Gene expression changes occurring at bolting time are associated with leaf senescence in Arabidopsis

Abstract

In plants, the vegetative to reproductive phase transition (termed bolting in Arabidopsis) generally precedes age‐dependent leaf senescence (LS). Many studies describe a temporal link between bolting time and LS, as plants that bolt early, senesce early, and plants that bolt late, senesce late. The molecular mechanisms underlying this relationship are unknown and are potentially agriculturally important, as they may allow for the development of crops that can overcome early LS caused by stress‐related early‐phase transition. We hypothesized that leaf gene expression changes occurring in synchrony with bolting were regulating LS. ARABIDOPSIS TRITHORAX (ATX) enzymes are general methyltransferases that regulate the adult vegetative to reproductive phase transition. We generated an atx1, atx3, and atx4 (atx1,3,4) triple T‐DNA insertion mutant that displays both early bolting and early LS. This mutant was used in an RNA‐seq time‐series experiment to identify gene expression changes in rosette leaves that are likely associated with bolting. By comparing the early bolting mutant to vegetative WT plants of the same age, we were able to generate a list of differentially expressed genes (DEGs) that change expression with bolting as the plants age. We trimmed the list by intersection with publicly available WT datasets, which removed genes from our DEG list that were atx1,3,4 specific. The resulting 398 bolting‐associated genes (BAGs) are differentially expressed in a mature rosette leaf at bolting. The BAG list contains many well‐characterized LS regulators (ORE1, WRKY45, NAP, WRKY28), and GO analysis revealed enrichment for LS and LS‐related processes. These bolting‐associated LS regulators may contribute to the temporal coupling of bolting time to LS.

AtWAKL10, a Cell Wall Associated Receptor-Like Kinase, Negatively Regulates Leaf Senescence in Arabidopsis thaliana

“…WRKY22 , a target gene of WRKY53, is induced by darkness stress, while WRKY22, similar to WRKY6, exerts positive control over dark-induced senescence [ 53 , 70 ]. WRKY28 contributes to SA biosynthesis and positively regulates age- and light-mediated leaf senescence [ 71 , 72 , 73 ]. In fact, most senescence-regulating WRKYs are involved in SA-related biological processes, which further support the large overlapping of transcriptomic changes and signaling pathways between SA-mediated stresses and age-dependent leaf senescence [ 11 , 74 ].…”

Metabolome and Transcriptome Profiling Unveil the Mechanisms of Polyphenol Synthesis in the Developing Endopleura of Walnut (Juglans regia L.)

“…As shown in Figure 8 , the genes were ranked according to their weighted correlation with MYB111 (Jr02G12175), and the top 37 genes were selected from the blue module. Among these co-expressed genes, NAP (Jr06G10616) and NAC6 (Jr03G10992) are members of the NAC transcription factor family, which can positively regulate chlorophyll degradation and cell death caused by leaf senescence [ 29 ]. ATR1 (Jr07G11827) belongs to the ERF transcription factor, which encodes the cyp450 reductase involved in the metabolism of phenylpropane [ 30 ].…”

Comparative Transcriptome-Based Mining of Senescence-Related MADS, NAC, and WRKY Transcription Factors in the Rapid-Senescence Line DLS-91 of Brassica rapa

“…In general, leaf senescence comprises a series of molecular reactions involving various genes and TFs at different stages [ 52 ]. To excavate the entire set of senescence-associated genes (SAGs) in DLS-91, we assembled a comprehensive set of genes and TFs with functions related to leaf senescence in different plant species [ 1 , 4 , 48 , 51 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ], including leaf coloration, chlorophyll biosynthesis and degradation, photosystems I and II, phytohormone signal components, chromatin mediated regulation, transcription and post-transcription, translation and post-translation mediated regulators, leaf senescence and plant immunity, and genes that are upregulated and downregulated during DLS.…”

“…We further validated the expression of this gene by qRT-PCR and obtained results similar to those of the transcriptome analysis ( Figure 6 and Table S10 ). In Arabidopsis, the flowering time regulator AGL-8 is also expressed in rosette and cauline leaves [ 52 , 92 , 93 ]. Interestingly, the promoter regions of BrAGL8-1 and BrNAP/BrNAC029-2 both possess a common LRE (the GTGGC motif), and we also discovered putative NAC (AGATTCGT) and MADS-box (CCTTTTTTGG) binding sequences in the promoter regions of both genes ( Tables S12 and S13 ).…”