The role of winter bud dormancy in Brassica napus floral development and its genetic control

Warner, Samuel Adam Faraday (2023) The role of winter bud dormancy in Brassica napus floral development and its genetic control. Doctoral thesis, University of East Anglia.

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Abstract

Winter annuals are grown for their high yield and require vernalisation to promote spring flowering. However, winter type Brassica napus undergoes the floral transition during autumn before flowering in spring. Here, I show that following autumnal floral transition winter-type B. napus requires chilling to promote floral development and optimal yield formation. Winter warming applied to emerging floral buds is associated with delayed budding, flowering and lower thousand grain weight of winter-type B. napus. However, the extent of this delay is dependent on genotype and crop type of B. napus. Some crop types, e.g. semi-winter and Swedes show accelerated floral development in response to winter bud warming. Here, I show that during winter warming in winter-type B. napus, genes associated with bud dormancy are upregulated in developing inflorescences, including abscisic acid signalling genes through the BRANCHED-1 dormancy module. This provides evidence that in winter type B. napus the floral delay induced by winter warming is a bud dormancy response. Using a diversity set of B. napus, I uncovered genetic variation in the control of warm winter bud dormancy and present evidence that the activation of bud dormancy is mediated through control of FLOWERING LOCUS C (FLC) genes that remain active after the floral transition. I also show that the control of flowering time both before and after the floral transition involves the FLC regulator PLANT HOMOLOGOUS TO PARAFIBROMIN (PHP) and genetic variation in PHP is associated with control of flowering time and development during chilling. As warming during winter floral development is associated with yield loss, the work here shows the importance of bud dormancy in the context of climate change and presents a genetic target for breeding climate resilient rapeseed.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	21 May 2024 08:43
Last Modified:	21 May 2024 08:43
URI:	https://ueaeprints.uea.ac.uk/id/eprint/95246
DOI:

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