Androgenic Diploids of Erianthus arundinaceus with Paternal Chloroplast and Mitochondrial Genomes in Backcross Progeny of Saccharum × Erianthus Intergeneric Hybrids

Abstract

Erianthus arundinaceus (Retz.) Jesweit is a tropical wild grass used in sugarcane (Saccharum L.) breeding for introgression of disease resistance and high cane yield traits. In the backcross (BC2) hybrids of Saccharum officinarum×E. arundinaceus and S. spontaneum×E. arundinaceus, with E. arundinaceus as pollen parent, the progeny had plants morphologically resembling E. arundinaceus. These plants were with chromosome number 2n = 60, same as that of E. arundinaceus. Through genomic in situ hybridization it was found that all the chromosomes were of E. arundinaceus. PCR-RFLP studies of the chloroplast and mitochondrial DNA polymorphism revealed that these plants had Erianthus type cytoplasmic genomes rather than the expected maternal Saccharum type. Target region amplification polymorphism of molecular markers, comparison of morphological characters and pollen size deviation studies confirmed the possible origin of E. arundinaceus type progeny. The diploid pollen from E. arundinaceus plants is considered to be resulted in the diploid androgenesis or paternal apomixis. The diploid androgenesis with paternal transmission of chloroplast and mitochondrial genomes along with the nuclear genome of E. arundinaceus in backcross progeny of Saccharum×Erianthus intergeneric hybrids is the first report in angiosperms.