The use of mutagenesis to generate variation: A case study in Pinot gris

Abstract

Genetic variation is the cornerstone of plant breeding. In traditional grapevine cultivars, intra-varietal diversity has declined due todecades of selection for elite genotypes, shifting breeding goals, the widespread replacement of diverse germplasm with high-performance clones, and environmental pressures. Historically, mutagenesis introduced novel genetic variation and economically relevant clones.

Buds of grafted grapevines from several traditional cultivars were irradiated with X-rays and fast neutrons. Among forty newly created clones, the long-term agronomic performance of three Pinot gris clones (1‑31 Gm, 1‑32 Gm, and 1‑33 Gm) was assessed four decadesafter their creation. Across four consecutive years, yield, pruning wood weight, and key technical juice parameters showed only minor differences between clones, as evaluated using best linear unbiased estimates. In contrast, clone 1‑31 Gm consistently exhibited higherconcentrations of macronutrients (N, P, K, Ca, Mg) in the juice compared to the other two clones. Performance was strongly influenced byenvironmental conditions, and clones differed in the stability of individual traits across years, highlighting both the sensitivity of specific traits to changing conditions and the genotypic control of climate-responsive characteristics.

Cluster morphology was quantified using a 3D-based phenotyping pipeline, providing precise measurements of cluster compactness and shape. All three clones displayed a relatively loose cluster architecture.

The subtle yet meaningful differences in performance of the three clones tested offer growers the opportunity to select plant material tailored to production goals and to manage challenges such as Botrytis bunch rot under warmer, faster- ripening seasons. This highlightsthe long-term relevance of induced variation and provides insights into clone-specific performance and trait stability for informed selection in viticulture.