Senescence and Cell Death in Plant Development: Chloroplast Senescence and its Regulation

AbstractNACs 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.

Download Full-text

Programmed Cell Death in Plants: Insights Into developmental and Stress-Induced Cell Death

Current Protein and Peptide Science ◽

10.2174/1389203722666211109102209 ◽

2021 ◽

Vol 22 ◽

Author(s):

Heba T. Ebeed ◽

Ahmed A. El-helely

Keyword(s):

Cell Death ◽

Programmed Cell Death ◽

Plant Development ◽

Molecular Basis ◽

Stress Conditions ◽

Similar Form ◽

Cellular Homeostasis ◽

Endogenous Factors ◽

Selective Elimination

: Programmed cell death (PCD) is a fundamental genetically controlled process in most organisms. PCD is responsible for the selective elimination of damaged or unwanted cells and organs to maintain cellular homeostasis during the organ’s development under normal conditions as well as during defense or adaptation to stressful conditions. PCD pathways have been extensively studied in animals. In plants, studies focusing on understanding the pathways of PCD have advanced significantly. However, the knowledge about the molecular basis of PCD is still very limited. Some PCD pathways that have been discovered in animals are not present in plants or found with a similar form. PCD in plants is developmentally controlled (by endogenous factors) to function in organ development and differentiations as well as environmentally induced (by exogenous stimuli) to help the plant in surviving under stress conditions. Here, we present a review of the role of PCD in plant development and explore different examples of stress-induced PCD as well as highlight the main differences between the plant and animal PCD.

Download Full-text