Genetic diversity in wild populations of the restinga ecotype of the cashew (Anacardium occidentale) in coastal Piauí, Brazil

Abstract

The cashew, Anacardium occidentale, is a globally important tropical fruit tree, but little is known about its natural infraspecific systematics. Wild Brazilian populations occur in the cerrado biome and coastal restinga vegetation. We investigated whether wild coastal and domesticated populations could be distinguished genetically using inter-simple repeat molecular markers (ISSRs). In total, 94 polymorphic loci from five primers were used to characterise genetic diversity, structure and differentiation in four wild restinga populations and four domesticated ones from eight localities in Piauí state (30 individuals per population). Genetic diversity was greater overall in wild (%P: 57.2%, I: 0.24, H e : 0.15) than domesticated populations (%P: 49.5%, I: 0.19, H e : 0.12). Significant structure was observed among the eight populations (between-population variance 22%, Φ PT = 0.217, P ≥ 0.001), but only weak distinctions between wild and domesticated groups. Cluster and principal coordinate analyses showed marked genetic disparity in populations. No correlation of genetic and geographical interpopulation distance was found (Mantel test, r = 0.02032, P = 0.4436). Bayesian analysis found an eight-group optimal model (ΔK = 50.2, K = 8), which mostly corresponded to sampled populations. Wild populations show strong genetic heterogeneity within a small geographical area despite probable gene flow between them. Within-population genetic diversity of wild plants varied considerably and was lower where extractive activities by local people are most intense (Labino population). The study underlines the importance of wild populations as in situ genetic reserves and the urgent need for further studies to support their conservation.

Genetic diversity and identification of interspecific hybrids of Anacardium species using microsatellites

“…In cashew, a number of genetic diversity studies have been conducted in the germplasm from different regions of the world using the molecular markers, viz. RAPD, AFLP and ISSRs (Mneney et al 2001;Archak et al 2003a, b;Archak et al 2009;Thimmappaiah et al 2009;Aliyu 2012;Borges et al 2018;Santos et al 2019).…”

Recent Large-Scale Genotyping and Phenotyping of Plant Genetic Resources of Vegetatively Propagated Crops

“…Cashew: Despite its importance, intra- and interspecific genetic structure has been sparsely studied in cashew. Genetic diversity was analyzed using ISSR markers in 240 wild-type accessions [ 115 ], while SSR loci were used to identify endangered populations and develop conservation strategies in the related species A. humile St.-Hil. [ 116 ].…”

Potential antioxidant and antibacterial bioactivity of leaf and stem bark extracts in wild cashew (Anacardium occidentale L.) populations from coastal Piauí, northeastern Brazil

“…Anacardium L. is one of 14 genera of this family occurring in Brazil and includes the economically important cashew fruit tree, Anacardium occidentale L., used for nutrition, medicines and industrial products (Mitchell & Mori 1987; Barbosa‐Filho et al 2014; Silva‐Luz & Pirani 2015). Studies of various kinds of chemical and biological activity have been carried out on domesticated cashews, cultivars or naturalized forms of this species in Brazil and other parts of the tropical world, where for economic reasons A. occidentale has spread by human agency since the 16 th century, particularly India and Africa (Mitchell & Mori 1987, Andrade et al 2019, Santos et al 2019); e.g. anti‐inflammatory activity (Olajide et al 2004; Olajide et al 2012), antifungal activity (Fenner et al 2006), cicatrization (Schirato et al 2006) and wide‐spectrum antimicrobial effects (Dahake et al 2009; Ajileye et al 2015).…”

“…1F) than those of the domesticated cashew (known as caju ). In their morphometric study of the restinga ecotype, Andrade et al (2019) presented a detailed discussion of the confused application of the vernacular name cajuí in a range of other studies of the species, and this is also referred to by Santos et al (2019) in their population study of the molecular genetics of the restinga ecotype.…”

“…Baptista (2018) and Baptista et al (2018) reported on antioxidant and antimicrobial activity in samples from the cerrado of Tocantins state in central Brazil. All these authors identified their material from natural populations ( cajuí ) as A. microcarpum Ducke, but as Andrade et al (2019) and Santos et al (2019) have recently discussed, this name should not be used because it refers to plants from Amazonia, which are considered by taxonomists to be included in A. occidentale (Mitchell & Mori 1987, Silva‐Luz & Pirani 2015). All the above‐cited studies are here regarded as investigations of wild cerrado ecotype populations of A. occidentale .…”