Autophagic Survival Precedes Programmed Cell Death in Wheat Seedlings Exposed to Drought Stress

Abstract

Although studies have shown the concomitant occurrence of autophagic and programmed cell death (PCD) in plants, the relationship between autophagy and PCD and the factors determining this relationship remain unclear. In this study, seedlings of the wheat cultivar Jimai 22 were used to examine the occurrence of autophagy and PCD during polyethylene glycol (PEG)-8000-induced drought stress. Autophagy and PCD occurred sequentially, with autophagy at a relatively early stage and PCD at a much later stage. These findings suggest that the duration of drought stress determines the occurrence of PCD following autophagy. Furthermore, the addition of 3-methyladenine (3-MA, an autophagy inhibitor) and the knockdown of autophagy-related gene 6 (ATG6) accelerated PEG-8000-induced PCD, respectively, suggesting that inhibition of autophagy also results in PCD under drought stress. Overall, these findings confirm that wheat seedlings undergo autophagic survival under mild drought stress, with subsequent PCD only under severe drought.

Comprehensive Analysis of Autophagy-Related Genes in Sweet Orange (Citrus sinensis) Highlights Their Roles in Response to Abiotic Stresses

“…In contrast, silencing of AtATG18a in Arabidopsis reduced drought and salt tolerance [25]. Knockdown of the ATG6 of wheat inhibited autophagy and resulted in accelerated programmed cell death (PCD) under drought stress [26]. Loss of ATG10 and ATG18f significantly reduced HsfA1a-induced drought tolerance and autophagosome formation in tomato [27].…”

Genome-wide analysis of autophagy-related genes in Medicago truncatula highlights their roles in seed development and response to drought stress

“…Besides changes in gene expression, the Arabidopsis autophagy-defective mutants ( atg5 , atg7 , and RNAi-ATG18a ) showed more sensitivity to drought treatment than the wild type 45 , 51 . Inhibition of autophagy by 3-MA or knockdown of ATG6 sensitized wheat seedlings to drought stress 52 . Furthermore, virus-induced gene silencing of ATG8d or ATG18h significantly reduced drought tolerance in tomato 53 .…”

Comparative transcriptomic and metabolic profiling provides insight into the mechanism by which the autophagy inhibitor 3-MA enhances salt stress sensitivity in wheat seedlings

“…These DEGs belonged to MYB, WRKY, ERF, bHLH, HBP, TCP, NAC, etc., indicating that there is a complicated transcriptional regulation network in the wheat seedling response to salt stress. All these transcription factors were identified as positive or negative regulators in the modulation of metabolic pathways under abiotic or biotic stress [ 11 , 25 , 50 ]. Some of these DEGs were more or less highly expressed in the wheat roots and leaves induced by the addition of 3-MA under salt stress.…”

“…Autophagy is a defense mechanism in plants that can be activated by salt stress [ 9 ]. Autophagy helps maintain physiological homeostasis by capturing dysfunctional or obsolete organelles and proteins in distinct double-membraned vesicles called autophagosomes and delivering these cargos to vacuoles for degradation [ 9 – 11 ]. Luo et al (2017) found that autophagy induced by salt stress was able to enhance the salt tolerance of Arabidopsis thaliana [ 12 ].…”