Characterization of a splice variant of soybean ERECTA devoid of an intracellular kinase domain in response to shade stress

The receptor-like kinase ERECTA (ER) plays vital roles in plant adaptation under environmental stress including shade avoidance in Arabidopsis. In our previous study, we identified four ER paralogues in soybean (GmERs) that showed high similarities to Arabidopsis ER. Each GmER was predicted to generate diverse alternative splicing variants. However, whether soybean GmERs contribute to shade avoidance is unknown. Here we report our characterization of GmERs in response to shading. Promoter::GUS staining analysis shows that expression of GmER paralogous genes was differentially induced under shade stress. Further analyses show that GmERa.1 and GmERa.2 exhibit a larger distinction in length than the other GmER variants. GmERa.2 has the shortest length of amino acid with only 15 leucine-rich repeats which is the part of the extracellular domain of GmERa.1. Overexpression of GmERa.2 fully rescued the hypocotyl length, leaf area and petiole length, and the sensitivity of the hypocotyl of Arabidopsis mutant er-3 to shading, suggesting that the truncated extracellular domain of GmERa might contribute importantly to shade avoidance.