AUTHOR=Xu Dengan , Hao Qianlin , Yang Tingzhi , Lv Xinru , Qin Huimin , Wang Yalin , Jia Chenfei , Liu Wenxing , Dai Xuehuan , Zeng Jianbin , Zhang Hongsheng , He Zhonghu , Xia Xianchun , Cao Shuanghe , Ma Wujun 

TITLE=Impact of “Green Revolution” gene Rht-B1b on coleoptile length of wheat

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1147019

DOI=10.3389/fpls.2023.1147019

ISSN=1664-462X

ABSTRACT=<p>Wheat coleoptile is a sheath-like structure that helps to deliver the first leaf from embryo to the soil surface. Here, a RIL population consisting of 245 lines derived from Zhou 8425B × Chinese Spring cross was genotyped by the high-density Illumina iSelect 90K assay for coleoptile length (CL) QTL mapping. Three QTL for CL were mapped on chromosomes 2BL, 4BS and 4DS. Of them, two major QTL <italic>QCL.qau-4BS</italic> and <italic>QCL.qau-4DS</italic> were detected, which could explain 9.1%–22.2% of the phenotypic variances across environments on <italic>Rht-B1</italic> and <italic>Rht-D1</italic> loci, respectively. Several studies have reported that <italic>Rht-B1b</italic> may reduce the length of wheat CL but no study has been carried out at molecular level. In order to verify that the <italic>Rht-B1</italic> gene is the functional gene for the 4B QTL, an overexpression line <italic>Rht-B1b</italic>-OE and a CRISPR/SpCas9 line <italic>Rht-B1b</italic>-KO were studied. The results showed that <italic>Rht-B1b</italic> overexpression could reduce the CL, while loss-of-function of <italic>Rht-B1b</italic> would increase the CL relative to that of the null transgenic plants (TNL). To dissect the underlying regulatory mechanism of <italic>Rht-B1b</italic> on CL, comparative RNA-Seq was conducted between <italic>Rht-B1b</italic>-OE and TNL. Transcriptome profiles revealed a few key pathways involving the function of <italic>Rht-B1b</italic> in coleoptile development, including phytohormones, circadian rhythm and starch and sucrose metabolism. Our findings may facilitate wheat breeding for longer coleoptiles to improve seedling early vigor for better penetration through the soil crust in arid regions.</p>