Yogendra Kalenahalli N, Dhokane Dhananjay, Kushalappa Ajjamada C, Sarmiento Felipe, Rodriguez Ernesto, Mosquera Teresa
Plant Science Department, McGill University, Ste.-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
Plant Science Department, McGill University, Ste.-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
Plant Sci. 2017 Mar;256:208-216. doi: 10.1016/j.plantsci.2016.12.014. Epub 2016 Dec 31.
The resistance to late blight is either qualitative or quantitative in nature. Quantitative resistance is durable, but challenging due to polygenic inheritance. In the present study, the diploid potato genotypes resistant and susceptible to late blight, were profiled for metabolites. Tissue specific metabolite analysis of benzylisoquinoline alkaloids (BIAs) in response to pathogen infection revealed increased accumulation of morphinone, codeine-6-glucuronide and morphine-3-glucuronides. These BIAs are antimicrobial compounds and possibly involved in cell wall reinforcement, especially through cross-linking cell wall pectins. Quantitative reverse transcription-PCR studies revealed higher expressions of TyDC, NCS, COR-2 and StWRKY8 transcription factor genes, in resistant genotypes than in susceptible genotype, following pathogen inoculation. A luciferase transient expression assay confirmed the binding of the StWRKY8 TF to promoters of downstream genes, elucidating a direct regulatory role on BIAs biosynthetic genes. Sequence analysis of StWRKY8 in potato genotypes revealed polymorphism in the WRKY DNA binding domain in the susceptible genotype, which is important for the regulatory function of this gene. A complementation assay of StWRKY8 in Arabidopsis wrky33 mutant background was associated with decreased fungal biomass. In conclusion, StWRKY8 regulates the biosynthesis of BIAs that are both antimicrobial and reinforce cell walls to contain the pathogen to initial infection.
晚疫病抗性本质上要么是定性的，要么是定量的。定量抗性具有持久性，但由于多基因遗传而具有挑战性。在本研究中，对晚疫病抗性和敏感的二倍体马铃薯基因型进行了代谢物分析。对病原体感染作出反应的苄基异喹啉生物碱（BIA）的组织特异性代谢物分析显示，吗啡酮、可待因-6-葡萄糖醛酸和吗啡-3-葡萄糖醛酸的积累增加。这些BIA是抗菌化合物，可能参与细胞壁强化，特别是通过交联细胞壁果胶。定量逆转录-聚合酶链反应研究表明，病原体接种后，抗性基因型中TyDC、NCS、COR-2和StWRKY8转录因子基因的表达高于敏感基因型。荧光素酶瞬时表达试验证实了StWRKY8转录因子与下游基因启动子的结合，阐明了其对BIA生物合成基因的直接调控作用。马铃薯基因型中StWRKY8的序列分析显示，敏感基因型中WRKY DNA结合结构域存在多态性，这对该基因的调控功能很重要。在拟南芥wrky33突变体背景下对StWRKY8进行的互补试验与真菌生物量减少有关。总之，StWRKY8调节BIA的生物合成，BIA既具有抗菌作用，又能强化细胞壁以将病原体限制在初始感染部位。
