Wu Tao, Peng Chune, Li Beibei, Wu Wei, Kong Lingguang, Li Fuchuan, Chu Zhaohui, Liu Fang, Ding Xinhua
State Key Laboratory of Crop Biology, College of Plant Protection, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
College of Life Science, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
Rice (N Y). 2019 Dec 12;12(1):90. doi: 10.1186/s12284-019-0352-4.
Polygalacturonase-inhibiting proteins (PGIPs) have been shown to recognize fungal polygalacturonases (PGs), which initiate innate immunity in various plant species. Notably, the connection between rice OsPGIPs and PGs in Xanthomonas oryzae pv. oryzicola (Xoc), which causes bacterial leaf streak (BLS), remains unclear. Here, we show that OsPGIP1 was strongly induced after inoculating rice with the Xoc strain RS105. Furthermore, OsPGIP1-overexpressing (OV) and RNA interference (RNAi) rice lines increased and decreased, respectively, the resistance of rice to RS105, indicating that OsPGIP1 contributes to BLS resistance. Subsequently, we generated the unique PG mutant RS105Δpg, the virulence of which is attenuated compared to that of RS105. Surprisingly, the lesion lengths caused by RS105Δpg were similar to those caused by RS105 in the OV lines compared with wild-type ZH11 with reduced Xoc susceptibility. However, the lesion lengths caused by RS105Δpg were still significantly shorter in the OV lines than in ZH11, implying that OsPGIP1-mediated BLS resistance could respond to other virulence factors in addition to PGs. To explore the OsPGIP1-mediated resistance, RNA-seq analysis were performed and showed that many plant cell wall-associated genes and several MYB transcription factor genes were specifically expressed or more highly induced in the OV lines compared to ZH11 postinoculation with RS105. Consistent with the expression of the differentially expressed genes, the OV plants accumulated a higher content of jasmonic acid (JA) than ZH11 postinoculation with RS105, suggesting that the OsPGIP1-mediated resistance to BLS is mainly dependent on the plant cell wall-associated immunity and the JA signaling pathway.
多聚半乳糖醛酸酶抑制蛋白（PGIPs）已被证明可识别真菌多聚半乳糖醛酸酶（PGs），后者在多种植物物种中引发先天免疫。值得注意的是，水稻OsPGIPs与引起细菌性条斑病（BLS）的水稻黄单胞菌稻生致病变种（Xoc）中的PGs之间的联系仍不清楚。在此，我们表明在用Xoc菌株RS105接种水稻后，OsPGIP1被强烈诱导。此外，过表达OsPGIP1（OV）和RNA干扰（RNAi）的水稻品系分别提高和降低了水稻对RS105的抗性，表明OsPGIP1有助于抗BLS。随后，我们构建了独特的PG突变体RS105Δpg，其毒力与RS105相比有所减弱。令人惊讶的是，与Xoc易感性降低的野生型ZH11相比，RS105Δpg在OV品系中引起的病斑长度与RS105引起的相似。然而，RS105Δpg在OV品系中引起的病斑长度仍明显短于ZH11，这意味着OsPGIP1介导的抗BLS反应除了PGs外还可能对其他毒力因子起作用。为了探究OsPGIP1介导的抗性，进行了RNA测序分析，结果表明与接种RS105后的ZH11相比，许多植物细胞壁相关基因和几个MYB转录因子基因在OV品系中特异性表达或被更高程度地诱导。与差异表达基因的表达一致，接种RS105后，OV植株比ZH11积累了更高含量的茉莉酸（JA），这表明OsPGIP1介导的抗BLS主要依赖于植物细胞壁相关免疫和JA信号通路。
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