摘要：NACs are plant-specific transcription factors involved in controlling plant development, stress responses, and senescence. As senescence-associated genes (SAGs), NACs integrate age- and stress-dependent pathways that converge to programmed cell death (PCD). In Arabidopsis, NAC-SAGs belong to well-characterized regulatory networks, poorly understood in soybean. Here, we interrogated the soybean genome and provided a comprehensive analysis of senescence-associated
Glycine max (Gm) NACs. To functionally examine GmNAC-SAGs, we selected
GmNAC065, a putative ortholog of Arabidopsis
ANAC083/VNI2 SAG, and the cell death-promoting
GmNAC085, an
ANAC072 SAG putative ortholog, for analyses
. Expression analysis of
GmNAC065 and
GmNAC085 in soybean demonstrated (i) these cell death-promoting
GmNACs display contrasting expression changes during age- and stress-induced senescence; (ii) they are co-expressed with functionally different gene sets involved in stress and PCD, and (iii) are differentially induced by PCD inducers. Furthermore, we demonstrated
GmNAC065 expression delays senescence in Arabidopsis, a phenotype associated with enhanced oxidative performance under multiple stresses, higher chlorophyll, carotenoid and sugar contents, and lower stress-induced PCD compared to wild-type. In contrast,
GmNAC085 accelerated stress-induced senescence, causing enhanced chlorophyll loss, ROS accumulation and cell death, decreased antioxidative system expression and activity. Accordingly, GmNAC065 and GmNAC085 targeted functionally contrasting sets of downstream
AtSAGs, further indicating that GmNAC85 and GmNAC065 regulators function inversely in developmental and environmental PCD.
