Genetic characterization of promising high-yielding cashew (Anacardium occidentale L.) cultivars from Côte d'Ivoire

Abstract

Description of the subject. Cashew was introduced to Côte d'Ivoire in 1951 to control erosion and reforest cutover lands. From 1972 to 1980, natural forest plantations were converted to fruit orchards and were supplemented by the ‘Jumbo’ cashew variety imported from Brazil. Germplasm expeditions conducted in 2010 and 2014–2015 identified 209 high-yielding cultivars in the major cashew growing areas of Côte d’Ivoire. Although the morphological characteristics of these cultivars have been assessed, little is known about the genetic diversity and genetic structure of the germplasm collection. Objectives. The objective of the study was to evaluate the genetic diversity of high-yielding cashew cultivars for better use in breeding programs. Method. We performed DNA isolation using Qiagen DNeasy Plant Mini Kits and PCR analysis with 18 SSR markers. Results. We identified the first two introduced populations of cashew in Côte d’Ivoire. The average allelic richness is 3.56 (± 1.45) alleles per locus, the fixation index (FIS) indicates an overall heterozygosity deficit of 0.332 (± 0.076), and the average population differentiation (FST) is 0.014 (± 0.004). Much of the total genetic variability occurs at the intra-population level (98.6%), compared to only 1.4% variability attributable to differences between populations. Average value of gene flow is 22.528. Conclusions. Gene flow within cashew populations maintains high intra-population genetic diversity. This flow rate reflects a long-term exploitable genetic variability for use in selection and conservation.

Keywords

• genetic variation
• ecotypes
• côte d’ivoire