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Molecular Genetic Investigation into the Processes Underlying Transitions in Plant Gene Expression

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Title: Molecular Genetic Investigation into the Processes Underlying Transitions in Plant Gene Expression
Author: Minow, Mark Allan Alexander
Department: Department of Molecular and Cellular Biology
Program: Molecular and Cellular Biology
Advisor: Colasanti, Joseph
Abstract: This thesis investigates several unanswered questions about how plant transcription factors and small RNA (sRNA) mediate transitions in gene expression. Specifically, this thesis addresses three goals: i) to better understand the maize autonomous flowering pathway and to what extent it overlaps with the ancestral photoperiod flowering pathway, ii) to providing insights into how sRNA transcriptomes change during the creation of maize recombinant inbred lines (RILs) and near isogenic lines (NILs), and iii) to determine if Arabidopsis phloem derived sRNA signals can influence gene expression in the shoot apical meristem (SAM). The first research goal addresses the floral transition, a critical change in SAM gene expression, that initiates reproductive growth. In maize, the transition to reproductive growth is driven by an autonomous pathway controlled by the transcription factor INDETERMINATE1 (ID1). Our RNA-sequencing revealed that ID1 influences the floral transition through a pathway distinct from that used by ancestral maize, teosinte. In pursuit of the second goal, next generation sequencing was used to examine the sRNA transcriptome of maize RILs and NILs. Genome wide, most sRNA expression were found to be co-inherited with the parental DNA. However, RIL non-parental sRNA expression patterns were also observed. These non-parental sRNA expression patterns often resembled the expression state found at the same locus in the other parent. In the NIL, many sRNA expression differences were observed over the introgressed DNA and the homologous region from the recurrent parent. However, the introgressed region had low 24nt sRNA expression, perhaps related to poor genome wide homology and past breeding history. The third goal used two synthetic systems to test phloem-to-SAM sRNA trafficking. Both systems provide evidence of phloem-to-SAM sRNA movement. Since the SAM gives rise to plant gametes, phloem-to-SAM sRNA transport provides a route for somatic sRNA to initiate heritable epigenetic transitions. Understanding the mechanisms behind these various transitions in plant gene expression will ultimately allow for the precise manipulation of traits that improve plant productivity to meet the challenges of climate change in the coming century.
Date: 2020-12
Rights: Attribution-NonCommercial-NoDerivatives 4.0 International
Related Publications: Minow, M.A.A., Ávila, L.M., Turner, K., Ponzoni, E., Mascheretti, I., Dussault, F.M., Lukens, L., Rossi, V., and Colasanti, J. 2018. Distinct gene networks modulate floral induction of autonomous maize and photoperiod-dependent teosinte. J. Exp. Bot. 69(12). doi:10.1093/jxb/ery110.
Embargoed Until: 2021-11-20

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Attribution-NonCommercial-NoDerivatives 4.0 International Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International