Overexpression of AHL9 accelerates leaf senescence in Arabidopsis thaliana

Abstract

Background Leaf senescence, the final stage of leaf growth and development, is regulated by numerous internal factors and environmental cues. Ethylene is one of the key senescence related hormones, but the underlying molecular mechanism of ethylene-induced leaf senescence remains poorly understood. Results In this study, we identified one AT-hook like (AHL) protein, AHL9, as a positive regulator of leaf senescence in Arabidopsis thaliana. Overexpression of AHL9 significantly accelerates age-related leaf senescence and promotes dark-induced leaf chlorosis. The early senescence phenotype observed in AHL9 overexpressing lines is inhibited by the ethylene biosynthesis inhibitor aminooxyacetic acid suggesting the involvement of ethylene in the AHL9-associated senescence. RNA-seq and quantitative reverse transcription PCR (qRT-PCR) data identified numerous senescence-associated genes differentially expressed in leaves of AHL9 overexpressing transgenic plants. Conclusions Our investigation demonstrates that AHL9 functions in accelerating the leaf senescence process via ethylene synthesis or signalling.

Dissection of AT-Hook Motif Nuclear-Localized Genes and Their Potential Functions in Peach Growth and Development

“…The PPC domain in Type_I PpAHLs lacks the less-conserved sequence Leu-Arg-Ser-His, and this domain in Type_II and Type_III PpAHLs lacks the less-conserved sequence Phe-Thr-Pro-His (Figures S1-S3). This structure of PpAHLs in peach is consistent with the evolutionary relationship described above, in which the PPC domain is already present in ancient PpAHLs and the addition of one or more AThook motif(s) in flowering plants diversifies AHLs [7,43].…”

“…All AHL amino acid sequences were aligned using MAFFT v7 in PhyloSuite (https:// dongzhang0725.github.io/, accessed on 15 June 2023) [34]. The 10,000 bootstrap replicates and 1000 SH-aLRT random addition replicates were applied to prepare this consensus to represent the phylogenetic relationships [7]. The large-scale duplication events were obtained via MicroSyn v1 [35].…”

“…The AHL family members were shown to participate in multiple physiological processes including seed development, lipid biosynthesis, flower development, the regulation of leaf senescence, the regulation of flowering time, the differentiation of vascular tissues, pollen development and fertility, hypocotyl elongation, and responses to biotic and abiotic stresses [4,5,[7][8][9][10][11][12][13][14][15][16][17]. For example, AtAHL18, as a novel modulator of root system architecture, plays an important role in root growth and development [18].…”

“…By scanning the PPC domain and AT-hook motif in the genomes, Li et al (2022) identified 371 AHLs in 20 land plant genomes [7]. However, the functions of only a few AHL genes have been studied in Arabidopsis.…”

“…The evolution of introns is related to alternative splicing and the resulting nonsense-mediated decay of mRNA transport [47], enhancement of gene expression [48], and functional diversity of coding proteins [49][50][51]. AHL genes have diversified in this form and their function has evolved following subsequent differentiation and duplication [7,41]. Introns in various organisms, including fungi, animals, and plants, can increase the expression of their genes [31,48,52].…”