Abstract
Senescence affects the remobilization of nutrients and adaption of the plant to the environment. Combined stresses can result in premature senescence in plants which exist in the field. In this study, transcriptomic analysis was performed on mature leaves and leaves in three stages of premature senescence to understand the molecular mechanism. With progressive premature senescence, a declining chlorophyll (chl) content and an increasing malonaldehyde (MDA) content were observed, while plasmolysis and cell nucleus pyknosis occurred, mitochondria melted, thylakoid lamellae were dilated, starch grains in chloroplast decreased, and osmiophilic granules increased gradually. Moreover, in total 69 common differentially expressed genes (DEGs) in three stages of premature senescing leaves were found, which were significantly enriched in summarized Gene Ontology (GO) terms of membrane-bounded organelle, regulation of cellular component synthesis and metabolic and biosynthetic processes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that the plant hormone signal transduction pathway was significantly enriched. The common DEGs and four senescence-related pathways, including plant hormone signal transduction, porphyrin and chlorophyll metabolism, carotenoid biosynthesis, and regulation of autophagy were selected to be discussed further. This work aimed to provide potential genes signaling and modulating premature senescence as well as the possible dynamic network of gene expression patterns for further study.
Highlights
Senescence is the final phase of plant development, it promotes the remobilization of nutrients [1]and makes plants adapt well to the environment [2]
In this theoffour stages were chosen according to the visible symptom leaffully yellowing rate to judge thestudy, degree senescence
Senescence is an age-dependent degradation process, most of which has been well studied in Senescence is anbut age-dependent degradation process, most of which has been senescence well studiedstill in previous researches, the mechanism associated with combined stress-induced previousunclear researches, butavoid the mechanism combined stress-induced senescence still remains
Summary
Senescence is the final phase of plant development, it promotes the remobilization of nutrients [1]and makes plants adapt well to the environment [2]. As a regulated degeneration process, leaf senescence undergoes a series of degradations in cell structure and gene expression [3,4]. Many environmental stress conditions, such as dark [8], heat [9], light [10] and so on, as well as some endogenous factors [2,11], trigger premature senescence. Environmental conditions may affect plant growth and even induce premature senescence, leading to the decrease of plant yield and quality [13,14,15]. As reported by Ron Mittler [16], the most lethal stress condition for plants in Molecules 2018, 23, 2856; doi:10.3390/molecules23112856 www.mdpi.com/journal/molecules
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