Application of gene editing tools for the ScSPL gene and overexpression of the ScIQD gene aiming at resistance to Sporisorium scitamineum in sugarcane and energy cane

• Grant number: 25/22678-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: November 01, 2025
• End date: June 30, 2029
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Silvana Aparecida Creste Dias de Souza
• Grantee: Laísa Medeiros Rocha
• Host Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Campinas , SP, Brazil
• Associated research grant: 20/07045-3 - Biotechnological and genomic strategies for quality, productivity and sustainable management of citrus, coffee and sugar cane in the State of São Paulo, AP.NPOP

Abstract

The fungal pathogen Sporisorium scitamineum, the causal agent of sugarcane smut disease, poses a significant and widespread threat to sugarcane and energy cane cultivation. This soil-surviving fungus infects meristematic tissues, drastically altering the metabolism of susceptible plants, leading to severe symptoms like excessive tillering, decreased stalk diameter, reduced sucrose quality and yield, and the formation of the characteristic "whip" for spore dispersal. While fungicide application is an option, the development and utilization of resistant varieties is the most effective, environmentally and economically sustainable control strategy. Resistance is a quantitative trait governed by complex mechanical and biochemical defense mechanisms, making the understanding of cumulative gene effects and molecular interactions during infection critical for breeding efforts.Preliminary functional genomics analyses conducted under previous projects, using both Arabidopsis thaliana and Saccharum spp. varieties, provided key insights. Specifically, when an intermediate-resistance sugarcane variety (IACSP02-1064) was inoculated with S. scitamineum, a significant increase in the expression of the ScIQD gene (an AtIQD6 ortholog) and a significant decrease in the expression of the ScSPL gene (an AtSPL13 ortholog) were observed. IQD proteins are known to interact with calmodulin, regulating calcium signaling, microtubule dynamics, and stress responses, while SPL factors regulate growth, development, and floral induction. These findings suggest that the upregulation of ScIQD and the repression of ScSPL are associated with enhanced smut resistance in Saccharum spp.Based on these preliminary findings, this project hypothesizes that overexpressing ScIQD will enhance Sporisorium scitamineum resistance in both the intermediate-resistant sugarcane variety (IACSP02-1064) and the susceptible energy cane variety (Vértix 10). Concurrently, it is proposed that reducing or eliminating ScSPL expression will increase resistance in Vértix 10. To rigorously test this hypothesis, the project will employ two parallel genetic engineering approaches: first, the production of cisgenic plants (in both IACSP02-1064 and Vértix 10) for ScIQD overexpression using established agricultural technology; and second, the generation of ScSPL knockout plants (in Vértix 10) utilizing the innovative CRISPR/Cas12a gene editing system. The Cas12a system is highly suitable for the polyploid, complex genome of sugarcane (2n=114) due to its high specificity and low off-target rate. The resulting genetically modified plants will be inoculated with S. scitamineum and assessed for changes in physiological and molecular defense parameters. Ultimately, the project aims to functionally characterize these two genes, generate data for developing resilient varieties, and optimize advanced gene editing protocols for Saccharum spp. (AU)