Characterising physiological, biochemical, and molecular traits in Shiraz grapevines of varying vine age in Barossa Valley

Summary

Objective

This project explores the potential drought adaptation of field-based and own-rooted grapevines of two clones, SARDI 6 and SARDI 7, with identical genetics across multiple generations (or ages). The
project will monitor the 38 vines' growth stages (Modified Eichhorn-Lorenz/E-L Stages) during the 2022-23 growing season, with detailed measurements conducted at three key phenological stages: fruit set (E-L 27), véraison (E-L 35), and pre-harvest (E-L 38). The long-term adaptation potential between generations within each clone will be analysed and compared at the physiological, hydraulic, biochemical, and molecular levels. The vine performance will be assessed using the Merbein Bunch Count (MBC) system, allometry, leaf-gas exchange, vine water status and hydraulic conductance. The biochemical measurements will include leaf reactive oxygen species (ROS) detox species, and proline accumulation as indicators of grapevine response to drought stress. 

Understanding the grapevine drought adaptation mechanisms will identify superior traits induced by stress priming over decadal timescales. If specific and desirable characteristics can be inherited through cuttings, it can be helpful for breeding, which focuses on drought resistance. This grapevine epi-breeding project can be developed by examining the epigenetic markers through the generations. The epigenetic markers will benefit clonal selection and propagation to increase drought resistance characteristics through what I call ‘Epi-Marker Assisted Selection’ (eMAS). The project aligns with the Wine Australia strategic plan, especially Strategy 3, by enhancing grape and wine excellence through plant breeding and targeting desired genotypic traits (i.e. heat and drought tolerance). Furthermore, this project aligns with Strategy 4 - to mitigate the effects of climate change, such as rising temperatures and freshwater scarcity. The drought-tolerant plant materials provide similar biomass, yield quantities, and fruit quality without supplemental irrigation, merely relying on rainfall through the growing season. This sustainable approach will help growers reduce their irrigation volumes and costs without sacrificing the yield and quality of grapes.

Background

Clonal selection has been used in the Australian viticulture industry for over half a century. It aims to provide high quality grapevine material for propagation, focusing on yield and wine quality attributes. Starting in 1986, Barossa Vine Improvement selected 150 of the oldest Shiraz vineyards, which were more than 60 years of age, due to their integrity (own roots and trueness to type), good bunch composition, healthy and consistent leaf conditions, and free from virus symptoms. The updated selection process resulted in eight SARDI Heritage Shiraz that were DNA and virus tested, including SARDI 1, SARDI 3, SARDI 4, SARDI 6, SARDI 7, SARDI 8, SARDI 9, and SARDI 10.