Project Number
IWBT-P 14-01
Project title
High-throughput evaluation of novel grapevine material for important traits
Project leader
Vivier, M A
Institution
University of Stellenbosch. Faculty of AgriSciences. Institute for Wine Biotechnology
Team members
Vivier, M A
Young, P R
Stander, C
Eyeghe-Bickong, H
Premsagar, V
Objectives & Rationale
The aim of this project was to screen and select potentially valuable grapevine resources in support of the industry’s current and future aims, with a specific emphasis on sustainable and environmentally friendly production. The approach was to mainly test and use in vitro or lab-based profiling phenotyping to attempt to provide alternatives or supplementary methods for classical field-based methods.
Methods
A selection of rootstock cultivars (the same cultivars being tested in a traditional rootstock trial) was selected for in vitro testing for the analyses of abiotic/biotic stress resistance phenotypes using non-field-based methods. The buds and growth points of the winter canes of the above-mentioned rootstock cultivars were used for in vitro initiation to provide source materials for in vitro grafting, as well as water and salt-stress screening. The parents and progeny of a breeding experiment (targeting disease resistance) have also been screened for a possible correlation between the waxiness of the berries and pathogen resistance. This screening occurred with berry infections with Botrytis cinerea under controlled conditions.
Key Results
All cultivars were successfully established in vitro, and large numbers of cultures were established and maintained to perform the screening for osmotic stress tolerance. A test system was implemented to evaluate the levels of stress perceived by the plantlets to compare the different materials for their stress resistance levels. Scoring of axillary bud outgrowth and the delay thereof under induced stress conditions, as well as root formation and biochemical stains
for stress indication, correlated very well with levels of stress. These methods were successful to categorise the rootstocks with regards to their known sensitivities. These methods proved to be sensitive, and since the screens are completed within 5 weeks, they hold great promise to screen materials before lengthy field trials. Towards the project’s second aim: Breeding and progeny populations screened for waxiness yielded interesting results indicating that a more waxy phenotype led to reduced infection rates when the berries were infected with B. cinerea. Strikingly, the results from an experiment where the waxes were either maintained or removed before infection showed that the wax layers were instrumental in limiting infection.
Conclusion/Discussion
This project provides experimental evidence and optimised workflows to perform in vitro/laboratory screens for simulated abiotic (like water and salt stress) and biotic (like infection stress) stresses to evaluate plant materials under controlled conditions in relatively short time frames. The methods are fairly high-throughput and the results obtained motivate that they could be very useful as pre-screening tools to evaluate large numbers of plants before embarking on field-testing of novel materials. The major benefit is potential technology/workflow optimisation that could become part of a ‘toolbox” of methods available for viticultural applications, specifically in the phenotypic characterisation of grapevine materials.