MicroRNA164e suppresses NAC100 transcription factor‐mediated synthesis of seed storage proteins in chickpea

Abstract

Summary Development of protein‐enriched chickpea varieties necessitates an understanding of specific genes and key regulatory circuits that govern the synthesis of seed storage proteins (SSPs). Here, we demonstrated the novel involvement of Ca‐miR164e‐CaNAC100 in regulating SSP synthesis in chickpea. Ca‐miRNA164e was significantly decreased during seed maturation, especially in high‐protein accessions. The miRNA was found to directly target the transactivation conferring C‐terminal region of a nuclear‐localized transcription factor, CaNAC100 as revealed using RNA ligase‐mediated‐rapid amplification of cDNA ends and target mimic assays. The functional role of CaNAC100 was demonstrated through seed‐specific overexpression (NACOE) resulting in significantly augmented seed protein content (SPC) consequential to increased SSP transcription. Further, NACOE lines displayed conspicuously enhanced seed weight but reduced numbers and yield. Conversely, a downregulation of CaNAC100 and SSP transcripts was evident in seed‐specific overexpression lines of Ca‐miR164e that culminated in significantly lowered SPC. CaNAC100 was additionally demonstrated to transactivate the SSP‐encoding genes by directly binding to their promoters as demonstrated using electrophoretic mobility shift and dual‐luciferase reporter assays. Taken together, our study for the first time established a distinct role of CaNAC100 in positively influencing SSP synthesis and its critical regulation by CamiR164e, thereby serving as an understanding that can be utilized for developing SPC‐rich chickpea varieties.