The functional role of GM-RLK3 in soybean growth and response to biotic and abiotic stresses

Abstract

Soybean GM-RLK3 is a receptor-like kinase gene, which shares high similarity with the Arabidopsis thaliana BAM family gene suggesting a similar functional role in promoting meristem size and cell differentiation. While the functional role of RLK3 has been heavily investigated in models as well as in some agronomic crops, no studies have been conducted in soybean. The aim of this study was to examine the functional role of GM-RLK3 in soybean growth and development, in addition to assessing the response of transgenic soybean to biotic and abiotic stresses under greenhouse conditions. Stable transgenic plants for overexpression of GM-RLK3 were developed using immature cotyledon explants. Real time-PCR demonstrated the overexpression of this transgene in different tissues, and showed that GM-RLK3 was overexpressed in unifoliate tissues (52 fold increase) with lower expression in pod tissues (7.7 fold increase). Results showed that overexpression of GM-RLK3 did not improve soybean resistance to necrotrophic pathogens and abiotic stress.  Furthermore an enhanced resistance to Pseudomonas syringae pv. glycinea, as an example of biotrophic pathogens, was observed. This finding reflects activation of soybean signaling pathways involved in resistance to biotrophic pathogens. Additionally, overexpression of GM-RLK3 altered soybean growth and development by enhancing shoot biomass and number/weight of pods. Data analysis from RNA-Seq showed that overexpression of GM-RLK3 altered the transcription of other members of RLK and also of different signaling pathways involved in phosphorus, nitrogen and carbon assimilation. This study demonstrated the importance of GM-RLK3 as a regulator gene in soybean and its the overexpression provides a potential insight to improving the efficiency of soybean through manipulation of this protein.