Jian Hongju, Yang Bo, Zhang Aoxiang, Zhang Li, Xu Xinfu, Li Jiana, Liu Liezhao
Chongqing Engineering Research Center for Rapeseed, College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing, P. R. China.
PLoS One. 2017 Jan 9;12(1):e0169641. doi: 10.1371/journal.pone.0169641. eCollection 2017.
Leaf size and shape play important roles in agronomic traits, such as yield, quality and stress responses. Wide variations in leaf morphological traits exist in cultivated varieties of many plant species. By now, the genetics of leaf shape and size have not been characterized in Brassica napus. In this study, a population of 172 recombinant inbred lines (RILs) was used for quantitative trait locus (QTL) analysis of leaf morphology traits. Furthermore, fresh young leaves of extreme lines with more leaf lobes (referred to as 'A') and extreme lines with fewer lobes (referred to as 'B') selected from the RIL population and leaves of dissected lines (referred to as 'P') were used for transcriptional analysis. A total of 31 QTLs for the leaf morphological traits tested in this study were identified on 12 chromosomes, explaining 5.32-39.34% of the phenotypic variation. There were 8, 6, 2, 5, 8, and 2 QTLs for PL (petiole length), PN (lobe number), LW (lamina width), LL (Lamina length), LL/LTL (the lamina size ratio) and LTL (leaf total length), respectively. In addition, 74, 1,166 and 1,272 differentially expressed genes (DEGs) were identified in 'A vs B', 'A vs P' and 'B vs P' comparisons, respectively. The Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to predict the functions of these DEGs. Gene regulators of leaf shape and size, such as ASYMMETRIC LEAVES 2, gibberellin 20-oxidase 3, genes encoding gibberellin-regulated family protein, genes encoding growth-regulating factor and KNOTTED1-like homeobox were also detected in DEGs. After integrating the QTL mapping and RNA sequencing data, 33 genes, including a gene encoding auxin-responsive GH3 family protein and a gene encoding sphere organelles protein-related gene, were selected as candidates that may control leaf shape. Our findings should be valuable for studies of the genetic control of leaf morphological trait regulation in B. napus.
叶片大小和形状在农艺性状中发挥着重要作用，如产量、品质和胁迫响应。许多植物物种的栽培品种中叶片形态性状存在广泛变异。到目前为止，甘蓝型油菜叶片形状和大小的遗传学尚未得到表征。在本研究中，利用一个由172个重组自交系（RIL）组成的群体对叶片形态性状进行数量性状位点（QTL）分析。此外，从RIL群体中选取具有较多叶裂片的极端系（称为“A”）和具有较少叶裂片的极端系（称为“B”）的新鲜幼叶以及分离系（称为“P”）的叶片用于转录分析。本研究中测试的叶片形态性状共鉴定出31个QTL，分布在12条染色体上，解释了5.32%至39.34%的表型变异。叶柄长度（PL）、裂片数（PN）、叶片宽度（LW）、叶片长度（LL）、叶片大小比（LL/LTL）和叶全长（LTL）的QTL分别有8个、6个、2个、5个、8个和2个。此外，在“A与B”、“A与P”和“B与P”的比较中分别鉴定出74个、1166个和1272个差异表达基因（DEG）。利用基因本体论（GO）和京都基因与基因组百科全书（KEGG）数据库预测这些DEG的功能。在DEG中还检测到叶片形状和大小的基因调控因子，如不对称叶片2、赤霉素20-氧化酶3、编码赤霉素调节家族蛋白的基因、编码生长调节因子的基因和类KNOTTED1同源框基因。整合QTL定位和RNA测序数据后，选择了33个基因作为可能控制叶片形状的候选基因，其中包括一个编码生长素响应GH3家族蛋白的基因和一个编码球形细胞器蛋白相关基因的基因。我们的研究结果对于甘蓝型油菜叶片形态性状调控的遗传控制研究具有重要价值。
