Molecular and physiological characterization of a natural interspecific coffee hybrid

Abstract

Natural hybridization is a common phenomenon in plants and considered to be a driving force of biodiversity and evolution. In coffee spontaneous hybridization between two different species is earlier documented. Here we investigated the morphological, molecular and physiological characteristics of a natural tetraploid interspecific coffee hybrid involving allopolyploid Coffea arabica and diploid C. excelsa species. The formation of the tetraploid hybrid was postulated on account of the production of unreduced female gametes in C. excelsa. In our findings, most morphological characters of the interspecific hybrid were found to be intermediate between the putative parental species, but the young leaf colour was found to be distinctively transgressive. Sequence-related amplified polymorphism marker analysis unequivocally supported the involvement of C. excelsa and C. arabica in hybrid formation. The gas exchange parameters, chlorophyll fluorescence parameters were compared between the hybrid and parents which revealed that the interspecific hybrid had the significantly higher substomatal CO2 concentration and non-photochemical quenching compared to parents. This tetraploid interspecific hybrid encompassing the genome of two divergent species could be of ascertainable importance in arabica coffee breeding program.