Auxin/gibberellin interactions in pea leaf morphogenesis

Abstract

Pea (Pisum sativum) has been an important model plant for several generations of plant physiologists, geneticists and developmental biologists. There exists an extensive body of knowledge on the genetics of many developmental processes including gibberellic acid (GA) biosynthesis and GA and auxin interactions during stem elongation. Auxin is a morphogen and is transported from cell to cell via vesicle‐mediated secretion from sites of synthesis. This creates auxin concentration gradients, which can regulate genes controlling morphogenesis. Among the genes regulated are those of GA biosynthesis and this subsequently sets up secondary, parallel gradients of GA concentration. Both these hormones have been proposed to play roles during leaf development in other plant species. The question posed is whether auxin/GA interactions control leaf morphogenesis in pea. It was addressed by (1) looking at effects of auxin and GA inhibitors on leaf development, (2) attempting to rescue leaf form mutants by hormone application and (3) looking for genes expressed during leaf development that might be regulated by auxin and GA. Auxin and GA inhibitors produce common abnormalities during pea leaf development of wildtype (WT) cultured plantlets, which include: inhibition of leaf initiation, reductions in the number of pinna pairs produced and conversion of terminal tendrils into leaflets. Both GA and auxin rescued the tendrilled acacia (uni‐tac) mutant by (1) increasing the number of pinna pairs produced and (2) converting terminal leaflets into tendrils. The Uni gene was transcriptionally up‐regulated by auxin in shoot tips of cultured WT plantlets. Stable mRNA levels of three genes (PsPIN1, LE and IAA 4/5) known to be auxin‐regulated also increased. These results suggest that both auxin and GA are involved in leaf initiation, promote leaf tip growth, and function in gradients and at multiple levels during pea leaf morphogenesis. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 150, 45–59.

Linking Auxin with Photosynthetic Rate via Leaf Venation

“…5A). In wild-type plants, high auxin activity in vascular tissue of developing leaves has been reported previously in pea (Demason et al, 2013) as well as Arabidopsis (Mattsson et al, 2003); in crd-4 leaves we found no GUS staining apparent in the developing veins (Fig. 5A).…”

Gene expression profiling of Jack Pine (Pinus banksiana) under copper stress: Identification of genes associated with copper resistance

“…Excess copper can deregulate auxin homeostasis and distribution which can negatively impact various aspects of plant development [ 103 , 104 ]. In particular, the deregulation of auxin can affect cell division, cell elongation, leaf morphogenesis, and hormone crosstalk, [ 103 , 105 , 106 ]. In response to copper stress, the downregulation of WAT1 could be a strategy to safeguard growth by altering the transport and intracellular distribution of auxin.…”

Quantitative Trait Loci Controlling Lodging Resistance and other Important Agronomic Traits in Dry Field Peas

“…A strong QTL, hereafter designated as QTL I‐1, was detected every site year on the distal region of LG I, centered around the Afila gene ( Af ), which controls leaf morphology. The af allele increases tendril number and vigor by influencing auxin concentrations in the pea plant (DeMason and Chawla, 2004; DeMason and Chawla, 2006). The semi‐leafless ( af ) allele derived from the Delta cultivar was associated or putatively associated with increased lodging resistance, decreased main stem diameter, decreased compressed main stem diameter, decreased branch diameter, decreased compressed branch diameter, decreased epicotyl diameter, and decreased yield.…”