Identification of RAPDs associated with resistance to lethal yellowing of the coconut ( Cocos nucifera L.) palm

Abstract

Lethal yellowing (LY) is a disease of phytoplasma etiology that has devastated coconut ( Cocos nucifera L.) cultivation for over a century. The only effective means for controlling LY is replanting with resistant germplasm. Breeding coconuts for any desirable traits is hindered by the long generation time, low multiplication rate, and ineffective clonal propagation of this crop. Additionally, the lack of genotypes adequate for identifying markers linked with LY resistance demands alternative approaches. We identified three coconut populations which could be used for this purpose, and comprised the susceptible West African Tall (WAT), the resistant Malayan Yellow Dwarf (MYD), and a resistant population of Atlantic Tall (AT) plants. This latter material was closely related to WAT, and both of them were distantly related to MYD. The objective of this work was to use those populations for identifying RAPDs associated with LY resistance. RAPDs were considered as associated with that trait if their frequencies were high in MYD and AT, and low in WAT. A total of 82 RAPDs could differentiate the DNA pools from MYD and WAT, and 12 of them appeared at frequencies ≥0.85 in MYD, and ≤0.15 in WAT. Five of such markers were in AT at frequencies of 0.80 (−B4 570) or 1 (−A11 990, −B11 1140, −AL3 1160 and −AL7 350). The results are discussed in terms of the prospects for marker-assisted selection of LY-resistant plants.