PDF(Pubmed)
Abstract：
Leaf shape is considered to be one of the most significant agronomic traits in crop breeding. However, the molecular basis underlying leaf morphogenesis in cotton is still largely unknown. In this study, through genetic mapping and molecular investigation using a natural cotton mutant cu with leaves curling upward, the causal gene GHCU is successfully identified as the key regulator of leaf flattening. Knockout of GHCU or its homolog in cotton and tobacco using CRISPR results in abnormal leaf shape. It is further discovered that GHCU facilitates the transport of the HD protein KNOTTED1-like (KNGH1) from the adaxial to the abaxial domain. Loss of GHCU function restricts KNGH1 to the adaxial epidermal region, leading to lower auxin response levels in the adaxial boundary compared to the abaxial. This spatial asymmetry in auxin distribution produces the upward-curled leaf phenotype of the cu mutant. By analysis of single-cell RNA sequencing and spatiotemporal transcriptomic data, auxin biosynthesis genes are confirmed to be expressed asymmetrically in the adaxial-abaxial epidermal cells. Overall, these findings suggest that GHCU plays a crucial role in the regulation of leaf flattening through facilitating cell-to-cell trafficking of KNGH1 and hence influencing the auxin response level.
摘要：
叶片形状被以为是作物育种中最显著的农艺性状之一。然而,棉花叶片形态发生的分子基础在很大程度上仍然未知。在这项研究中,通过使用叶片向上卷曲的天然棉花突变体Cu的遗传作图和分子研究，因果基因GHCU被成功鉴定为叶片变平的关键调节因子。使用CRISPR在棉花和烟草中敲除GHCU或其同源物导致异常的叶片形状。进一步发现GHCU促进HD蛋白KNOTTED1样(KNGH1)从正面向背面结构域的转运。GHCU功能的丧失将KNGH1限制在近轴表皮区域，导致与后轴边界相比，近端边界的生长素响应水平较低。生长素分布的这种空间不对称性产生了cu突变体的向上卷曲的叶片表型。通过分析单细胞RNA测序和时空转录组数据，证实生长素生物合成基因在近轴-后轴表皮细胞中不对称表达。总的来说,这些发现表明，GHCU通过促进KNGH1的细胞间运输并因此影响生长素响应水平，在调节叶片变平中起着至关重要的作用。
