MpSNAC67 transcription factor of banana regulates stress induced senescence through salicylic acid dependent pathway

Abstract

Stress induced senescence negatively impact yield but is a crucial factor for reproductive growth and thus ensues the evolutionary success of crops. Senescence associated NAC transcription factors have been reported to control ABA-mediated senescence however, their regulation over salicylic acid (SA) mediated senescence has not been studied. Here, we report the functions of MpSNAC67 , a NAC transcription factor from banana in regulating the stress induced senescence through coordination of senescence associated genes and SA content. MpSNAC67 induces ICS1 while it suppresses SAGT1 causing reduced SA content in snac67 plants which suggest that MpSNAC67 functions through SA mediated pathways. Suppression of NCED -like and ABA3 -like in SNAC67-Oxp plants and reduced ABA content in snac67 knockout plants suggest that MpSNAC67 functions through ABA independent pathways. ROS accumulation, a function of SA-pathway was significantly diminished in snac67 plants as evident by induction of antioxidant genes in snac67 plants and suppression in SNAC67- Oxp plants. MpSNAC67 induces SA mediated senescence as evident by elevated chlorophyll-content and suppression of senescence associated genes such as ORS1 -like in snac67 plants. ORS1 -like is strongly induced under natural senescence while MpSNAC67 is not suggesting that MpSNAC67 coordinate stress-specific senescence to age dependent senescence. MpSNAC67 is induced under salinity stress, drought and exposure of SA, ABA and methyl-jasmonate suggesting MpSNAC67 coordinate different stress signals to finetune SA-mediated senescence in plants. Thus, MpSNAC67 is master regulator of stress mediated senescence in banana plants. • MpSNAC67 regulates stress induced senescence through elevation of SA content. • MpSNAC67 is induced under salinity, drought, exposure of SA, ABA and methyl-jasmonate indicating roles of MpSNAC67 in regulating different stress induced senescence in plants. • ORS1 -like but not MpSNAC67 is strongly induced under aging associated senescence indicating that MpSNAC67 coordinate stress induced senescence to age dependent senescence. • ROS level were significantly diminished in snac67 plants indicating that MpSNAC67 triggers SA dependent ROS generation during senescence.