New biotechnological approaches for a comprehensive characterization of AGL11 and its molecular mechanism underlying seedlessness trait in table grape

In table grapes seedlessness is a crucial breeding target, mainly results from stenospermocarpy, linked to the Thompson Seedless variety. Several studies investigated the genetic control of seedlessness identifying AGL11, a MADS-box transcription factor, as a crucial gene.

We performed a deep investigation of the whole AGL11 gene sequence in a collection of grapevine varieties revealing three different promoter-CDS combinations. By investigating the expression of the three AGL11 alleles and evaluating their ability to activate the promoter region, we show that AGL11 regulates its transcription in a specific promoter-CDS manner. By a multi-AGL11 co-expression analysis we identified a methyl jasmonate esterase, an indole-3-acetate beta-glucosyltransferase, and an isoflavone reductase as top AGL11 candidate targets. In vivo experiments further confirmed AGL11 role in regulating these genes, demonstrating its significant influence in seed development and thus in seedlessness trait.

The overall data allowed us to propose a novel regulatory mechanism correlating AGL11 haplotype assortment and seedlessness class, suggesting potential applications in grapevine breeding for seedlessness and fruit size optimization.

With the aim to validate in planta the proposed regulatory mechanism, we are working to stable transform ‘microvine’ plants for producing a truncated or inactivated AGL11 protein. We first demonstrated the ability of embryogenic calli, obtained from ‘microvine’ anthers collection and culture, to regenerate embryos capable of germinating and sprouting into a new plant. The use of ‘microvine’ as a model system offers promising outcomes for functional gene characterization, benefiting viticulture genetic improvement and seedless table grape cultivation.