Liang Chenggang, Wei Chunyu, Wang Li, Guan Zhixiu, Shi Taoxiong, Huang Juan, Li Bin, Lu Yang, Liu Hui, Wang Yan
Research Center of Buckwheat Industry Technology, School of Life Sciences, Guizhou Normal University, Guiyang, China.
Guizhou Biotechnology Institute, Guizhou Academy of Agricultural Sciences, Guiyang, China.
Front Plant Sci. 2022 Apr 27;13:815131. doi: 10.3389/fpls.2022.815131. eCollection 2022.
Gravity is known as an important environmental factor involved in the regulation of plant architecture. To identify genes related to the gravitropism of Tartary buckwheat, a creeping line was obtained and designated as from the mutant bank by Co-γ ray radiation. Genetic analysis indicated that the creeping phenotype of was attributed to a single recessive locus. As revealed by the horizontal and inverted suspension tests, was completely lacking in shoot negative gravitropism. The creeping growth of occurred at the early seedling stage, which could not be recovered by exogenous heteroauxin, hormodin, α-rhodofix, or gibberellin. Different from the well-organized and equivalent cell elongation of wild type (WT), exhibited dilated, distorted, and abnormally arranged cells in the bending stem. However, no statistical difference of indole-3-acetic acid (IAA) levels was found between the far- and near-ground bending sides in , which suggests that the asymmetric cell elongation of was not induced by auxin gradient. Whereas, showed up-expressed gibberellin-regulated genes by quantitative real-time PCR (qRT-PCR) as well as significantly higher levels of gibberellin, suggesting that gibberellin might be partly involved in the regulation of creeping growth in . RNA sequencing (RNA-seq) identified a number of differentially expressed genes (DEGs) related to gravitropism at stages I (before bending), II (bending), and III (after bending) between WT and . Venn diagram indicated that only was down-expressed at stages I [Log fold change (LogFC): -3.20], II (LogFC: -4.97), and III (LogFC: -1.23) in , compared with WT. Gene sequencing revealed that a fragment deletion occurred in the coding region of , which induced the destruction of a pbH domain in of . qRT-PCR indicated that was extremely down-expressed in at stage II (0.02-fold of WT). Meanwhile, showed the affected expression of lignin- and cellulose-related genes and cumulatively abnormal levels of pectin, lignin, and cellulose. These results demonstrate the possibility that functions as the key gene that could mediate primary cell wall metabolism and get involved in the asymmetric cell elongation regulation of .
重力是已知参与植物形态调控的重要环境因素。为了鉴定与苦荞向地性相关的基因，通过Co-γ射线辐射从突变体库中获得了一个匍匐系并命名为[具体名称缺失]。遗传分析表明，[具体名称缺失]的匍匐表型归因于一个单隐性位点。水平和倒置悬挂试验表明，[具体名称缺失]完全缺乏茎的负向地性。[具体名称缺失]的匍匐生长发生在幼苗早期，外源异生长素、激素调节剂、α-固氮菌或赤霉素均不能使其恢复。与野生型（WT）细胞伸长组织良好且均匀不同，[具体名称缺失]在弯曲茎中表现出细胞扩张、扭曲和排列异常。然而，在[具体名称缺失]中，远地侧和近地侧弯曲部位的吲哚-3-乙酸（IAA）水平没有统计学差异，这表明[具体名称缺失]的不对称细胞伸长不是由生长素梯度诱导的。而通过定量实时PCR（qRT-PCR）分析，[具体名称缺失]中赤霉素调节基因呈上调表达，且赤霉素水平显著更高，这表明赤霉素可能部分参与了[具体名称缺失]匍匐生长的调控。RNA测序（RNA-seq）鉴定了野生型和[具体名称缺失]在阶段I（弯曲前）、II（弯曲时）和III（弯曲后）与向地性相关的一些差异表达基因（DEG）。维恩图表明，与野生型相比，[具体名称缺失]仅在阶段I [对数变化倍数（LogFC）：-3.20]、II（LogFC：-4.97）和III（LogFC：-1.23）时下调表达。基因测序显示，[具体名称缺失]的编码区发生了片段缺失，导致[具体名称缺失]的一个pbH结构域被破坏。qRT-PCR表明，[具体名称缺失]在阶段II时极低表达（为野生型的0.02倍）。同时，[具体名称缺失]中木质素和纤维素相关基因的表达受到影响，果胶、木质素和纤维素水平累积异常。这些结果证明了[具体名称缺失]作为关键基因发挥作用的可能性，该基因可介导初生细胞壁代谢并参与[具体名称缺失]的不对称细胞伸长调控。
