Comparative transcriptome analysis reveals significant differences in gene expression and signalling pathways between developmental and dark/starvation‐induced senescence in Arabidopsis

Abstract

SummaryAn analysis of changes in global gene expression patterns during developmental leaf senescence in Arabidopsis has identified more than 800 genes that show a reproducible increase in transcript abundance. This extensive change illustrates the dramatic alterations in cell metabolism that underpin the developmental transition from a photosynthetically active leaf to a senescing organ which functions as a source of mobilizable nutrients. Comparison of changes in gene expression patterns during natural leaf senescence with those identified, when senescence is artificially induced in leaves induced to senesce by darkness or during sucrose starvation-induced senescence in cell suspension cultures, has shown not only similarities but also considerable differences. The data suggest that alternative pathways for essential metabolic processes such as nitrogen mobilization are used in different senescent systems. Gene expression patterns in the senescent cell suspension cultures are more similar to those for dark-induced senescence and this may be a consequence of sugar starvation in both tissues. Gene expression analysis in senescing leaves of plant lines defective in signalling pathways involving salicylic acid (SA), jasmonic acid (JA) and ethylene has shown that these three pathways are all required for expression of many genes during developmental senescence. The JA/ethylene pathways also appear to operate in regulating gene expression in dark-induced and cell suspension senescence whereas the SA pathway is not involved. The importance of the SA pathway in the senescence process is illustrated by the discovery that developmental leaf senescence, but not dark-induced senescence, is delayed in plants defective in the SA pathway.

Overexpression of a LAM Domain Containing RNA-Binding Protein LARPIc Induces Precocious Leaf Senescence in Arabidopsis

“…Microarray data showed that expression of many genes that encode RNA-binding proteins is altered during leaf senescence (Buchanan-Wollaston et al, 2005), but functional information for RNA-binding proteins involved in leaf senescence is very limited. Kim et al (2008) reported that overexpression of three hnRNP-type RNA-binding proteins (UBA2a, UBA2b, and UBA2c) induced leaf senescence and hypersensitive-like cell death.…”

“…Dramatic changes in cell structure and metabolism occur during leaf senescence, including the degradation of chloroplasts, mitochondria, and nuclei, and simultaneous catabolism of chlorophyll pigments, nucleic acids, proteins, and lipids. The nutrients released from senescing leaves are transported to newly-developing leaves, fruits, or seeds (Buchanan-Wollaston et al, 2005;Lim et al, 2007a;Munné-Bosch and Alegre, 2004).…”

“…Transcriptome analysis of senescent leaves indicated that approximately 2,500 genes (approximately 10%) in the Arabidopsis genome were expressed in senescent leaves (He et al, 2001). Microarray analysis showed that more than 800 SAGs were distinctively up-regulated during leaf senescence (Buchanan-Wollaston et al, 2005;Van Der Graaff et al, 2006). Post-transcriptional regulation plays an essential role in the regulation of gene expression during plant growth, development, and response to external stresses.…”

“…RNA-binding proteins are involved in multiple steps of post-transcriptional regulation, including pre-mRNA splicing, mRNA transport, localization, translation, and stability (Dreyfuss et al, 2002). Although many RNA-binding proteins are up-or down-regulated during leaf senescence, the biological functions of these genes are largely unknown (Buchanan-Wollaston et al, 2005;Van Der Graaff et al, 2006). Overexpression of three UBA2 genes (UBA2a, UBA2b, and UBA2c), which encode heterogeneous nuclear ribonucleoprotein (hnRNP)-type RNA-binding proteins, induce leaf senescence and hypersensitive-like cell death (Kim et al, 2008).…”

Delayed expression of SAGs correlates with longevity in CMS wheat plants compared to its fertile plants

“…GS1 and GS2 in wheat and its homologue in maize, barley and Arabidopsis showed upregulation during senescence which was associated with high grain protein (Buchanan-Wollaston et al 2005;Martin et al 2006;Goodall et al 2013). Increased mRNA levels of GS1 and GS2 may lead to higher activity of respective proteins in F plants than CMS plants which is needed for N mobilization to developing grains.…”