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

Abstract

Leaf senescence is the final stage of leaf life history, and it can be regulated by multiple internal and external cues. La-related proteins (LARPs), which contain a well-conserved La motif (LAM) domain and normally a canonical RNA recognition motif (RRM) or noncanonical RRM-like motif, are widely present in eukaryotes. Six LARP genes (LARP1a-1c and LARP6a-6c) are present in Arabidopsis, but their biological functions have not been studied previously. In this study, we investigated the biological roles of LARP1c from the LARP1 family. Constitutive or inducible overexpression of LARP1c caused premature leaf senescence. Expression levels of several senescence-associated genes and defense-related genes were elevated upon overexpression of LARP1c. The LARP1c null mutant 1c-1 impaired ABA-, SA-, and MeJA-induced leaf senescence in detached leaves. Gene expression profiles of LARP1c showed age-dependent expression in rosette leaves. Taken together, our results suggest LARP1c is involved in regulation of leaf senescence.

Expression of potato RNA-binding proteins StUBA2a/b and StUBA2c induces hypersensitive-like cell death and early leaf senescence in Arabidopsis

“…At the molecular level, SAGs and defence-associated PR genes are upregulated with progression of senescence ( Lim et al , 2007 ). Consistently, overexpression of LARP1c or Arabidopsis UBA2s in Arabidopsis also increases the expression of SAG and PR genes ( Kim et al , 2008 ; Zhang et al , 2012 ). Leaf senescence is also triggered by plant hormones such as ethylene, jasmonic acid, ABA, and salicylic acid (SA), and can be repressed by cytokinin ( Zhang and Zhou, 2012 ).…”

“…In addition to UBA2s and StUBA2s , constitutive expression of another set of Arabidopsis RBPs, LARP1b and LARP1c, was recently reported to induce precocious leaf senescence in Arabidopsis ( Zhang et al , 2012 ). These gain-of-function mutants showed reduced chlorophyll content and hypersensitive-like cell death starting from leaves at a lower position, which is very similar to the phenotype observed in StUBA2a/b transgenic plants.…”

“…These gain-of-function mutants showed reduced chlorophyll content and hypersensitive-like cell death starting from leaves at a lower position, which is very similar to the phenotype observed in StUBA2a/b transgenic plants. Transcript level of the native LARP1c increased along with the progression of leaf senescence, and overexpression of LARP1c induced the expression of SAG12 and 13 , suggesting that LARP1c and SAGs may be involved in plant senescence concomitantly ( Zhang et al , 2012 ). Therefore, an examination of whether overexpression of StUBA2a/b or StUBA2c induced the upregulation of LARP1b and LARP1c ( Supplementary Fig.…”

“…Recent work also revealed that Arabidopsis LAM-domain RBPs, LARP1b and LARP1c, are also positive regulators of leaf senescence. Overexpression of LARP1s induced leaf senescence in Arabidopsis and elevated transcript abundance of senescence- and defence-related genes, including senescence-associated genes ( SAGs ) and pathogen-related genes ( PR s) ( Zhang et al , 2012 ). Both LARP1c and UBA2s are involved in leaf senescence seemingly as positive regulators, but they differ in subcellular localization with LARP1c found in the cytoplasm and UBA2s in the nucleus.…”

Mapping and fine-mapping of genetic factors affecting bovine milk composition

“…In viruses, the LARP1B gene has the biological process of mitophagy in response to mitochondrial depolarization (Orvedahl et al, 2011). In Arabidopsis, the overexpression of the LARP1B gene causes a premature leaf yellowing phenotype, and leaf senescence (Zhang et al, 2012).…”