Transcriptomic analyses of xylem specific tissues form Fusarium infected chickpea roots

Fusarium wilt is the most destructive soil-borne disease that poses a major threat to chickpea production. Plant resistance towards Fusarium wilt is a very complex phenomenon. In a compatible interaction, the main interface between the host and fungus is the root xylem vessels. The resistant plants known for early pathogen perception triggered molecular reprogramming leading to the activation of downstream defense responses for pathogen restriction. To comprehensively understand the interaction between Fusarium oxysporum and chickpea, the xylem-specific transcriptome analysis of wilt-susceptible (JG62) and wilt-resistant (WR315) genotypes at an early time point was investigated. Differential expression analysis showed that 1,368 and 348 DEGs responded to pathogen infection in resistant and susceptible genotypes, respectively. Transcriptional reprogramming in response to Foc2 was detected in both genotypes but the responses were more drastic in WR315 as compared to JG62. KEGG pathway analysis revealed that metabolic pathways, biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, plant hormone signal transduction and carbon metabolism were enriched in both the genotypes under Fusarium wilt. Genes associated with defense-related metabolites synthesis such as thaumatin-like protein 1b, cysteine-rich receptor-like protein kinases, MLP-like proteins, polygalacturonase inhibitor 2-like, ethylene-responsive transcription factors, glycine-rich cell wall structural protein-like, beta-galactosidase like, subtilisin-like protease, thioredoxin-like protein, chitin elicitor receptor kinase-like, proline transporter-like, non-specific lipid transfer protein and sugar transporter were mostly up-regulated in resistant as compared to susceptible genotypes. This study's result may contribute to identifying disease resistance genes, which would help in understanding the Foc resistance mechanism in chickpea

镰孢菌枯萎病（Fusarium wilt）是极具破坏性的土传病害，对鹰嘴豆（chickpea）生产构成严重威胁。植株对镰孢菌枯萎病的抗性是一种极为复杂的生物学现象。在亲和互作中，宿主与病原菌的主要互作界面为根部木质部导管。抗性植株可通过早期感知病原菌，触发分子重编程过程，进而激活下游防御应答以限制病原菌侵染。为全面解析尖孢镰孢菌（Fusarium oxysporum）与鹰嘴豆的互作机制，本研究针对两个基因型——感病材料JG62与抗病材料WR315——在早期侵染时间点开展了木质部特异性转录组分析。差异表达基因（Differentially Expressed Genes, DEGs）分析结果显示，抗病与感病基因型中分别存在1368个和348个响应病原菌侵染的DEGs。两个基因型中均检测到响应Foc2的转录重编程现象，但WR315的应答幅度远高于JG62。京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路富集分析显示，在镰孢菌枯萎病胁迫下，两个基因型均富集到代谢通路、次生代谢产物生物合成、苯丙烷类生物合成、植物激素信号转导以及碳代谢等通路。与防御相关代谢物合成相关的基因，例如类甜蛋白1b、富半胱氨酸类受体蛋白激酶、MLP样蛋白、多聚半乳糖醛酸酶抑制蛋白2样、乙烯响应转录因子、富含甘氨酸细胞壁结构蛋白样、β-半乳糖苷酶样、枯草杆菌蛋白酶样蛋白酶、硫氧还蛋白样蛋白、几丁质激发子受体激酶样、脯氨酸转运蛋白样、非特异性脂质转运蛋白以及糖转运蛋白，在抗病基因型中的上调表达水平显著高于感病基因型。本研究结果可为抗病基因的筛选提供理论参考，有助于解析鹰嘴豆抗尖孢镰孢菌的分子机制。