MIXTA/MIXTA-like基因特征及其对植物表皮细胞分化的调控

植物表皮细胞是植物最外层直接与环境相互作用的细胞,依据其不同功能,分化形成多种具有防卫功能的特化细胞结构,在植物防御、减少蒸腾、授粉媒介吸引、种子散布、次生代谢产物合成与贮存等方面起着重要作用。研究发现MIXTA/MIXTA-like是多种植物表皮细胞分化的关键调控因子。在不同植物中,MIXTA/MIXTA-like作用部位(主要集中在花瓣、叶片、胚珠和子房)和调节方式不同,但最终都是通过调控表皮细胞分化发挥作用。MIXTA/MIXTA-like在表皮毛的形成、角质层生物合成、锥形表皮细胞的分化过程中起着重要的调节作用,其中植物表皮毛发育是一个研究热点。植物表皮毛有多种不同的功能:如叶片被毛是植物抵御取食昆虫的重要表型特征;法国梧桐、杨树、柳树飞絮都是种子成熟过程中表皮毛发育的结果;而黄花蒿中,青蒿素主要在腺毛中合成和储存。因此,开展植物表皮毛发育和调控机制研究具有重要意义。笔者梳理了MIXTA/MIXTA-like基因的特征及其在不同植物表皮细胞分化过程中的生物学功能,阐述了木本植物表皮毛发育调控的分子机制,为加速林木表皮毛发育相关性状的新品种培育提供借鉴。

Characteristics of MIXTA/MIXTA-like genes and their functions in regulating plant epidermal cells differentiation

Plant epidermal cells are the outermost cells that directly interact with ambient conditions. According to their functional roles, epidermal cells differentiate into a variety of specialized cell structures, which participate in activities such as plant defense, evaporation reduction, pollinator attraction, seed dispersal, and the synthesis and storage of se-condary metabolites. MIXTA/MIXTA-like genes have been identified as key regulators of epidermal cell differentiation in many plants. These genes may function in different tissues (e.g., petals, leaves, ovules and ovaries) in different plants by regulating the differentiation of epidermal cells. They also play essential roles in trichome formation, cuticle biosynthesis, conical epidermal cell differentiation, and in initializing seed hair development. Among which, trichome development is a hot research topic because of its functional role. For instance, leaf indumentum is deemed as an important morphological feature in the defense against phytophagous insects, and seed hairs dispersed from poplars, willows and chinars are all differentiated from epidermal cells during seed maturation; whereas artemisinin is synthesized and stored in the glandular hairs of Artemisia annua. Here, we review and summarize the characteristics of MIXTA/MIXTA-like genes, as well as their biological functions in regulating epidermal cell differentiation. This paper provides essential information for facilitating studies on the molecular mechanisms underlying epidermal cell differentiation and for accelerating the breeding program of traits related to epidermal cell differentiation.