Mosaic, yellow leaf, and rust (both brown and orange rust) diseases are widespread in sugarcane-producing regions worldwide, causing considerable yield losses, sugar reduction, and economic impact. Therefore, identifying disease-resistant germplasm is crucial for breeding programs aimed at developing varieties with improved resistance. In this study, ninety-one sugarcane germplasm accessions were evaluated under field conditions using randomized complete block design with three replicates to assess resistance to mosaics and yellow leaf diseases. Molecular detection was performed for the causal viruses of mosaic and yellow leaf diseases, while accessions were screened for the presence of brown rust resistance gene Bru1 and orange rust resistance marker G1 to assess their potential rust resistance. Molecular analysis detected four viruses with the following infection rates: sugarcane mosaic virus (SCMV, 1.1%), sorghum mosaic virus (SrMV, 5.5%), sugarcane yellow leaf virus (SCYLV, 8.8%) and sugarcane streak mosaic virus (SCSMV, 96.7%). Mixed infections included SrMV + SCSMV (5.5%), SCSMV + SCYLV (8.8%), and a quadruple infection (1.1%). The Bru1 gene and G1 marker were detected in 52 and 61 accessions, respectively, with 35 accessions carrying both loci, suggesting potential dual resistance to brown and orange rust. Of the 91 accessions, 43 exhibited high to moderate resistance against mosaics, while 48 were ranged between susceptible to highly susceptible. Only six accessions displayed yellow leaf disease symptoms and tested positive for SCYLV. In contrast, Yunzhe2019-110 and Yunzhe2020-1020 were SCYLV-positive but asymptomatic, suggesting resistance to sugarcane yellow leaf disease. Notably, three accessions (Yunzhe2021-1354, Yunzhe2021-1554, and Yunzhe2021-1512) were asymptomatic and tested negative for all four viruses, demonstrating resistance to SCMV, SrMV, SCSMV, and SCYLV. Among these, Yunzhe2021-1512 also harbored both the Bru1 gene and G1 marker. The findings of this study provide valuable insights for selecting elite disease-resistant germplasm and support sustainable sugarcane improvement through integrated disease management strategies.
Kong et al. (Fri,) studied this question.