Evolutionary Developmental Biology (Evo-Devo)
Demason, Darleen , Jaganatha Chetty, Venkateswari .
Interactions between GA, auxin and UNI expression controlling shoot ontogeny and leaf morphogenesis in garden pea (Pisum sativum).
Unifoliata (UNI) is a major gene controlling the number of pinna pairs produced during leaf morphogenesis in pea. There are two mutant alleles known: uni and uni-tac. Leaves on wild type plants have 2-3 pairs of proximal leaflets, 3 pairs of distal tendrils and a terminal tendril. Leaves on uni mutants are simple, bifoliate or trifoliate. Leaves on uni-tac mutants are intermediate with 2-3 pairs of proximal leaflets, 0-1 pair of distal tendrils and a terminal leaflet. A number of gibberellic acid (GA) biosynthesis mutants are known in pea including le and nana (na). Leaves on na mutants are miniaturized and possess 2 pairs of proximal leaflets, 1-2 pairs of distal tendrils and a terminal tendril. We used genetic, hormone application, and qRT-PCR experiments to explore the interactions between GA and auxin, and UNI gene expression that control shoot ontogeny and leaf morphogenesis. The rate of leaf complexity increase during shoot ontogeny (i.e. heteroblasty) and adult leaf complexity are controlled by GA through UNI. Leaves on greenhouse grown le uni-tac and na uni-tac plants are rescued by weekly GA or auxin treatments. Shoot tips of LE uni-tac have higher UNI and class I Knox mRNA levels than shoot tips of le uni-tac and na uni-tac plants demonstrating a regulatory relationship for GA. Auxin increases UNI mRNA levels in uni-tac shoot tips as well as that of other genes including class I Knox. Therefore GA and auxin positively promote leaf dissection during morphogenesis by increasing UNI expression, which subsequently prolongs the time period during which acropetally initiated pinna pairs are formed. GA and auxin play common and supportive roles in pea leaf morphogenesis as they do in many other aspects of plant development.
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1 - University Of California, Botany And Plant Sciences, 900 University Ave., Riverside, CA, 92521, USA
2 - University of California, Botany and Plant Sciences, 1125 Batchelor Hall, Riverside, CA, 92521, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell D/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 12:00 PM