Somatic variants for seed and fruit set in grapevine.

Area of Science:

• Plant reproductive biology
• Viticulture genetics

Background:

• Grapevine reproductive development significantly impacts yield and quality traits such as seedlessness and berry size.
• Seasonal climate variations pose challenges to grape production, necessitating a deeper understanding of reproductive processes.

Purpose of the Study:

• To investigate grapevine clones with contrasting seed content for new insights into reproductive mechanisms.
• To characterize seed and fruit set in seedless variants and their relationship with pollination.

Main Methods:

• Genotyping using GrapeReSeq_Illumina_20K_SNP_chip and microsatellites.
• Multi-year observations of seed and fruit set under different pollination treatments.
• Transcriptomic analysis to identify genetic variations.

Main Results:

• Identified eight variant pairs differing in seed characteristics but with identical genotypes.
• Corinto Nero exhibited pollen germination failure and produced mostly seedless berries, suggesting parthenocarpy.
• Found unreduced gametes in Corinto Nero and occasional normal-like seeds in pollenless fruits across three genotypes.

Conclusions:

• Corinto Nero's seedlessness is likely due to pollen and/or embryo sac defects, possibly arising from meiotic anomalies.
• Identified single nucleotide polymorphisms between Sangiovese and Corinto Nero as potential traceability markers and functional candidates for seedlessness.