Is There Genetic Variability in Dwarf Coconut Accessions Preserved in Brazil?

Abstract

Dwarf coconut tree is the main variety for commercial use in Brazil, which ranks fourth in world coconut production. However, the genotypes used still have limitations and genetic variability is required. The aim of this study was to estimate the genetic variability in dwarf coconut accessions preserved at the Germplasm Bank of Brazil at different harvesting times and using agronomic descriptors of plant and fruits. The accessions Brazilian Green Dwarf-Jiqui, Cameroon Red Dwarf, Malayan Red Dwarf, Brazilian Red Dwarf-Gramame, Brazilian Yellow Dwarf-Gramame, and Malayan Yellow Dwarf were assessed by means of 30 descriptors Variance analysis was performed and the genetic diversity was quantified by using the Mahalanobis’ generalized distance and expressed by means of UPGMA clusters, Tocher optimization, and canonical variables. The maximum likelihood analysis was used to estimate the components of variance with the data of each plant in a sample of 11 descriptors of great importance for the genetic improvement of the coconut tree. A phenotypic divergence was found among the accessions using the UPGMA clusters, Tocher optimization and graphic dispersion obtained with canonical variables. The use of the maximum likelihood analysis confirms the existence of genetic variability in the accessions for the descriptors fruit polar and equatorial diameter, nut polar diameter, total fruit weight, and epicarp thickness, which presented a heritability varying from 0.17 to 0.39. There is a possibility of genetic gains with the selection of these traits for use of accessions in breeding programs.

Genomic and population characterization of a diversity panel of dwarf and giant coconut accessions from the International Coconut Genebank for Latin America and Caribbean

“…Characterizing the diversity and genetic structure of the accessions conserved in germplasm banks is extremely important for monitoring diversity, allowing breeders enough time and information to develop and apply strategies for maintaining and amplifying the diversity present in the bank and to exploit this diversity in breeding programs. Some studies have already been conducted to characterize the diversity and genetic structure of coconut accessions conserved in the International Coconut Genebank for Latin America and the Caribbean (ICG-LAC) with morphological markers (Sobral et al 2018(Sobral et al , 2019 Studies of genetic diversity and population structure performed with SNPs markers are becoming increasingly frequent thanks to the robustness of the results generated by the markers (Fischer et al 2017) when large sets of marks are analyzed, the cheapening and democratization of access to sequencing platforms and advances in bioinformatics (Li et al 2017). SNPs markers provide relevant information with high reliability regarding the genetic variability of the germplasm bank of a species and how this variability is structured, and are a direct platform for the application of modern breeding techniques.…”