Developmental Analysis of the GATA Factor Mutants in Reveals Their Roles in Nodule Formation

Formation of nodules on legume roots results from symbiosis with rhizobial bacteria. Here, we identified two GATA transcription factors, and , in , which are the homologs of () and in . Our analysis revealed that and are expressed in roots and shoots including the root tip and nodule apex. We further show that and localize to the nucleus where they interact and that single and double loss-of-function mutants of and did not show any obvious phenotype in flower development, suggesting their role is different than their closest Arabidopsis homologues. Investigation of their symbiotic phenotypes revealed that the double mutant develop twice as many nodules as wild type, revealing a novel biological role for GATA transcription factors. We found that transcript levels respond to nitrate treatment like their Arabidopsis counterparts. Global gene transcriptional analysis by RNA sequencing revealed different expression genes enriched for several pathways important for nodule development including flavonoid biosynthesis and phytohormones. In addition, further studies suggest that and are required for the expression of several genes, which they may activate directly, and many peptidase and peptidase inhibitor genes. This work expands our knowledge of the functions of in plants by revealing an unexpected role in legume nodulation.