Understanding the mechanisms of the photoperiod flowering pathway in soybean
UNDERSTANDING THE MECHANISMS OF THE PHOTOPERIOD FLOWERING PATHWAY IN SOYBEAN BY WILLIAM BRIAN PRICE THESIS Submitted in partial fulfillment of the requirements for the degree of Master of Science in Crop Sciences in the Graduate College of the University of Illinois at Urbana-Champaign, 2012 Urbana, Illinois Master’s Committee: Assistant Professor Yoshie Hanzawa Professor Lila Vodkin Professor Randall Nelson Associate Professor Matthew Hudson ABSTRACT Flower transition is the shift from the vegetative phase to the reproductive phase of a plant. Flowering transition determines a plant’s survivability and reproductive success. Flowering transition is triggered by environmental and endogenous cues. The general purpose of this thesis was to gain insight into the genetics of flower transition in the major crop specie, soybean (Glycine max). Chapter One introduces the long day dicot model species Arabidopsis thaliana that serves as the paradigm of understanding the genetic basis of flower transition. The six flowering pathways of A. thaliana are described in detail to introduce the reader to the complex molecular networks that act to initiate flowering. Next, the focus narrows to advance the understanding of the photoperiodic flowering pathway. The mechanisms of photoperiod flowering in short day monocot model species Oryza sativa are introduced and described to illustrate conservation and divergence between the photoperiod flowering pathway components in the two model species. Finally, the known components of soybean photoperiod flowering are introduced, and the question is raised whether CONSTANS a known flowering promoter in Arabidopsis and rice is conserved in soybean. Chapter Two discusses the research to characterize CO homolog expression in soybean across two day length treatments by qRT-PCR through a candidate gene approach. The candidate gene approach applies bioinformatics techniques along with the recently published G. max genome to infer evolutionary history of the CO gene to identify homologs in the soybean genome for further study. Once identified, the genes can then be characterized via expression analysis to determine possible function analogous to CO. Chapter Three discusses the research to characterize CO homolog expression in soybean across two day length treatments by RNA sequencing to support the qRT-PCR results and to characterize differences in expression between seven soybean genotypes. Although the results do not provide definitive results for differences across genotypes, they do provide two putative candidates for CO-like genes that function in photoperiodic flowering pathway to induce floral initiation.
flowering, photoperiod, soybean, glycine soja, arabidopsis, co, constans, Pathways, oryza sativa, glycine max, arabidopsis thaliana, quantitative reverse transcriptase polymerase chain reaction (qrt-pcr), Ribonucleic acid sequencing (RNA-Seq)
University of Illinois - Urbana-Champaign
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