|Plants have acquired the ability to prime their genomes after environmental stress, enabling a faster and stronger response to future environmental cues. This is most immediately tangible for long-lived crops such as grapevine. DNA methylation is an epigenetic mechanism by which plants control their responses to stress. Such epigenetic memory could be used for breeding purposes. We used MC-Seq to determine the genomic regions showing DNA methylation changes in grapevines during/after heat, drought and combined heat/drought stress. A total of 13,968 genes were identified as differentially methylated between control and stressed plants. The methylation status of 233 of these genes was maintained after physiological recovery and was deemed to reflect epigenetic memory of stress|
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This project used genetic manipulation of grapevines as a proof of concept to improve the tannin composition of winegrapes. The efficiency of the system for producing transgenic grapevines was significantly improved and used to alter expression of three key genes of the tannin synthesis pathway. This resulted in altered tannin content and composition in leaves and grapes from the transgenic grapevines. Depending on the gene targeted, the tannin composition was selectively altered in skins or seeds of the berries. Micro-scale fermentation of grapes from the transgenic vines was used to assess the impact on wine colour and tannin.
Enhanced varieties and clones to meet the challenges of climate change and deliver lower alcohol wines
Wine grape varieties originating from a diverse range of countries and regions, and advanced CSIRO breeding lines, have been assessed. The results demonstrate that there are significant opportunities to broaden the genetic base of varieties available to the Australian industry to enhance its capability to meet the challenges associated with climate change, limited water supply and drought and high alcohol content. Specifically, varieties have been identified with short seasonality to improve water use efficiency; small canopies to minimise transpiration and improve water use efficiency; long seasonality to ripen in cooler conditions; optimal pH and titratable acidity and unique aroma and flavour profiles
Dr Ian Dry was an invited speaker at the 11th International Conference on Grapevine Breeding and Genetics, Yanqing county, Beijing 29 July - 2 August 2014 where he presented a plenary talk entitled 'Resistance strategies of grapevines to biotrophic pathogens'. This presentation gave an overview of our current knowledge regarding the identification and function of resistance genes from wild grapevine species which can be used to confer resistance to powdery and downy mildew which are the two major pathogens of cultivated grapevines. Dr Dry also took the opportunity to visit with collaborators at China Agricultural University in Beijing to discuss current and future collaborations.
The aims of this travel were:
- to participate to the XXIII Plant and Animal Genome Congress from January 10th to 14th at San Diego, USA.
- to present the Poster "We prefer them old: Epigenetic control of wine quality in response to grapevine age".
- to visit the Modesto Wine research station (Gallo Winery).
- present results on our project "Epigenetic control of wine quality in response to grapevine age" to Dr Nick Dokoozlian, responsible for research and innovation in the areas of grape and wine production at Gallo Winery).
Attendance at the 11th International Conference on Grapevine Breeding and Genetics to present research and research lab visits
The travel described I this report allowed me attend the 11th International Conference on Grapevine Breeding and Genetics. At the conference I gave a presentation on my PhD research and met with scientists from around the world who are working in the areas of grapevine breeding and genetics.
This project was successful in using advanced genetic approaches for both strategic and applied grapevine research. The methods developed resulted in the creation of a mutagenized grapevine population for gene function studies and the discovery and linking of DNA markers to key agronomic and berry traits. Crucial to the success of the project was the use of microvine material that flowered quickly and had a short generation time. The DNA markers were further developed and used to determine if marker-assisted selection (MAS) was possible for speeding up the process of producing new grapevine varieties. Over 8,000 young grapevine seedlings in a glasshouse were screened with DNA markers for mildew resistance, flower sex and
berry colour and over 1,200 that passed the DNA screen were planted in the field for evaluation. The DNA markers accurately predicted the phenotype of the plants in the field. This first generation of powdery and downy mildew resistant selections displayed no evidence of mildew in the field in a no-spray vineyard. To identify elite selections within the 1,200 vines, assessment of agronomic performance and berry and wine attributes was initiated with both white and red selections found to have variation in yield and diverse wine flavours.
Functional characterisation of transgenic winegrape varieties containing the MrRUN1 powdery mildew resistance gene and the MrRPV1 downy mildew gene from M. rotundifolia demonstrated that these genes confer strong resistance to mildew isolates from Australia, Europe and North America. However, a powdery mildew isolate from SE USA was identified which can break MrRUN1 resistance. New sources of genetic resistance to powdery and downy mildew from other North American and Chinese Vitis species were identified which could ultimately be combined with MrRUN1 and MrRPV1, in the same grapevine variety, to enhance the durability of this resistance in the vineyard.
Investigating the role of the regulatory gene VvMYBA1 in flavour and aroma using transgenic grapevines
Anthocyanins are flavonoid compounds responsible for most of the red, purple and blue colours of leaves, fruit and flowers of many plant species. They are produced through the anthocyanin biosynthesis pathway and in grapevine the VvMYBA1 and VvMYBA2 transcription factors are responsible for the transcriptional activation of genes encoding enzymes required for their synthesis. White grapevine cultivars contain inactive versions of the VvMYBA1 and VvMYBA2 genes and hence cannot produce anthocyanins in berries. While much is now known about anthocyanin biosynthesis in grapevine, there are still some genes involved in anthocyanin modification and transport which have not yet been identified. In several other plant species recent research has established a link between anthocyanin biosynthesis and the synthesis of volatile aroma compounds.
CSIRO rootstock germplasm resources and grafted, replicated trials developed through co‑investment by CSIRO and Wine Australia in previous projects (CSP 99/02 and CSP 05/03) have been maintained for 2 years to underpin future rootstock research including development of new rootstock genotypes.