茭白（Zizania latifolia）是我国南方普遍栽培的水生蔬菜，其膨大茎是由黑粉菌（Ustilago esculenta）诱导形成的，有研究认为茎膨大与植物激素有关，但对其机制迄今仍不清楚，限制了茭白高产栽培和育种技术的发展。本项目拟利用转录组测序、细胞学和HPLC分析等技术，重点研究黑粉菌-茭白互作过程中与激素代谢相关基因的表达及其与调控茎膨大的关系；测定黑粉菌侵染后茭白植株不同生长发育时期、不同组织器官中植物激素含量, 揭示茭白茎膨大的生理基础；研究细胞胼胝质累积特点及其合成酶基因表达水平，结合测定异羟肟酸类物质含量和防卫激素（水杨酸、乙烯、茉莉酸等）的水平，明确物理屏障和多信号防卫途径在"雄茭"形成中的作用。本研究结果基本揭示茭白茎膨大和"雄茭"产生的机制，对生产上提高茭白产量、防止"雄茭"产生提供理论基础和指导，同时也对研究植物-微生物互作具有理论意义。

The swollen culm of Zizania latifolia Turcz., used as an aquatic vegetable, is induced by the infection of a basidiomycete smut fungus Ustilago esculenta, which is commonly cultivated in southern China. However, in practical cultivation, some plants often escape the fungus infection, which has been a bottleneck on the cultivation of high yield and quality and breeding program of this crop. Up to date, it is unknown that what is involved in the interplay between the fungus and the host, and how the swollen culm is triggered by the fungus. Previous studies have identified several mechanisms for host cell manipulation by microbial infection and genes involved in tumor formation in maize seedlings by U. maydis infection. In natural conditions, plants have developed multifaceted defence systems, these responses include induction of pathogenesis related genes, production of secondary metabolites as well as the reinforcement of cell walls. Induction of the basal plant defence machinery occurs upon the recognition of conserved molecules which are commonly found in a variety of microbial species, but which are absent in the host. However the direct defense mechanism employed by plant against fungal infection has not been characterized in Z. latifolia-U. esculenta system. In this study, we will reveal a complex interplay of U. esculenta with its host plant,identify genes functionally involved in swollen culm formation after comparing expression in swollen culm and noninfected culm tissue by using the transcriptomic analysis. Moreover, we will visualize expressional changes of distinct biological pathways and their relation to plant defence resonses.We will also reveal the role of callose in plant defence to the fungus by characterizing callose deposits in plant cell wall using histochemical staining, and assaying the expression of callose synthase genes. The level of benzoxazinoid hydroxamic acids such as 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), 6-methoxy-2-benzoxazolinone (MBOA) and benzoxazolinone (BOA), the concentration of salicylic acid (SA), jasmonic acid (JA), ethylene and abscisic acid (ABA）will be determined to undestand whether they play a role in the mechanism of plant defence to the fungus. Based on the data obtained, the results will provide molecular evidence that U. esculenta has the capacity to extend the undifferentiated state of infected tissue and yields insight into putative defense responses as well as distinct regulatory programs triggered during U. esculenta infection.This study may unravel the complex interactions of Z. latifolia- U. esculenta, and this may be helpful in decreasing the occurrence of no swelling plant of Z. latifolia crop, which is due to the plant defence to the fungus infection, this will lay a foundation for the rational design of crop cultivation strategies for high yield and quality of this vegetable,and is also of significance in studying the plant-microbe interatctions.