An Unusual Spliced Variant of DELLA Protein, a Negative Regulator of Gibberellin Signaling, in Lettuce

Abstract

DELLA proteins are negative regulators of the signaling of gibberellin (GA), a phytohormone regulating plant growth. DELLA degradation is triggered by its interaction with GID1, a soluble GA receptor, in the presence of bioactive GA. We isolated cDNA from a spliced variant of LsDELLA1 mRNA in lettuce, and named it LsDELLA1sv. It was deduced that LsDELLA1sv encodes truncated LsDELLA1, which has DELLA and VHYNP motifs at the N terminus but lacks part of the C-terminal GRAS domain. The recombinant LsDELLA1sv protein interacted with both Arabidopsis GID1 and lettuce GID1s in the presence of GA. A yeast two-hybrid assay suggested that LsDELLA1sv interacted with LsDELLA1. The ratio of LsDELLA1sv to LsDELLA1 transcripts was higher in flower samples at the late reproductive stage and seed samples (dry seeds and imbibed seeds) than in the other organ samples examined. This study suggests that LsDELLA1sv is a possible modulator of GA signaling in lettuce.

Identification of a new gibberellin receptor agonist, diphegaractin, by a cell-free chemical screening system

“…In addition, root growth of AtGID1b mutant was inhibited by lower concentration of Ancymidol, an inhibitor of GA synthesis, than that of AtGID1a and AtGID1c 24 . Furthermore, lettuce was reported to have high GA sensitivity in roots 25 , and LsGID1b-1 and LsGID1b-2 were also reported to express preferentially in roots 24 , 26 . These results indicated AtGID1b, LsGID1b-1, and LsGID1b-2 contribute GA-induced root elongation.…”

Breadfruit (Artocarpus altilis) DELLA genes: gibberellin-regulated stem elongation and response to high salinity and drought

“…3) corresponds with numbers of DELLA isoforms highly expressed in these organs of other species. For examples, maize expressed two DELLA genes, d8 and d9 (Lawit et al 2010), B. napus expressed one BnRGA (Liu et al 2010), lettuce expressed two LsDELLAs (Sawada et al 2012) and Arabidopsis expressed two, RGA and GAI at high level in vegetative organs (Tyler et al 2004). The overlapping expression patterns of the two AaDELLAs suggest functional redundancy between the two DELLAs may be expected in the vegetative organs including leaves and stems.…”