On May 19th, Current Biology publishes online the latest findings of Prof. Qiaohong Duan’s team from the College of Horticulture and Engineering, Shandong Agricultural University (SDAU). The research discovered a mechanism on how plants prevent inbreeding and promote outcrossing to maintain hybrid vigor.

This paper is entitled “FERONIA receptor kinase-regulated reactive oxygen species mediate self-incompatibility in Brassica rapa”. Doctoral candidate Lili Zhang, Associate Prof. Jiabao Huang, Doctoral candidate Shiqi Su, Dr. Xiaochun Wei, Doctoral candidate Lin Yang are co-first authors of the paper, and Prof. Qiaohong Duan, Dr. Yuxiang Yuan, Associate Prof. Jiabao Huang are co-corresponding authors. 

 Figure 1. Prof. Duan is discussing research with Associated Prof. Huang and some students

  Chinese cabbage is a representative of the Brassica family plants, in which self-incompatibility is widely utilized as a breeding tool to prevent the formation of inbreeding seeds. Previous research has demonstrated the recognition of self-pollen via binding of pollen expressed SP11/SCR ligand and the stigma expressed SRK receptor. However, how the self-pollen was rejected was still not revealed.

  During the study, Duan’s team observed that the level of reactive oxygen species (ROS) in the stigma were increased after pollination with self-pollen and this was associated with the rejection of self-pollen. However, the level of stigmatic ROS were decreased after pollination with cross-pollen, and this was associated with the growth of cross-pollen (Figure 2). The authors further demonstrated that stigmatic ROS was produced by NADPH oxidases and regulated by FERONIA receptor kinase mediated Rac/Rop signaling pathway, upon pollination with self- or cross-pollen. Their findings not only mechanistically demonstrated how self-pollen was rejected by stigmatic ROS, but also have great value for the breakdown of SI in Chinese cabbage and other crucifer family plants.

Therefore, based on their theoretical findings on the regulation of SI, Duan’s team also successfully used ROS scavengers to reduce stigmatic ROS and broke down SI in Chinese cabbage, cabbage and radish, therefore greatly promote the propagation efficiency of parental inbred lines.

This work was supported in part by Research Start-up Fund from Shandong Agricultural University, the Key Program of Shandong Province Science Foundation (ZR2020KC017), US-NSF-1147165, and UMass NIFA/USDA MAS00525. The author ORCIDs are as follows: Q.D. 0000-0001-9016-8904; J. Huang 0000-0002-5960-9414; A.Y.C. 0000-0002-7973-022X; and H.-M.W. 0000-0003-2108-3848. Prof.  Xiansheng Zhang from Shandong Agricultural University and Prof. Alice Y. Cheng, Prof. Henming Wu from the University of Massachusetts Amherst also participated in the research.

 Figure 2. Stigmatic ROS increased after self-pollination and decreased after cross-pollination