New Saccharum hybrids in S. spontaneum cytoplasm selected with RAPD and microsatellite markers

Identification of sugarcane F1 hybrids is difficult when selections are solely based on phenotypic traits. The objective of this study was to develop Saccharum hybrids in the cytoplasm of S. spontaneum with selections based on both phenotypic traits and molecular markers. Two crosses were made between a Saccharum spontaneum clone Djatiroto, and LCP 85-384, a commercial variety (Cross 97-3144), or CP 62-258, an elite clone (Cross 97-3146). Prior to crossing, the maternal inflorescences of Djatiroto were emasculated by a 45oC hot water treatment. After germination in the greenhouse, 96 progeny from each cross were transplanted to the field. Evaluations on stalk diameter (mm), Brix, and a RAPD marker OPA-11-366 were conducted on the first-ratoon crop the following year. The OPA-11-366 marker was reproducibly amplified from both sugarcane clones, but not from Djatiroto. Fifty progeny (52.1%) from Cross 97-3144 and 36 progeny (37.5%)from CROSS 97-3146 produced the RAPD marker. Five putative F1 progeny were selected from both crosses on the basis of large stalk diameter and high Brix, and the ability to produce the RAPD marker and were assigned US numbers based on the year of selection. US99-43, US99-44, US99-45, US99-46, and US99-47 were selected from Cross 97-3144; and US99-48, US99-49, US99-50, US99-51, and US99-52 were selected from Cross 97-3146. The hybrid nature of these progeny was also verified by the presence of male-specific microsatellite markers. This is the first report on the development of Saccharum hybrids in the cytoplasm of S. spontaneum through a combination of conventional and molecular breeding approaches. Availability of these F1 hybrids will enable sugarcane breeders to explore potential contribution of S. spontaneum cytoplasm in their breeding programs.