Bipolaris maydis causing maydis leaf blight (MLB) is an aggressive fungal pathogen of maize. The present study focused on the responses of certain defence genes in the resistant and susceptible maize inbred lines viz., SC-7 and CM 119, respectively, against MLB and symptom development in the host. Biochemical activity of the PR protein β-1, 3-glucanase and phenylalanine ammonia lyase (PAL) assay, with total chlorophyll content was recorded for both the inbred lines before and after pathogen inoculation. Gene expression was studied by quantitative polymerase chain reaction (qPCR) at different time intervals post inoculation. Differential expression pattern was observed even at the same time point in both the inbred lines. Enhanced expression of the pathogenesis related (PR) protein and phenylalanine ammonia lyase (PAL) enzyme at different time points in resistant lines indicated their association with infection stages of B. maydis and response of the resistant line against disease establishment. Down regulated gene expression of pheophytinase suggests reduced enzyme activity linked with less chlorophyll degradation in the resistant line compared to the susceptible line. This fact directly correlates with symptom development of MLB disease. The present study thus revealed that the expression of defence related genes is aligned with developmental stages of the pathogen to restrict its growth and gene expression of constitutive genes also changes differentially during the disease development in resistant and susceptible lines.

中文翻译：

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玉米双极可能感染玉米基因的表达分析并评估其在抗病性和症状发展中的作用

引起马来酸叶枯病（MLB）的双极可能是玉米的一种侵袭性真菌病原体。本研究集中于抗性和易感玉米自交系，即SC-7和CM 119中某些防御基因对宿主中MLB和症状发生的反应。PR蛋白β-的生化活性在病原体接种之前和之后，自交系均记录了1、3-葡聚糖酶和苯丙氨酸氨裂合酶（PAL）测定法，并记录了总的叶绿素含量。通过定量聚合酶链反应（qPCR）在接种后的不同时间间隔研究基因表达。即使在两个近交系中的相同时间点也观察到差异表达模式。病程相关（PR）蛋白和苯丙氨酸氨裂合酶（PAL）酶在耐药株中不同时间点的增强表达表明它们与B. maydis的感染阶段相关抵抗疾病建立的能力。脱镁叶绿素酶的基因表达下调表明与易感品系相比，抗性品系中酶活性降低，叶绿素降解较少。这个事实与MLB疾病的症状发展直接相关。因此，本研究揭示了防御相关基因的表达与病原体的发育阶段相一致，以限制其生长，并且在抗性和易感品系的疾病发展过程中，组成型基因的基因表达也有所不同。