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Title:Genetic network regulating variation in vegetative phase change in maize
Author(s):Zhang, Wei
Director of Research:Moose, Stephen P.
Doctoral Committee Chair(s):Moose, Stephen P.
Doctoral Committee Member(s):Hudson, Matthew E.; Vodkin, Lila O.; Schuler, Mary A.
Department / Program:School of Integrative Biology
Discipline:Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):vegetative phase change
leaf identity
shoot maturation
miR156
miR172
Glossy15
quantitative trait loci (QTL)
wax synthesis
Abstract:Vegetative phase change in maize is characterized by the transition from waxy juvenile leaves to pubescent, glossy adult leaves. In maize, mutants that alter the timing of vegetative phase change are valuable resources to identify the responsible factors. Also, continuous variation of leaf identity traits in diverse genetic mapping populations indicates the feasibility to use quantitative trait locus (QTL) analyses to find underlying genes. I demonstrate here that Glossy15 (Gl15) is the most important gene controlling leaf identity traits in maize. Decreased level of Gl15 mRNA in various gl15 mutant alleles promoted the transition from juvenile to adult leaf identity in all genetic backgrounds tested. Additionally, the Gl15 gene appears as the most significant QTL for leaf identity traits in multiple genetic mapping populations, where variation in both its DNA sequence and mRNA expression could explain phenotypic differences among population of diverse maize inbred lines. Building on studies of the genetic network controlling vegetative phase change in the model plant species Arabidopsis, microRNA156 (miR156) and its target the SQUAMOSA PROMOTER BINDIND LIKE PROTEIN (SPL) genes also control leaf identity traits in maize. The miR156g and SBP5 genes are found within other large-effect QTLs that controlling leaf identity traits, and the relative expression levels of these genes correlates with the timing of vegetative phase change. The unique and easily visible leaf identity traits in maize offer advantages to characterizing the effects of many other regulators as well. I found that the activities of GAs, an upstream component of the genetic network regulating vegetative phase change, promote adult leaf identity by influencing the antagonistic interactions of miR156 and miR172; whereas Gl15 conditions changes in epicuticular wax composition between juvenile and adult leaves by activating aldehyde reductase and suppressing aldehyde decarbonylase.
Issue Date:2011-01-21
URI:http://hdl.handle.net/2142/18631
Rights Information:Copyright 2010 Wei Zhang
Date Available in IDEALS:2011-01-21
2013-01-22
Date Deposited:2010-12


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