Guo Shangjing, Zhou Guoliang, Wang Jinglu, Lu Xianju, Zhao Huan, Zhang Minggang, Guo Xinyu, Zhang Ying
College of Agronomy, Liaocheng University, Liaocheng 252059, China.
Beijing Key Lab of Digital Plant, Research Center of Information Technology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
Plants (Basel). 2022 May 18;11(10):1339. doi: 10.3390/plants11101339.
The vascular bundle of the shank is an important 'flow' organ for transforming maize biological yield to grain yield, and its microscopic phenotypic characteristics and genetic analysis are of great significance for promoting the breeding of new varieties with high yield and good quality. In this study, shank CT images were obtained using the standard process for stem micro-CT data acquisition at resolutions up to 13.5 μm. Moreover, five categories and 36 phenotypic traits of the shank including related to the cross-section, epidermis zone, periphery zone, inner zone and vascular bundle were analyzed through an automatic CT image process pipeline based on the functional zones. Next, we analyzed the phenotypic variations in vascular bundles at the base of the shank among a group of 202 inbred lines based on comprehensive phenotypic information for two environments. It was found that the number of vascular bundles in the inner zone (IZ_VB_N) and the area of the inner zone (IZ_A) varied the most among the different subgroups. Combined with genome-wide association studies (GWAS), 806 significant single nucleotide polymorphisms (SNPs) were identified, and 1245 unique candidate genes for 30 key traits were detected, including the total area of vascular bundles (VB_A), the total number of vascular bundles (VB_N), the density of the vascular bundles (VB_D), etc. These candidate genes encode proteins involved in lignin, cellulose synthesis, transcription factors, material transportation and plant development. The results presented here will improve the understanding of the phenotypic traits of maize shank and provide an important phenotypic basis for high-throughput identification of vascular bundle functional genes of maize shank and promoting the breeding of new varieties with high yield and good quality.
玉米茎秆维管束是将生物产量转化为籽粒产量的重要“流”器官，其微观表型特征及遗传分析对推动高产优质新品种选育具有重要意义。本研究采用茎微CT数据采集标准流程，获取分辨率高达13.5μm的茎秆CT图像。此外，通过基于功能区的自动CT图像处理流程，分析了茎秆的五类36个表型性状，包括与横截面、表皮区、外周区、内部区域和维管束相关的性状。接下来，基于两个环境下的综合表型信息，分析了202个自交系群体中茎基部维管束的表型变异。结果发现，不同亚组中内部区域维管束数量（IZ_VB_N）和内部区域面积（IZ_A）的变异最大。结合全基因组关联研究（GWAS），鉴定出806个显著单核苷酸多态性（SNP），检测到30个关键性状的1245个独特候选基因，包括维管束总面积（VB_A）、维管束总数（VB_N）、维管束密度（VB_D）等。这些候选基因编码参与木质素、纤维素合成、转录因子、物质运输和植物发育的蛋白质。本文结果将增进对玉米茎秆表型性状的理解，为高通量鉴定玉米茎秆维管束功能基因及推动高产优质新品种选育提供重要表型依据。
