PDF(Pubmed)
Abstract：
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 QCL.qau-4BS and QCL.qau-4DS were detected, which could explain 9.1%-22.2% of the phenotypic variances across environments on Rht-B1 and Rht-D1 loci, respectively. Several studies have reported that Rht-B1b may reduce the length of wheat CL but no study has been carried out at molecular level. In order to verify that the Rht-B1 gene is the functional gene for the 4B QTL, an overexpression line Rht-B1b-OE and a CRISPR/SpCas9 line Rht-B1b-KO were studied. The results showed that Rht-B1b overexpression could reduce the CL, while loss-of-function of Rht-B1b would increase the CL relative to that of the null transgenic plants (TNL). To dissect the underlying regulatory mechanism of Rht-B1b on CL, comparative RNA-Seq was conducted between Rht-B1b-OE and TNL. Transcriptome profiles revealed a few key pathways involving the function of Rht-B1b 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.
摘要：
小麦胚芽鞘是一种鞘状结构，有助于将第一片叶子从胚胎输送到土壤表面。这里,通过高密度IlluminaiSelect90K测定法对由来自Zhou8425B×中国春季杂交的245个品系组成的RIL种群进行了基因分型，以进行胚芽鞘长度（CL）QTL定位。CL的三个QTL定位在2BL染色体上，4BS和4DS。其中,QCL两个主要的QTL。qau-4BS和QCL。检测到qau-4DS，这可以解释不同环境中Rht-B1和Rht-D1位点的表型变异的9.1%-22.2%，分别。一些研究报道Rht-B1b可能会减少小麦CL的长度，但尚未在分子水平上进行研究。为了验证Rht-B1基因是4BQTL的功能基因,研究了过表达系Rht-B1b-OE和CRISPR/SpCas9系Rht-B1b-KO。结果表明,Rht-B1b过表达能降低CL,而Rht-B1b的功能丧失会相对于无效转基因植物（TNL）的CL增加。剖析Rht-B1b对CL的潜在调控机制，在Rht-B1b-OE和TNL之间进行比较RNA-Seq。转录组图谱揭示了一些关键途径，涉及Rht-B1b在胚芽鞘发育中的功能，包括植物激素,昼夜节律和淀粉和蔗糖代谢。我们的发现可能有助于小麦育种更长的胚芽鞘，以提高幼苗的早期活力，从而更好地渗透到干旱地区的土壤地壳中。
