A senescence-associated gene of Arabidopsis thaliana is distinctively regulated during natural and artificially induced leaf senescence

Abstract

We have characterized the structure and expression of a senescence-associated gene (sen1) of Arabidopsis thaliana. The protein-coding region of the gene consists of 5 exons encoding 182 amino acids. The encoded peptide shows noticeable similarity to the bacterial sulfide dehydrogenase and 81% identity to the peptide encoded by the radish din1 gene. The 5'-upstream region contains sequence motifs resembling the heat-shock- and ABA-responsive elements and the TCA motif conserved among stress-inducible genes. Examination of the expression patterns of the sen1 gene under various senescing conditions along with measurements of photochemical efficiency and of chlorophyll content revealed that the sen1 gene expression is associated with Arabidopsis leaf senescence. During the normal growth phase, the gene is strongly induced in leaves at 25 days after germination when inflorescence stems are 2-3 cm high, and then the mRNA level is maintained at a comparable level in naturally senescing leaves. In addition, dark-induced senescence of detached leaves or of leaves in planta resulted in a high-level induction of the gene. Expression of the sen1 gene was also strongly induced in leaves subjected to senescence by 0.1mM abscisic acid or 1 mM ethephon treatment. The induced expression of the gene by dark treatment was not significantly repressed by treatment with 0.1 mM cytokinin or 50 mM CaCl2 which delayed loss of chlorophyll but not that of photochemical efficiency.

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

“…The ABA-responsive AtSEN1 gene is up-regulated during senescence (Supplemental Fig. 10U) as described by Oh et al (1996). The ABArepressible AtPIP1.5 and AtPIP2.6 genes (Jang et al, 2004), but also the ABA-inducible AtPIP2.2, are downregulated during senescence (Supplemental Fig.…”

“…NS expression profiles were compared with profiles induced by DIS and by DET. These treatments were established to induce senescence (Becker and Apel, 1993;Oh et al, 1996;Park et al, 1998;Weaver and Amasino, 2001). As the expression profiles in senescing leaves are influenced both by the age (position) of the rosette leaf and plant age (Zentgraf et al, 2004), the use of whole plants as a source for RNA extraction could cause dilution, distortion, or blurring of senescence-associated expression profiles.…”

“…In Arabidopsis, ABA induces expression of several SAGs. Vice versa, during senescence several genes are up-regulated that are involved in ABA synthesis, metabolism, or signaling (Oh et al, 1996;Weaver et al, 1998;He et al, 2001;Buchanan-Wollaston et al, 2005). We investigated the expression profiles of 58 ABA-biosynthesis, -metabolism, and -signaling genes (Supplemental Table XVII).…”

TheArabidopsis thalianaTCP transcription factors: A broadening horizon beyond development

“…19,60 It is well known that exogenously applied methyl jasmonate (MeJA) can accelerate leaf aging and that several JA biosynthetic genes, including LIPOXYGENASE2 (LOX2), are transiently inducible during leaf developmental senescence. 87,88 LOX2 encodes a chloroplast-localized lipoxygenase that catalyzes the conversion of a-linolenic acid (18:3) into 13(S)-hydroperoxylinolenic acid, the first dedicated step for the biosynthesis of the oxylipin JA. 89 miRJAW-controlled CIN-like TCPs directly activate LOX2 transcription to promote JA synthesis, thus redundantly contributing to leaf aging.…”

Isolation and Characterization of a Putative SENESCENCE 1 Gene from Poplar (Populus alba × P. glandulosa)

“…Heynh)에서 SENESCENCE 1 (AtSEN1) 유전자가 분리되었다 (Oh et al, 1996). AtSEN1 유전자는 자연적으로 노쇠가 진행 중 인 잎에서 높게 발현하고, 삼투 스트레스와 관련된 식물호르몬 인 ABA (abscisic acid)와 잎의 탈리를 일으키는 ethylene의 전 구체인 ethephon 처리에 의해 발현이 증가하였다.…”