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Don Kaplan - his legacy: Influencing teaching and research

DeMason, Darleen [1], Chawla, Rekha [1], Bai, Fang [1].

Auxin/gibberellin interactions in pea leaf morphogenesis.

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 we addressed is whether auxin/GA interactions control leaf morphogenesis in pea.It was addressed by (1) identifying 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/or GA.Auxin and GA inhibitors produce common abnormalities during pea leaf development of wildtype 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 can rescue the tendrilled-acacia (uni-tac) mutant by (1) increasing the number of pinna pairs produced and (2) converting terminal leaflets into tendrils.Different synthetic and natural auxins vary in their ability to rescue this mutant.The Uni gene is transcriptionally up-regulated by both GA and auxin in wildtype plants.Two genes important to auxin transport (PsPIN1and PsPK2) are also regulated by o­ne or both hormones.These results suggest that both auxin and GA are involved in leaf initiation, promote leaf tip growth, function in gradients and at multiple levels during pea leaf morphogenesis.

1 - University of California, Botany and Plant Sciences, Riverside, California, 92521

gibberellic acid
leaf development
Pisum sativum.

Presentation Type: Symposium
Session: 26-4
Location: Ballroom 2 (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 9:05 AM
Abstract ID:95

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