Expression of C4 Genes in Development of Maize Leaf Cell Types

像叶子这样的复杂器官的发育依赖于多种细胞类型的整合分化。在与C4固碳相互作用的酶基因中，促进玉米叶片中两种相互作用的光合作用细胞类型(束鞘和叶肉)分化的基因表达变化最为显著。每种C4酶都特定于一种细胞类型，并在叶片内以固定的空间模式积累。在发育过程中，每个光合作用C4基因在两种叶细胞类型中的一种中特定地发生表达的方式尚不清楚。一些C4酶是小的多基因家族的成员，这些家族也提供执行家务管理功能的同功酶亚型，其调节方式与光合作用形式截然不同。该项目旨在通过直接比较光合作用和非光合作用异构体的基因来扩展先前对C4酶基因和叶片细胞发育模式的研究。基因克隆、测序和比较研究还将提供基因特异性探针，以帮助随后分析细胞特异性和器官特异性基因表达。

The development of a complex organ such as a leaf depends on the integrated differentiation of multiple cell types. The alterations in gene expression which contribute to the differentiation of the two interacting photosynthetic cell types in maize leaves (bundle sheath and mesophyll) are most dramatic among the genes for enzymes which interact in C4 carbon fixation. Each C4 enzyme is specific to one cell type, and accumulates in a fixed spatial pattern within the leaf. The means by which expression of each photosynthetic C4 gene occurs specifically in one of the two leaf cell types during development are unknown. Several of the C4 enzymes are members of small multigene families which also contribute enzyme isoforms which perform housekeeping functions and are regulated in drastically differing manner from the photosynthetic forms. This project seeks to extend previous studies of C4 enzyme genes and patterns of cellular development in leaves by directly comparing genes for the photosynthetic and non- photosynthetic isoforms. The gene cloning, sequencing and comparative studies will also provide gene-specific probes to aid in subsequent analysis of cell-specific and organ-specific gene expression.