Investigation
Genetic diversity analysis in germplasm collection
The wild grapevine, Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi, considered as the ancestor of the cultivated grapevine, is native from Eurasia. In Spain, natural populations of V. vinifera ssp. sylvestris can still be found along river banks. We have performed a wide search of wild grapevine populations in Spain and characterized the amount and distribution of their genetic diversity using 25 nuclear SSR loci. The genetic diversity of wild grapevine populations was similar than that observed in the cultivated group. The molecular analysis showed that cultivated germplasm and wild germplasm are genetically divergent with low level of introgression. We have identified four genetic groups, with two of them fundamentally represented among cultivated genotypes and two among wild accessions. The analyses of genetic relationships between wild and cultivated grapevines could suggest a genetic contribution of wild accessions from Spain to current Western cultivars. Currently, we are carrying out the genome sequence analysis of wild and cultivars grapevine accessions from the Iberian Peninsula.
Natural variation at quality traits in grapevine
The color is a quality trait determined by the quantity and anthocyanin profile of the berry. The biochemical analysis of these traits in wild grape accessions showed different profiles than cultivated grapevine. We have performed a RNAseq analysis to evaluate their expression patterns and associate them with their phenylpropanoid profiles. Some genes of the phenylpropanoid pathway were up-regulated in wild compared with cultivated grapevine. These results reveal a unique pattern of transcription and biosynthesis pathways regulation underlying the enological characteristics of wild grape. In addition, the expression profiles of stress-related genes showed a specific dynamic modulation during berry development in wild berries. These results yield new knowledge on the distinct chemistry and characteristics of wild berry.
Somatic mutations that affect berry skin color leading to various phenotypes have been one of the major contributors for the current diversity in cultivated grapevines. Our research on grape berry color demonstrates that in white-skinned cultivars the absence of anthocyanins is related with the insertion of the Gret1, a long retrotransposon, in the promotor region of MYBA1 gene, combined with two non-conservative mutations in the coding sequence of MYBA2 gene. Additionally, several molecular and cellular mechanisms have been described as being behind berry skin color reversions occurring on grape varieties, which is linked to the phenolic profiles, specifically with the anthocyanin profile of the cultivars and ultimately with the skin color phenotype diversity.
Exploiting the genetic diversity of the grapevine for adaptive trait
Adaptation to adverse environment is the central survival strategy of plants. As active process, adaptation requires that resources are repartitioned that otherwise would be available for growth. When humans domesticated plants for their own purposes, they selected for high yield and rapid growth which was achieved on the cost of reduced resilience (and the lost of the genetic factors underlying this resilience). Humans compensated this by creating a highly artificial environment, where the crop is cultivated under optimal conditions and environmental challenges are compensated by agricultural means including fertilization, irrigation, weeding, and chemical plant protection. Wild ancestors of crops have to survive without relying on this artificial support and therefore represent valuable resources to mine for resilience genes or alleles. For that reason, we have analyzed wild genotypes around the Mediterranean basin and we have identified natural genotypes tolerant to abiotic stress (salinity) and better quality of grape characters related to climate change such as higher acidity and resveratrol content. In other hand, in collaboration with Dr Josefina Bota we have identified natural cultivars tolerant to drought. Actually, we are performed the physiological, molecular and metabolite analyses in order to understand the mechanims that underline this adaptation for both stresses.
