Cloning and Characterization of a Receptor-Like Protein Kinase Gene Associated with Senescence

Abstract

Senescence-associated genes are up-regulated during plant senescence and many have been implicated in encoding enzymes involved in the metabolism of senescing tissues. Using the differential display technique, we identified a SAG in bean (Phaseolus vulgaris) leaf that was exclusively expressed during senescence and was designated senescence-associated receptor-like kinase (SARK). The deduced SARK polypeptide consists of a signal peptide, a leucine-rich repeat in the extracellular region, a single membrane-spanning domain, and the characteristic serine/threonine protein kinase domain. The mRNA level for SARK increased prior to the loss of chlorophyll and the decrease of chlorophyll a/b-binding protein mRNA. Detached mature bean leaves, which senesce at an accelerated rate compared with leaves on intact plants, showed a similar temporal pattern of SARK message accumulation. Light and cytokinin, which delayed the initiation of leaf senescence, also delayed SARK gene expression; in contrast, darkness and ethylene, which accelerated senescence, advanced the initial appearance of the SARK transcript. SARK protein accumulation exhibited a temporal pattern similar to that of its mRNA. A possible role for SARK in the regulation of leaf senescence was considered.

Large‐scale identification of leaf senescence‐associated genes

“…The SSH method, which has proved to be a powerful tool for the ampli®cation of non-abundant transcripts in other systems (Diatchenko et al, 1999), allowed us to identify a number of new SAGs encoding potential regulators. In addition to the two reported senescence-related receptors, senescence-associated receptor kinase (SARK; Hajouj et al, 2000) and senescence-induced receptor kinase (SIRK; Robatzek and Somssich, 2002), we revealed in our screen a cDNA clone that represents a receptor-like protein kinase (At5g48380). Other mRNAs for signal transduction components preferentially accumulated as leaves senesce are represented by the clones encoding a small GTP-binding protein (At5g47201), related to the oncogene RAS and a G protein beta subunit-like protein (At2g43770).…”

“…Total RNA was prepared according to Hajouj et al (2000) from rosette leaves. RNA was separated on 1.0% (w/v) agarose formaldehyde gels and blotted to nylon ®lters (NytranN, Schleicher and Schuell, Dassel, Germany).…”

“…Recently, a few senescence-associated regulatory genes have been identi®ed. They are predicted to encode transcription factors (Eulgem et al, 2000;Hinderhofer and Zentgraf, 2001;Robatzek and Somssich, 2002), receptors for senescence perception (Hajouj et al, 2000;Robatzek and Somssich, 2002), and components of intracellular protein traf®cking (Guterman et al, 2003). Among the genes that are upregulated during leaf senescence are several whose transcript levels accumulate also under abiotic and biotic stresses (Binyamin et al, 2000;Hanfrey et al, 1996;John et al, 1997;Quirino et al, 1999;Weaver et al, 1998).…”

Transcription Analysis of Arabidopsis Membrane Transporters and Hormone Pathways during Developmental and Induced Leaf Senescence

“…5L; Buchanan-Wollaston et al, 2005). The senescence-associated expression of AtSIRK and a close relative in bean, SARK, was noted before (Hajouj et al, 2000;Robatzek and Somssich, 2002).…”

A Novel Nuclear-Localized CCCH-Type Zinc Finger Protein, OsDOS, Is Involved in Delaying Leaf Senescence in Rice

“…In fact, several senescence-associated regulatory genes have recently been identified. They are predicted to encode transcription factors such as WRKY6 (WRKY DNA-binding protein 6; Robatzek and Somssich, 2001) and WRKY53 (Hinderhofer and Zentgraf, 2001;Miao et al, 2004) in Arabidopsis (Arabidopsis thaliana), and receptor-like kinases such as the Arabidopsis SIRK (senescence-induced receptorlike kinase; Robatzek and Somssich, 2002) and the bean (Phaseolus vulgaris) SARK (senescence-associated receptor-like kinase; Hajouj et al, 2000). However, only a very limited number of the regulators were functionally confirmed through genetic approaches to date (Woo et al, 2001;Jing et al, 2002;Miao et al, 2004).…”