Speakers - AFHWC2025

Abstract

Global climate change has an impact on temperatures and water availability, leading to intense and prolonged rainfall phenomena, but also more severe drought that often compromise crop production. Although olive is a woody plant with a good adaptation to drought conditions, also this species is affected by alteration of precipitation cycles. Some olive cultivars with a greater tolerance to water stress were already selected, however the pathways involved in the tolerance response are currently still little known. To this purpose, the wide olive germplasm could help to link haplotypes cultivar-specific to characteristic of tolerance, by association the genetic variation to phenotypic variation. A SPET (Single Primer Enrichment Technology) panel of 70k target SNPs, preliminarily developed for the screening of molecular variants, produced sequencing data employed for selecting 32 genotypes obtained by propagation from cuttings and subjected to further physiological analyses.
A phenotyping protocol in a controlled environment, developed in previous study, was applied on the selected genotypes to monitor numerous parameters related to the drought stress in olive, such as Relative Water Content (RWC), chlorophyll content, gas exchange and photosynthetic efficiency.
Both WGS and SPET panel of 70k target were used to perform the association analysis by combining the genotypic dataset and the collected phenotypic parameters to detect the genomic regions associated with traits contributing to drought tolerance in olive. Variant calling allowed us to identify approximately 2.700.000 SNPs and 65.000 SNPs in WGS and SPET dataset, respectively, using as reference the genome assembly of ‘Leccino’. GWAS identified 85 significant SNPs associated with five phenotypic parameters. Notably, four SNPs showed associations with more than one monitored photosynthetic parameter, indicating a potential shared genetic basis for these traits. In particular, one of them, is located within the coding region of the gene PTEN2A which acts as both a lipid and protein phosphatase, and whose accumulation in response to salt and osmotic stresses suggests a role in the plant's response to water stress conditions.