植物结构是决定牧草生物量和草皮结构的重要农艺性状。IGT家族在植物引力作用中起着举足轻重的作用,包括重力响应和植物结构的调制。我们之前已经证明了LjLAZY3,IGT基因之一,在日本血吸虫的根系向向重力中起着独特的作用。然而,在该物种中,LAZY蛋白对芽引力的功能知之甚少。在这项研究中,我们在日本乳杆菌基因组中鉴定了9个IGT基因,根据18种豆类的IGT蛋白的系统发育关系,将其分为四个分支:LAZY1,NGR(根的负重力响应),IGT-like,和TAC1。我们发现前三个分支中的LAZY基因在调节日本血吸虫的植物向向重力方面表现出独特的作用,其具体影响如下。LAZY1基因突变,LjLAZY1缺陷了下胚轴的重力响应,而不影响主茎的分支角。相比之下,NGR基因的过表达,LjLAZY3,基本上调制了枝条的引力,导致侧枝角度较窄。此外,它增强了枝条的重力反应。另一个NGR基因的过表达,LjLAZY4特别减小了主茎的分支角度并降低了植物的身材,而不影响芽的重力响应。IGT样基因LjLAZY2过表达的表型与LjLAZY4相同。虽然IGT样基因LjLAZY5的过表达没有诱导分支角度的任何可观察到的变化,植物高度,或重力响应。此外,LjLAZYs选择性地与不同的BRXL和RLD蛋白相互作用,这应该是决定它们在控制日本血吸虫器官结构中不同功能的重要因素。我们的结果加深了对LjLAZY家族及其在日本L.japonicus植物结构改良中的潜力的理解。
Plant architecture is an important agronomic trait to determine the biomass and sward structure of forage grass. The IGT family plays a pivotal role in plant gravitropism, encompassing both the gravitropic response and the modulation of plant architecture. We have previously shown that LjLAZY3, one of the IGT genes, plays a distinct role in root gravitropism in L. japonicus. However, the function of LAZY proteins on shoot gravitropism in this species is poorly understood. In this study, we identified nine IGT genes in the L. japonicus genome, which have been categorized into four clades based on the phylogenetic relationships of IGT proteins from 18 legumes: LAZY1, NGR (NEGATIVE GRAVITROPIC RESPONSE OF ROOTS), IGT-LIKE, and TAC1. We found that LAZY genes in the first three clades have demonstrated distinct role for modulating plant gravitropism in L. japonicus with specific impacts as follows. Mutation of the LAZY1 gene, LjLAZY1, defected the gravitropic response of hypocotyl without impacting the main stem\'s branch angle. In contrast, the overexpression of the NGR gene, LjLAZY3, substantially modulated the shoot\'s gravitropism, leading to narrower lateral branch angles. Additionally, it enhanced the shoots\' gravitropic response. The overexpression of another NGR gene, LjLAZY4, specifically reduced the main stem\'s branch angle and decreased plant stature without affecting the shoot gravitropic response. The phenotype of IGT-LIKE gene LjLAZY2 overexpression is identical to that of LjLAZY4. While overexpression of the IGT-LIKE gene LjLAZY5 did not induce any observable changes in branch angle, plant height, or gravitropic response. Furthermore, the LjLAZYs were selectively interacted with different BRXL and RLD proteins, which should the important factor to determine their different functions in controlling organ architecture in L. japonicus. Our results deepen understanding of the LjLAZY family and its potential for plant architecture improvement in L. japonicus.