Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, 100083 Beijing, China.
Center for Statistical Genetics, Pennsylvania State University, Hershey, PA 17033, USA.
Front Biosci (Landmark Ed). 2021 Nov 30;26(11):988-1000. doi: 10.52586/5003.
: Plants have evolved the dual capacity for maximizing light assimilation through stem growth (phototropism) and maximizing water and nutrient absorption through root growth (gravitropism). Previous studies have revealed the physiological and molecular mechanisms of these two processes, but the genetic basis for how gravitropism and phototropism interact and coordinate with one another to determine plant growth remains poorly understood. : We designed a seed germination experiment using a full-sib F1 family of to simultaneously monitor the gravitropic growth of the radicle and the phototropic growth of the plumule throughout seedling ontogeny. We implemented three functional mapping models to identify quantitative trait loci (QTLs) that regulate gravitropic and phototropic growth. Univariate functional mapping dissected each growth trait separately, bivariate functional mapping mapped two growth traits simultaneously, and composite functional mapping mapped the sum of gravitropic and phototropic growth as a main axis. : Bivariate model detected 8 QTLs for gravitropism and phototropism (QWRF, GLUR, F-box, PCFS4, UBQ, TAF12, BHLH95, TMN8), composite model detected 7 QTLs for growth of main axis (ATL8, NEFH, PCFS4, UBQ, SOT16, MOR1, PCMP-H), of which, PCFS4 and UBQ were pleiotropically detected with the both model. Many of these QTLs are situated within the genomic regions of candidate genes. : The results from our models provide new insight into the mechanisms of genetic control of gravitropism and phototropism in a desert tree, and will stimulate our understanding of the relationships between gravity and light signal transduction pathways and tree adaptation to arid soil.
植物进化出了双重能力，既能通过茎的生长（向光性）最大限度地吸收光，又能通过根的生长（向地性）最大限度地吸收水和养分。先前的研究揭示了这两个过程的生理和分子机制，但对于向地性和向光性如何相互作用和协调以决定植物生长的遗传基础，仍知之甚少。
我们设计了一个种子萌发实验，使用一个全同胞 F1 家系，同时监测整个幼苗发生过程中胚根的向地性生长和胚芽的向光性生长。我们实施了三种功能作图模型，以鉴定调节向地性和向光性生长的数量性状位点（QTL）。单变量功能作图分别剖析了每个生长性状，双变量功能作图同时映射了两个生长性状，而复合功能作图则将向地性和向光性生长的总和作为主轴进行映射。
双变量模型检测到 8 个向光性和向地性的 QTL（QWRF、GLUR、F-box、PCFS4、UBQ、TAF12、BHLH95、TMN8），复合模型检测到 7 个主轴生长的 QTL（ATL8、NEFH、PCFS4、UBQ、SOT16、MOR1、PCMP-H），其中 PCFS4 和 UBQ 被两个模型检测到具有多效性。这些 QTL 中的许多位于候选基因的基因组区域内。
我们模型的结果为深入了解沙漠树木向光性和向地性的遗传控制机制提供了新的视角，并将激发我们对重力和光信号转导途径与树木适应干旱土壤之间关系的理解。
