Molecular diagnosis of phytoplasma transmission from zygotic embryos to in vitro regenerated plants of coconut palm (Cocos nucifera L.)

Abstract

The aim of this study was to investigate the transmission of the lethal yellowing disease (LYD) of coconut tree caused by a phytoplasma from the zygotic embryo to the regenerated plantlet in vitro. From a total of 30 trees, 150 mature coconut nuts where harvested. These nuts were used to extract 150 zygotic embryos. From this package, 96 zygotic embryos were used to regenerate 96 young coconut seedlings in vitro and the 54 others were used to extract total DNA. From the stem of the 30 palms at the stage 1 of the LYD, phloem sample were also collected. From the regenerated in vitro-plantlets at 6 months age, leaf sample were collected. From the molecular diagnosis by PCR, 80% of the phloem samples carried the 16S rRNA gene of the phytoplasma responsible for LYD. All the zygotic embryos and in vitro-plantlets regenerated were healthy. So, coconut zygotic embryos can be used for the safe exchange of genetic material regarding lethal yellowing disease. The regenerated in vitro plantlet are free of disease.