Interested Members of the University Community are invited to attend the Final Oral Examination for the Degree of Doctor of Philosophy of Arshdeep Singh Gill of the Department of Plant Agriculture

Date: Monday, November 6, 2023
Time: 2 pm
Location: CRSC 307
Join Zoom Meeting: https://zoom.us/j/98615335254?pwd=WjNKQlEydmdFL3hJbUx4NjByYjVJZz09
Meeting ID: 986 1533 5254
Passcode: 453698

Thesis Title: Gene expression analysis of two Asparagus officinalis L. cultivars with varying levels of freezing tolerance under field and controlled environments

Advisory Committee  
Dr. David Wolyn, Advisor
Dr. Angela Canovas
Dr. Gale Bozzo
Dr. Lewis Lukens

Examination Committee
Dr. John Sulik, Chair
Dr. Bill Biligetu, External Examiner
Dr. David Wolyn
Dr. Angela Canovas
Dr. Joseph Colasanti                                 

ABSTRACT

Freezing tolerance in asparagus has been associated with timely acclimation of cultivars in the fall, delayed spring deacclimation, and levels of certain cryoprotectants such as fructans, glucose, protein, and proline in the crown. In the current study, gene expression analysis was performed using asparagus cultivars with varying adaptation to southern Ontario to uncover the molecular mechanisms involved in freezing tolerance. In the field, cultivar ‘Guelph Millennium’, adapted to southern Ontario, acclimated earlier in the fall than the unadapted cultivar, ‘UC157’ but both cultivars achieved similar levels of freezing tolerance late in the season. During the spring, UC lost its freezing tolerance earlier than GM. Differential gene expression patterns between cultivars especially in the buds were consistent with the differences and similarities in freezing tolerance. Functional analysis indicated that carbohydrate metabolism, proline metabolism, plant hormone signal transduction, biosynthesis of secondary metabolites, photosynthesis, circadian rhythm, heat shock proteins, and late embryogenesis abundant proteins may be important for fall cold acclimation and spring deacclimation and regulate freezing tolerance in asparagus.  Two C-repeat binding factor candidate genes were also highly induced in both cultivars in response to cold acclimation and shock treatments under controlled conditions. These results provide new insights into the cold acclimation and deacclimation processes in asparagus and could be valuable for the continued development of breeding or genetic engineering strategies to improve asparagus germplasm for freezing tolerance.

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