Luo Mingzhao, Zhang Shuo, Tang Chanjuan, Jia Guanqing, Tang Sha, Zhi Hui, Diao Xianmin
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Plant Sci. 2018 Nov 14;9:1650. doi: 10.3389/fpls.2018.01650. eCollection 2018.
C plants exhibit significantly higher photosynthetic, water and nutrient use efficiency compared with C plants. Kranz anatomy is associated with many C plants in which bundle sheath cells surround the veins and are themselves surrounded by mesophyll cells. This specialized Kranz anatomy is elucidated as an important contributor to C photosynthetic activities in C plant. Characterizing the molecular basis of Kranz structure formation has become a key objective for studies of C photosynthesis. However, severe mutants that specifically disrupt Kranz anatomy have not been identified. In this study, we detected 549 stable ethyl methane sulfonate-induced foxtail millet (cultivar Yugu1) mutants related to leaf development and photosynthesis among 2,709 mutants screened (M/M generation). The identified mutants included 52 that had abnormal leaf veins (with abnormal starch accumulation based on iodine staining). Each of the 52 mutants was characterized through an analysis of leaf morphology, and through microscopic observations of leaf tissue sections embedded in resin and paraffin. In total, 14 mutants were identified with abnormal Kranz structures exemplified by small bundle sheath cell size. Additional phenotypes of the mutants included poorly differentiated mesophyll and bundle sheath cells, increased vein density and the absence of chloroplasts in the bundle sheath cells. Kranz structure mutations were accompanied by varying leaf thickness, implying these mutations induced complex effects. We identified mutations related to Kranz structure development in this trial, which may be useful for the mapping and cloning of genes responsible for mediating Kranz structure development.
与C₃植物相比，C₄植物表现出显著更高的光合、水分和养分利用效率。花环解剖结构与许多C₄植物相关，在这些植物中，维管束鞘细胞围绕着叶脉，并且它们自身又被叶肉细胞包围。这种特殊的花环解剖结构被认为是C₄植物中C₄光合活动的重要贡献者。表征花环结构形成的分子基础已成为C₄光合作用研究的关键目标。然而，尚未鉴定出特异性破坏花环解剖结构的严重突变体。在本研究中，我们在筛选的2709个突变体（M₁/M₂代）中检测到549个与叶片发育和光合作用相关的稳定的甲磺酸乙酯诱导的谷子（品种豫谷1）突变体。鉴定出的突变体包括52个叶脉异常的突变体（基于碘染色淀粉积累异常）。通过对叶片形态的分析以及对嵌入树脂和石蜡中的叶片组织切片的显微镜观察，对这52个突变体中的每一个进行了表征。总共鉴定出14个具有异常花环结构的突变体，其特征是维管束鞘细胞尺寸小。这些突变体的其他表型包括叶肉和维管束鞘细胞分化不良、叶脉密度增加以及维管束鞘细胞中没有叶绿体。花环结构突变伴随着叶片厚度的变化，这意味着这些突变产生了复杂的影响。我们在本试验中鉴定出与花环结构发育相关的突变，这可能有助于负责介导花环结构发育的基因的定位和克隆。
