Exploring the role of the BabyBoom transcription factor in enhancing somatic embryogenic transformation efficiency for Vitis Vinifera cv. ‘Sauvignon Blanc’ : A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science with Honours

Abstract

Grapevine (Vitis vinifera) has been integral to New Zealand’s history since its introduction in 1817 and now contributes over $2 billion NZD annually through wine production. Despite its economic importance, Vitis vinifera remains a clonally propagated crop with approximately 50 cultivars available in New Zealand, of which ‘Sauvignon Blanc’ accounts for two-thirds of total production. However, this monocultural reliance renders the crop highly vulnerable to unforeseen diseases and climate change. Importation of genetic material to increase genetic diversity is restricted by stringent international laws and prohibitive costs, making genetic modification a promising alternative. Yet, traditional hormone-based tissue culture methods for genetic transformation of Vitis vinifera are inefficient, often leaving transformed cells indefinitely suspended in the callus stage. To address this, improvements in tissue culture efficiency can be achieved through transcription factor (TF) manipulation, particularly focusing on BABY BOOM (BBM). BBM has been consistently highlighted in literature as critical for facilitating somatic embryogenesis (SE) transformation. Our study supports this finding by analyzing BBM gene expression through qPCR in embryogenic callus, non-embryogenic callus, leaf, and floral tissues of ‘Sauvignon Blanc.’ Results revealed a substantial difference in BBM expression, with embryogenic callus showing a 2^-ΔΔCT value of 16,518.63, equivalent to a ~4.2 log10 fold-change compared to leaf tissue and a 1.4 log10 fold-change relative to green callus (571.09). This significant upregulation of BBM highlights its role in SE and suggests its potential as a key target for enhancing transformation efficiency in recalcitrant crops like Vitis vinifera. This study underscores the importance of TF manipulation in overcoming barriers to genetic modification and offers a pathway for improving genetic diversity and resilience in economically vital crops.