Daramcoum et al., J. Appl. Biosci. 2017 Diversité agro-morphologique précoce d'hybrides d'autofécondation F3 de cocotier impliquant l'écotype Nain Vert Sri Lanka (NVS) tolérant à la maladie du Jaunissement Mortel. 11052Journal of Applied Biosciences 112: 11045-11051 ISSN 1997-5902 Diversité agro-morphologique précoce d'hybrides d'autofécondation F3 de cocotier (Cocos nucifera L.) impliquant l'écotype Nain Vert Sri Lanka (NVS) tolérant à la maladie du Jaunissement Mortel 11053ABSTRACT Early agro-morphological diversity assessment in self-pollination coconut (Cocos nucifera L.) hybrids F3 involving Sri Lanka Green Dwarf (SGD) ecotype tolerant to Lethal Yellowing (LY) disease of Ghana Objectives: To obtain morphological diversity precociously in self-pollination dwarf coconut cross generations created in Côte d'Ivoire, mature hybrid seeds and seedlings were studied. Indeed, in coconut palm where the period between planting and fruiting times varies from 3 years, the full morphological characterization at the field takes a long duration. Methodology and results: Twenty-one morphological traits measured on the mature hybrid seeds and seedlings from F3 CRD x SGD, F3 PILD05 x SGD and F2 MYD x MYD (control) hybrids were studied. The results revealed two morphological clusters as different genetic pools which one gathers self-pollination hybrids F3 implying the ecotype Sri-Lanka Green Dwarf (SGD) tolerant to the Lethal Yellowing (LY) disease and the other control cross F2 MYD x MYD sensitive to LY. Three types of morphological traits (types I, II and III) implied in the differentiation of the tolerant and sensitive hybrids relatively to LY disease were also identified. Conclusion and implementation of the results: For Côte d'Ivoire coconut breeding program, these two identified genetic pools and the quantitative traits that characterize them could be exploited in the research of the QTLs associated with LY disease tolerance in coconut palm.

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.