Identification of resistance to red rot in interspecific and intergeneric hybrid clones of sugarcane

Abstract

The incorporation of red rot resistance in sugarcane is the foremost priority in Indian sugarcane breeding programs. An ideal parent should possess a high sucrose content, good agronomic traits, and red rot resistance. To enrich the parental pool with resistant sources having diverse backgrounds, many interspecific hybrid (ISH) clones and intergeneric hybrid (IGH) clones were identified in the previous decades from the 1960s and were utilised in the National Hybridization Programme. To further augment red rot resistance in the parental clones, we selected 27 ISH clones developed at ICAR-SBI Coimbatore and evaluated them against the prevailing Colletotrichum falcatum pathotypes in 10 locations representing major sugarcane growing regions of India. Among the clones, seven clones expressing more than 60% resistant or moderately resistant (R/MR) reactions in most locations against C. falcatum pathotypes CF06, CF07, CF08, CF09, and CF12 were identified as sources of red rot resistance. However, six clones showed more than 60% susceptible or highly susceptible (S/HS) reactions against the pathotypes across the locations. Besides Saccharum spontaneum, which is routinely used to transfer red rot resistance into sugarcane varieties, S. robustum and Erianthus arundinaceus, can also be used to introgress novel resistance genes to strengthen breeding for resistance. The multi-location testing of the clones identified resistance against major C. falcatum pathotypes in ISH/IGH clones, and such clones can be used as potential parents to obtain horizontal resistance against C. falcatum in sugarcane.