Institute of Crops, Wuhan Academy of Agricultural Sciences, Wuhan, 430065, Hubei, China.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
Planta. 2021 Jan 18;253(2):34. doi: 10.1007/s00425-020-03556-2.
BnPGIPs interacted with Sclerotinia sclerotiorum PGs to improve rapeseed SSR resistance at different levels; the BnPGIP-overexpression lines did not affect plant morphology or seed quality traits. Plant polygalacturonase-inhibiting proteins (PGIPs) play a crucial role in plant defence against phytopathogenic fungi by inhibiting fungal polygalacturonase (PG) activity. We overexpressed BnPGIP2, BnPGIP5, and BnPGIP10 genes in an inbred line 7492 of rapeseed (Brassica napus). Compared with 7492WT, the overexpression of BnPGIP2 lines significantly increased Sclerotinia sclerotiorum resistance in both seedlings and adult plants. BnPGIP5 overexpression lines exhibited decreased S. sclerotiorum disease symptoms in seedlings only, whereas BnPGIP10 overexpression lines did not improve Sclerotinia resistance for seedlings or adult plants. Quantitative real-time PCR analysis of S. sclerotiorum PG1, SsPG3, SsPG5, and SsPG6 genes in overexpressing BnPGIP lines showed that these pathogenic genes in the Sclerotinia resistance transgenic lines exhibited low expression in stem tissues. Split-luciferase complementation experiments confirmed the following: BnPGIP2 interacts with SsPG1 and SsPG6 but not with SsPG3 or SsPG5; BnPGIP5 interacts with SsPG3 and SsPG6 but not with SsPG1 or SsPG5; and BnPGIP10 interacts with SsPG1 but not SsPG3, SsPG5, or SsPG6. Leaf crude protein extracts from BnPGIP2 and BnPGIP5 transgenic lines displayed high inhibitory activity against the SsPG crude protein. BnPGIP-overexpression lines with Sclerotinia resistance displayed a lower accumulation of HO and higher expression of the HO-removing gene BnAPX (ascorbate peroxidase) than 7492WT, as well as elevated expression of defence response genes including jasmonic acid/ethylene and salicylic acid pathways after S. sclerotiorum infection. The plants overexpressing BnPGIP exhibited no difference in either agronomic traits or grain yield from 7492WT. This study provides potential target genes for developing S. sclerotiorum resistance in rapeseed.
油菜 BnPGIPs 与核盘菌 PG 相互作用，以不同水平提高油菜 SSR 抗性；BnPGIP 过表达系不影响植物形态或种子质量性状。植物多聚半乳糖醛酸酶抑制蛋白（PGIPs）通过抑制真菌多聚半乳糖醛酸酶（PG）活性在植物防御植物病原真菌中发挥重要作用。我们在油菜自交系 7492 中过表达了 BnPGIP2、BnPGIP5 和 BnPGIP10 基因。与 7492WT 相比，BnPGIP2 过表达系在幼苗和成株期均显著提高了对核盘菌的抗性。BnPGIP5 过表达系仅在幼苗中表现出核盘菌病症状减轻，而 BnPGIP10 过表达系对幼苗和成株期的核盘菌抗性没有改善。过表达 BnPGIP 系中 S. sclerotiorum PG1、SsPG3、SsPG5 和 SsPG6 基因的定量实时 PCR 分析表明，这些抗生性转基因系的茎组织中这些致病基因表达水平较低。分裂萤光素酶互补实验证实：BnPGIP2 与 SsPG1 和 SsPG6 相互作用，但不与 SsPG3 或 SsPG5 相互作用；BnPGIP5 与 SsPG3 和 SsPG6 相互作用，但不与 SsPG1 或 SsPG5 相互作用；BnPGIP10 与 SsPG1 相互作用，但不与 SsPG3、SsPG5 或 SsPG6 相互作用。BnPGIP2 和 BnPGIP5 转基因系的叶片粗蛋白提取物对 SsPG 粗蛋白表现出高抑制活性。与 7492WT 相比，具有核盘菌抗性的 BnPGIP 过表达系 HO 的积累较低，HO 清除基因 BnAPX（抗坏血酸过氧化物酶）的表达较高，茉莉酸/乙烯和水杨酸途径的防御反应基因表达升高，感染核盘菌后。过表达 BnPGIP 的植株在农艺性状或籽粒产量方面与 7492WT 无差异。本研究为油菜核盘菌抗性的开发提供了潜在的靶基因。
