Rice diseases are the major threat for stable rice production and food security worldwide. Deep understanding of the disease resistance pathway in rice is essential for effective control of the diseases. Although rice contains many E3 ubiquitin ligases, the function of their substrates in immune responses is still not fully understood. Recently, researchers at State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection of CAAS have published a research paper about E3 ligase SPL11 substrate protein SPIN6 in rice. 
                 
         Proposed working model of the relationship between SPL11, SPIN6, and OsRac1

They previously characterized U-box type E3 ligase SPL11 in rice that is involved in the regulation of cell death and immune responses. However, how SPL11 interacts with its substrates to control cell death and immunity is still unknown. In this paper, they found that the SPL11 interacts with SPIN6 in vitro and in vivo. SPL11 ubiquitinates SPIN6 in vitro and degrades SPIN6 in vivo via the 26S proteasome-dependent pathway. Both the Spin6 RNAi and mutant plants lead to Program Cell Death and increased resistance to the rice blast pathogen Magnaporthe oryzae and the bacterial blight pathogen Xanthomonas oryzae pv. oryzae. Importantly, they found that SPIN6 is the RhoGAP of the small GTPase OsRac1, which is a key component in rice immunity. This study provides further insights into the relationship between SPIN6 and its interacting proteins SPL11 and OsRac1, and its function in the control of cell death and immunity in rice.

More details are available on the bellow links:
http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1004629

By Yuese Ning
yuese791975@163.com