Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA.
USDA-ARS Appalachian Fruit Research Station, Kearneysville, WV, 25430, USA.
Sci Rep. 2020 Apr 8;10(1):6051. doi: 10.1038/s41598-020-62962-4.
TAC1 and LAZY1 are members of a gene family that regulates lateral shoot orientation in plants. TAC1 promotes outward orientations in response to light, while LAZY1 promotes upward shoot orientations in response to gravity via altered auxin transport. We performed genetic, molecular, and biochemical assays to investigate possible interactions between these genes. In Arabidopsis they were expressed in similar tissues and double mutants revealed the wide-angled lazy1 branch phenotype, indicating it is epistatic to the tac1 shoot phenotype. Surprisingly, the lack of TAC1 did not influence gravitropic shoot curvature responses. Combined, these results suggest TAC1 might negatively regulate LAZY1 to promote outward shoot orientations. However, additional results revealed that TAC1- and LAZY1 influence on shoot orientation is more complex than a simple direct negative regulatory pathway. Transcriptomes of Arabidopsis tac1 and lazy1 mutants compared to wild type under normal and gravistimulated conditions revealed few overlapping differentially expressed genes. Overexpression of each gene did not result in major branch angle differences. Shoot tip hormone levels were similar between tac1, lazy1, and Col, apart from exceptionally elevated levels of salicylic acid in lazy1. The data presented here provide a foundation for future study of TAC1 and LAZY1 regulation of shoot architecture.
TAC1 和 LAZY1 是调节植物侧枝方向的基因家族的成员。TAC1 促进光响应的外向方向，而 LAZY1 通过改变生长素运输促进重力响应的向上的枝条方向。我们进行了遗传、分子和生化分析，以研究这些基因之间可能的相互作用。在拟南芥中，它们在相似的组织中表达，双突变体显示出宽角懒 1 分支表型，表明它是对 tac1 枝条表型的上位性。令人惊讶的是，缺乏 TAC1 并不影响向光性枝条曲率反应。综合这些结果表明，TAC1 可能通过负调控 LAZY1 来促进外向枝条方向。然而，其他结果表明，TAC1 和 LAZY1 对枝条方向的影响比简单的直接负调控途径更为复杂。与野生型相比，拟南芥 tac1 和 lazy1 突变体在正常和重力刺激条件下的转录组显示出很少的重叠差异表达基因。每种基因的过表达并没有导致主要的分支角度差异。除了 lazy1 中异常升高的水杨酸水平外，tac1、lazy1 和 Col 之间的枝条顶端激素水平相似。这里呈现的数据为未来研究 TAC1 和 LAZY1 对枝条结构的调控提供了基础。
