由真菌Passalorapersonata引起的晚期叶斑病(LLS)通常比早期叶斑病更具破坏性且难以控制。本研究的目的是通过鉴定宿主-病原体相互作用过程中诱导的抗性特异性生物标志物和代谢途径,破译花生基因型对人性障碍的生化防御机制。中度抗性的未感染和感染叶片的代谢组学(GPBD4和ICGV86590),在感染后5天(播种后65天)进行抗性(KDG128和RHRG06083)和易感(GG20,JL24和TMV2)基因型。使用GC-MS的非靶向代谢物分析显示总共77种代谢物,包括碳水化合物,糖醇,氨基酸,脂肪酸,多胺,酚类物质,萜烯和甾醇。偏最小二乘判别分析(PLS-DA)的投影变量重要性(VIP)测量表明,抗性和中度抗性基因型具有更高的核糖酸强度,肉桂酸,苹果酸,角鲨烯,木酮糖,半乳糖,果糖,葡萄糖,β-amyrin和对苯二酚,而敏感基因型的葡萄糖酸2-甲基肟含量较高,核糖-己糖-3-u糖和葡萄糖酸。热图分析表明,抗性基因型具有较高的β-amyrin强度,未感染苹果酸中的氢醌,角鲨烯,受感染叶片中的腐胺和2,3,4-三羟基丁酸。树状图分析进一步分离同一簇中的抗性基因型以及感染的中度抗性基因型。确定的最重要的途径是:亚油酸代谢,黄酮和黄酮醇的生物合成,角质,suberin和蜡的生物合成,戊糖和葡糖醛酸酯相互转化,淀粉和蔗糖代谢,二苯乙烯类生物合成与抗坏血酸和醛酸盐代谢。靶向代谢物分析进一步证实,抗性基因型具有较高的初级代谢物蔗糖含量,葡萄糖,果糖,苹果酸和柠檬酸。此外,抗性基因型具有较高的水杨酸含量,coumaric,ferulic,肉桂酸,没食子酸(酚酸)和山奈酚,槲皮素和儿茶素(黄酮醇)。因此,在抗性基因型中具有较高积累的代谢物可用作筛选LSS抗性种质的生物标志物。这些结果揭示了较高量的初级代谢产物导致刺激更多的次级代谢产物如酚酸的积累。黄烷醇,二苯乙烯和萜类化合物(角鲨烯和β-淀粉苷)的生物合成,最终参与针对LLS病原体的防御机制。
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Late leaf spot (LLS) caused by fungi Passalora personata is generally more destructive and difficult to control than early leaf spot. The aim of this study was to decipher biochemical defense mechanism in groundnut genotypes against P. personata by identifying resistance specific biomarkers and metabolic pathways induced during host-pathogen interaction. Metabolomics of non-infected and infected leaves of moderately resistant (GPBD4 and ICGV86590), resistant (KDG128 and RHRG06083) and susceptible (GG20, JL24 and TMV2) genotypes was carried out at 5 days after infection (65 days after sowing). Non-targeted metabolite analysis using GC-MS revealed total 77 metabolites including carbohydrates, sugar alcohols, amino acids, fatty acids, polyamines, phenolics, terpenes and sterols. Variable importance in projection (VIP) measure of partial least squares-discriminant analysis (PLS-DA) showed that resistant and moderately resistant genotypes possessed higher intensities of ribonic acid, cinnamic acid, malic acid, squalene, xylulose, galactose, fructose, glucose, β-amyrin and hydroquinone while susceptible genotypes had higher amount of gluconic acid 2-methoxime, ribo-hexose-3-ulose and gluconic acid. Heat map analysis showed that resistant genotypes had higher intensities of β-amyrin, hydroquinone in non-infected and malic acid, squalene, putrescine and 2,3,4-trihydroxybutyric acid in infected leaves. Dendrogram analysis further separated resistant genotypes in the same cluster along with infected moderately resistant genotypes. The most significant pathways identified are: linoleic acid metabolism, flavone and flavonol biosynthesis, cutin, suberin and wax biosynthesis, pentose and glucuronate interconversions, starch and sucrose metabolism, stilbenoid biosynthesis and ascorbate and aldarate metabolism. Targeted metabolite analysis further confirmed that resistant genotypes possessed higher content of primary metabolites sucrose, glucose, fructose, malic acid and citric acid. Moreover, resistant genotypes possessed higher content of salicylic, coumaric, ferulic, cinnamic, gallic acid (phenolic acids) and kaempferol, quercetin and catechin (flavonols). Thus metabolites having higher accumulation in resistant genotypes can be used as biomarkers for screening of LSS resistant germplasm. These results unravel that higher amount of primary metabolites leads to stimulate the accumulation of more amounts of secondary metabolites such as phenolic acid, flavanols, stilbenes and terpenoids (squalene and β-amyrin) biosynthesis which are ultimately involved in defense mechanism against LLS pathogen.
UNASSIGNED: The online version contains supplementary material available at 10.1007/s12298-021-00985-5.