Somaclonal variation for herbicide-resistant strawberry development

Overview

Cultivated strawberry breeding is challenging due to its allo-octoploid and highly heterozygous genome, which limits traditional breeding approaches. This research program uses somaclonal variation, a technique that generates genetic mutations during tissue culture, as an alternative breeding tool for strawberry improvement. The project focuses on developing strawberry varieties resistant to three major herbicides used by growers and nurseries: 2,4-D, halosulfuron, and glyphosate. By leveraging established tissue culture protocols for major octoploid strawberry cultivars, the team generates large populations of somaclonal variants and selects clones with herbicide resistance traits.

Technical specifications

Approach and methodology:

• Established tissue culture conditions for major octoploid strawberry cultivars
• Generation of large somaclonal variant populations through tissue culture
• Herbicide screening using diluted formulations applied to plantlets
• Glyphosate (Roundup Weather Max) and 2,4-D (2,4-D Amine) diluted in sterilized distilled water
• One milliliter of diluent applied per somaclonal plantlet
• Assessment of chlorosis and wilting of foliage and crown after three weeks

Key findings from preliminary validation:

• Significant variation in glyphosate response among 149 somaclones tested
• One clone showed minimal damage with only very mild chlorosis while all others died
• 2,4-D response showed less variation across the population

Technical rationale:

• Glyphosate specifically disrupts EPSP synthase, making resistance selection more straightforward
• 2,4-D affects broad growth aspects, making it harder to obtain resistant clones with normal growth phenotypes
• Future testing will apply 2,4-D at earlier growth stages with larger populations for clearer symptom differentiation
• Halosulfuron resistance screening will follow the same methodology

Technology readiness level

The technology is at an early-to-mid stage of development. Tissue culture conditions have been established for major strawberry cultivars, and preliminary screening has demonstrated proof of concept for glyphosate resistance, with one resistant clone identified from 149 tested somaclones. The research team is refining screening protocols for 2,4-D and extending the approach to halosulfuron. Selected herbicide-resistant somaclones will be propagated in greenhouse conditions and subsequently tested under field conditions to validate performance in real-world agricultural settings.