A GRAS‐like gene of sunflower (Helianthus annuus L.) alters the gibberellin content and axillary meristem outgrowth in transgenic Arabidopsis plants. (1st July 2015)

• Record Type: Journal Article
• Authors: Fambrini, M.; Mariotti, L.; Parlanti, S.; Salvini, M.; Pugliesi, C.; Elzenga, T.
• Is Part Of: Plant biology. Volume 17:Number 6(2015:Nov.)
• Page Start: 1123
• Page End: 1134
• Publication Date: 2015-07-01
• Subjects: Botany -- Periodicals; Plants -- genetics -- Periodicals; Plants -- growth & development -- Periodicals; Plant Proteins -- Periodicals; Gene Expression Regulation, Plant -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1111/plb.12358
• Languages: English
• ISSNs: 1435-8603

Abstract

<abstract abstract-type="main" id="plb12358-abs-0001"> <title>Abstract</title> <p>The GRAS proteins belong to a plant transcriptional regulator family that function in the regulation of plant growth and development. Despite their important roles, in sunflower only one <italic>GRAS</italic> gene (<italic>HaDella1</italic>) with the DELLA domain has been reported. Here, we provide a functional characterisation of a GRAS‐like gene from <italic>Helianthus annuus</italic> (<italic>Ha‐GRASL</italic>) lacking the DELLA motif. The <italic>Ha‐GRASL</italic> gene contains an intronless open reading frame of 1, 743 bp encoding 580 amino acids. Conserved motifs in the GRAS domain are detected, including VHIID, PFYRE, SAW and two LHR motifs. Within the VHII motif, the P‐H‐N‐D‐Q‐L residues are entirely maintained. Phylogenetic analysis reveals that Ha‐GRASL belongs to the SCARECROW LIKE4/7 (SCL4/7) subfamily of the GRAS consensus tree. Accumulation of <italic>Ha‐GRASL</italic> mRNA at the adaxial boundaries from P6/P7 leaf primordia suggests a role of <italic>Ha‐GRASL</italic> in the initiation of median and basal axillary meristems (AMs) of sunflower. When <italic>Ha‐GRASL</italic> is over‐expressed in <italic>Arabidopsis</italic> wild‐type plants, the number of lateral bolts increases differently from untransformed plants. However, <italic>Ha‐GRASL</italic> slightly affects the <italic>lateral suppressor</italic> (<italic>las‐4‐</italic>) mutation. Therefore, we hypothesise that <italic>Ha‐GRASL</italic> and <italic>LAS</italic> are not functionally equivalent. The over‐expression of <italic>Ha‐GRASL</italic> reduces metabolic flow of gibberellins (GAs) in <italic>Arabidopsis</italic> and this modification could be relevant in AM development. Phylogenetic analysis includes LAS and SCL4/7 in the same major clade, suggesting a more recent separation of these genes with respect to other GRAS members. We propose that some features of their ancestor, as well as AM initiation and outgrowth, are partially retained in both LAS and SCL4/7.</p> </abstract>