A Type II Metacaspase Interacts with RPS1-K-2 in Soybean and Analysis of the Soybean Metacaspase Gene Family

摘要

Soybean suffers from the root and stem rot disease caused by the oomycete pathogen, Phytophthora sojae. A series of Rps genes confer Phytophthora resistance, and have been utilized in fighting this serious disease in soybean. Earlier we reported the cloning of the coiled coil-nucleotide binding-leucine rich repeat gene, Rps1-k-2. Here we report the identification of a type II metacaspase, Gmmc11 that interacted with the coiled-coil (CC) domain of Rps1-k-2 in vivo in yeast. The interaction was verified by conducting in vitro pull down assays in unpublished work. RNA interference of Gmmc11 in cotyledons resulted in loss of Phytophthora resistance. Gmmc11 is comprised of N-terminal p20 caspase-like subunit, a linker region and a C-terminal p10 caspase- like subunit. Gmmc11 is processed in a non- Rps1-k-specific manner following P. sojae infection, and also in response to abiotic stress. The p10 subunit interacts with the Rps1-k-2 CC domain. Gmmc11 is strongly upregulated in response to salt stress. The soybean metacaspase gene family was identified and expression data suggests that Gmmc11 is constitutively expressed throughout the plant, with highest expression in the roots, the common entry target of P. sojae pathogen attack.