以直接应用，但可作为核心种质资源。
