Gerson Ramírez1, Claudia Echeverri-Rubiano1, Carolina Saavedra2, Jhon Henry Trujillo2, Fernando S Aguilar2 and Carolina Camargo1
1Entomology laboratory, Colombian Sugarcane Research Center – Cenicaña, Valle del Cauca, Colombia
2Biotechnology laboratory, Colombian Sugarcane Research Center – Cenicaña, Valle del Cauca, Colombia
Since its detection in 2007, the spittlebug Aeneolamia varia has increasingly threatened sugarcane production in the Cauca River Valley in Colombia. By 2021, 84% of the sugarcane area (241,169 ha) grew varieties susceptible to this pest, highlighting the need for genetic resistance studies. This study aimed to identify sugarcane genotypes with contrasting levels of damage (higher and lower than a control) to investigate potential resistance mechanisms. Data from 42 controlled trials evaluating foliar damage and spittlebug survival across 648 genotypes were analysed. To explore molecular resistance markers, 220 genotypes from the germplasm bank were used in a Genome-Wide Association Study (GWAS) based on 19,775 SNPs. Dunnett’s test identified three damage response groups relative to the susceptible control variety CC 85-92. Results showed that 21 genotypes exhibited higher damage, 620 had similar damage, and 7 showed lower damage compared to the susceptible control CC 85-92. Two genotypes, CCSP 89-342 (higher damage) and EPC 50007 (lower damage), were validated across multiple evaluations as reliable contrasts. Additionally, CC 01-1305, CC 01-1567, CC 83-08, and SP 71-1011 were identified for further study despite being evaluated in fewer trials. A notable survival rate of over 50% in A. varia suggests that tolerance may be a key resistance mechanism in the lower-damage genotypes. With GWAS, three SNP markers were identified and further validated. When searching for candidate genes in a framework of 397 kb, the Protein Detoxification 14 gene (DTX14) was identified because of its relevance in the degradation of toxic compounds produced by the insect. This study supports spittlebug management by establishing baseline susceptibility in germplasm bank varieties.