玉米茎秆细胞壁形成及冠菌素调控茎秆抗倒伏机理的研究

In corn cultivation measures, chemical regulation is one of the most feasible means to construct the ideal group and enhance the lodging resistance. As a new plant growth regulator, coronatine can regulate plant growth, increase cytoderm thickness and enhance plant resistance. In this study, RILs, B73 inbred lines, and the directed mutagenesis and overexpression plant of the maize encoding xyloglucan endo-transglycosylase/hydrolase gene were selected as the research materials. We intend to research the effects of spraying coronatine on the leaf at jointing stage on the agronomic characters of stems, the microstructure morphology of cytoderm, lignin and cellulose accumulation and the activity of key enzyme in regulating cell wall synthesis and expression of related genes. At the same time, the traits of phenotypic analysis related lodging resistance, joint variance analysis and multi-generation combined separation analysis methods for the lodging resistance related traits of various branches in the RILs were studied to analyze the QTL positioning of the lodging resistance genes in the stem. The aim of this study is to analyze the molecular mechanism and genetic rules of coronatine regulating maize lodging resistance, which will have an important reference value for the lodging resistance of maize breeding and chemical regulation of plant shape to increase the loding resistance of maize stems.

在玉米栽培措施中，化学调控是构建理想群体、增强玉米抗倒伏的最可行手段之一。冠菌素作为一种新型植物激素，它能够调控植物生长、增加细胞壁的厚度，提高植物抗逆性。本研究以RIL群体、B73玉米自交系、定向突变了玉米编码木葡聚糖-内切转糖基酶基因的突变体及过表达植株为研究对象。我们拟研究在玉米拔节期叶面喷施冠菌素对茎秆表观性状、细胞壁的微观结构、木质素和纤维素的积累及调控细胞壁合成过程中关键酶活性及相关基因表达的影响。同时，我们研究RIL群体中各家系茎秆抗倒伏相关性状的表型调控、联合方差分析及多世代联合分离分析方法研究冠菌素调控茎秆强度相关基因的QTL定位；旨在解析冠菌素调控玉米茎秆抗倒伏的分子机理及遗传规律，这将为玉米的抗倒伏育种及化学调控株型提供有效参考。

玉米的高产通常是通过增加种植密度来实现。但随着玉米密度的增加，茎秆质量减弱，倒伏风险增加。近年来，植物生长调节剂通过调控代谢产物生物合成和信号转导过程，降低倒伏风险，提高粮食产量。冠菌素(COR)是丁香假单胞菌(Pseudomonas)产生的一种植物毒素，其结构与茉莉酸酯(jasmonates相似，但其活性远高于茉莉酸及其甲酯。本研究旨在进一步了解冠菌素调控玉米茎秆抗倒伏的作用及其机制。以杂交品种“先玉335”(XY335)、“郑单958”(ZD958)和玉米自交系B73为材料，在大田试验和温室试验条件下，在玉米七展叶期(V7)叶面喷施不同浓度的COR。研究冠菌素对玉米秸秆的农艺性状、茎秆超微结构、内源激素含量、木质素代谢途径及木质素合成差异基因的表达。结果表明：叶面喷施10 umol L-1 COR降低株高和穗高，增加基部节间重和直径，提高穿透强度和茎秆抗弯能力。与对照相比，COR处理后通过改变激素水平、改变了次生代谢途径和氨基糖和核苷酸糖代谢途径生物合成差异表达基因，提高了茎秆发育早期木质素的积累、细胞壁的完整性和厚度，减小了茎秆单个维管束面积，优化茎秆形态特征，提高了玉米茎秆抗弯能力。