Document Type
Thesis - Open Access
Award Date
2008
Degree Name
Doctor of Philosophy (PhD)
Department / School
Biology
Abstract
Regulation of the growth cycle in grapevine is important for crop production and vine survival. In particular, maintenance of the developing bud in paradormancy is critical for the vine to produce shoot and flower primordia for the next seasons while preventing bud outgrowth in the current season. Developing an understanding of the underlying mechanisms regulating paradormancy can contribute to better cultural management of vine canopy during the growing season; however, a systematic study of axillary bud paradormancy has not been done. The objective of this dissertation is to investigate factors influencing maintenance of axillary bud paradormancy and explore the underlying molecular mechanisms. A physiological experiment was conducted to study the interaction of apex and summer laterals on bud paradormancy in Vitis riparia vines growing in a controlled environment. Shoot tip nodes and summer lateral nodes were found to decrease the bud weight and length significantly. The further the bud was located from the shoot tip, the lower the bud fresh weight with these factors also having interaction effects on the bud weight and length. The shoot tip, summer laterals and leaves contribute to maintenance of axillary bud paradormancy in the summer. In addition, the bud position, thus its developmental stage, also influences paradormancy status. Transcriptomic analysis of active shoot apical meristems (SAM) versus SAM under correlative inhibition (paradormant buds) was conducted in V. riparia and Seyva/ grapevines using the Affymetrix VitisGeneChip to determine genes actively involved in the maintenance of bud paradormancy. The gene expression profiles of the shoot tip and axillary bud are very different. Genes with metabolic and energy functions were overrepresented in the shoot tip and transcription and metabolic functions were overrepresented in the buds. Transcripts comparison between V. riparia and Seyva/ indicated a high number of tissue specific genes were found in common to both genotypes. Based on this transcriptomic analysis, phytohormone and sugar transport related gene expression was analyzed to help define pathways and processes involved in paradormancy and growth cycling process. Three hypotheses of apical dominance were examined. Real-time RT-PCR technique was used to investigate five genes hypothesized to be involved in paradormancy regulation. Expression of PIN3, IPT, AMil, H3, and HTl was determined in the grapevine shoot tip, compound bud and summer lateral from the same position at each time point during a 3-week period of growth and development. The results suggested that the most mature buds had lower ability to produce endogenous auxin and transport auxin outside of the bud. Examination of spatially separated tissues indicated that all five genes had significant differential expression among shoot tip, buds, and summer laterals at different positions from the shoot tip. These results indicate that the current three hypotheses do not separately explain apical dominance; rather components of all of the hypotheses are combined to propose a model for grapevine apical interaction with bud paradormancy.
Library of Congress Subject Headings
Grapes -- Growth
Buds
Growth (Plants) -- Regulation
Format
application/pdf
Number of Pages
159
Publisher
South Dakota State University
Recommended Citation
He, Dong, "Exploring Mechanisms Involved in Grapevine Bud Paradormancy" (2008). Electronic Theses and Dissertations. 1443.
https://openprairie.sdstate.edu/etd2/1443
