Table_1_GmDAD1, a Conserved Defender Against Cell Death 1 (DAD1) From Soybean, Positively Regulates Plant Resistance Against Phytophthora Pathogens.docx

Initially identified as a mammalian apoptosis suppressor, defender against apoptotic death 1 (DAD1) protein has conserved plant orthologs acting as negative regulators of cell death. The potential roles and action mechanisms of plant DADs in resistance against Phytophthora pathogens are still unknown. Here, we cloned GmDAD1 from soybean and performed functional dissection. GmDAD1 expression can be induced by Phytophthora sojae infection in both compatible and incompatible soybean varieties. By manipulating GmDAD1 expression in soybean hairy roots, we showed that GmDAD1 transcript accumulations are positively correlated with plant resistance levels against P. sojae. Heterologous expression of GmDAD1 in Nicotiana benthamiana enhanced its resistance to Phytophthora parasitica. NbDAD1 from N. benthamiana was shown to have similar role in conferring Phytophthora resistance. As an endoplasmic reticulum (ER)-localized protein, GmDAD1 was demonstrated to be involved in ER stress signaling and to affect the expression of multiple defense-related genes. Taken together, our findings reveal that GmDAD1 plays a critical role in defense against Phytophthora pathogens and might participate in the ER stress signaling pathway. The defense-associated characteristic of GmDAD1 makes it a valuable working target for breeding Phytophthora resistant soybean varieties.

最初被鉴定为哺乳动物细胞凋亡抑制因子的抗凋亡蛋白1（defender against apoptotic death 1, DAD1），在植物中存在保守同源物，作为细胞死亡的负调控因子行使功能。目前，植物DAD家族在抵御疫霉属（Phytophthora）病原菌过程中的潜在功能与作用机制仍未明确。本研究从大豆中克隆得到GmDAD1基因，并对其进行了功能解析。大豆疫霉（Phytophthora sojae）侵染可在亲和与非亲和大豆品种中诱导GmDAD1的转录表达。通过调控大豆毛根中GmDAD1的表达水平，本研究发现GmDAD1的转录本积累量与大豆对大豆疫霉的抗性水平呈显著正相关。在本氏烟（Nicotiana benthamiana）中异源表达GmDAD1，可显著提升其对寄生疫霉（Phytophthora parasitica）的抗性。本氏烟内源的NbDAD1同样在赋予植株疫霉抗性方面发挥相似功能。作为定位于内质网（endoplasmic reticulum, ER）的蛋白，GmDAD1被证实参与内质网应激信号通路，并调控多个防卫相关基因的转录表达。综上，本研究结果表明GmDAD1在抵御疫霉属病原菌的防卫过程中发挥关键作用，且可能参与内质网应激信号通路。GmDAD1的防卫相关特性使其成为培育抗疫霉大豆品种的潜在优良靶标。