Mechanisms and Candidate Genes for Seed and Fruit Set in Grapevine

Abstract

Background: Grapevine reproductive development has direct implications on yield. It also impacts on berry and wine quality by affecting traits like cluster compactness, bunch and berry size, berry skin to pulp ratio or seedlessness. Seasonal fluctuations in yield, fruit composition and wine attributes, which are largely driven by climatic factors, are major challenges for worldwide table grape and wine industry. Accordingly, a better understanding of reproductive processes such as gamete development, fertilization, seed and fruit set is of paramount relevance for managing yield and quality. With the aim of providing new insights into this field, we searched for clones with contrasting seed content in two germplasm collections. Results: We identified eight variant pairs that seemingly differ only in seed-related characteristics while showing identical genotype when tested with the GrapeReSeq_Illumina_20K_SNP_chip and several microsatellites. We performed multi-year observations on fruit and seed set deriving from different pollination treatments, with special emphasis on the pair composed by Sangiovese and its seedless variant locally named Corinto Nero. The pollen of Corinto Nero failed to germinate in vitro and gave poor berry set when used to pollinate other varieties. Most berries from both open- and cross-pollinated Corinto Nero inflorescences did not contain seeds. The genetic analysis of seedlings derived from occasional Corinto Nero normal seeds revealed that the few Corinto Nero functional gametes are mostly unreduced. A number of genes potentially involved in sporogenesis and gametogenesis showed contrasting expression between Corinto Nero and Sangiovese and five missense single nucleotide polymorphisms were identified from transcriptomic data. The above findings suggest that the seedless phenotype of Corinto Nero is driven by pollen and/or embryo sac defects, and both events likely arise from meiotic anomalies. Finally, three genotypes, including Sangiovese and Corinto Nero, were unexpectedly found to develop fruits without pollen contribution and occasionally showed normal-like seeds. Conclusions: Our collective results suggest that parthenocarpy and stenospermocarpy are not restricted to Black Corinth (alias Korinthiaki) and Sultanina-derived cultivars. The single nucleotide polymorphisms identified between Sangiovese and its parthenocarpic variant Corinto Nero are suitable for testing as traceability markers for propagated material and as functional candidates for the seedless phenotype.

Dyslipidaemia and Oxidative Stress in Primary Knee Osteoarthritis: Analysis of Clinical and Serological Features

“…We compared the proportion of males and females among the three groups using the Ψ2 test. Data analysis was performed using STATISTICA (version 6.0) and GraphPad Prism (version 3.0) software [16,17].…”