Genetic analysis and historical perspective of cashew (Anacardium occidentaleL.) introduction into India

Abstract

Cashew (Anacardium occidentale L.), introduced into India about 400 years ago, is distributed widely in the coastal regions as spontaneous populations as well as in cultivation. Despite the plant's commercial exploitation, little is known about its actual introduction and diversification. We attempted to construct these events by investigating the level of genetic variation and genetic structure of cashew populations collected from different geographical regions of India. A total of 91 individuals from four populations were analysed using AFLP markers and morphometric data. AFLP analysis based on 354 polymorphic loci revealed Indian cashew to have low but relatively substantial genetic diversity for an introduced species (H(E) = 0.262 and I(S) = 0.404). Twenty-seven qualitative and quantitative traits also revealed the existence of considerable morphometric variation (24% around the mean values). Bayesian cluster analysis based on AFLP data did not indicate the existence of definite population differentiation. Morphometric analysis allocated 12% variation among all four populations, whereas AFLP variation observed in cashew individuals was entirely within populations. The results, supporting the possibility of cashew having been introduced into India repeatedly over a period of time but at a single location (west coast), are discussed and their implications for germplasm management are described.

Genetic Diversity of Nigerian Cashew Germplasm

“…In other word, Nigeria shared similar history with India and the first introductions around 400 years ago were planted in the coastal area around Agege, Lagos, Nigeria (Fig. 3), similar to Goa in India (Archak et al, 2009). Spontaneous planting from this coastal area facilitated its spread to other parts of Lower Niger of the country (Woodroof, 1967;Venkataramah, 1976;Togun, 1977;Ohler, 1979 spontaneous spread, cashew trees thrive in the wild for about three centuries (1600-1900s), with no commercial value and exploited mainly for the afforestation and control of gully erosion in most eastern parts of the country with subtropical savannah ecology.…”

“…The world produced about 3.4 million tons of raw cashew nuts in 2009(FAO, 2011 and about one-third of the world cashew nut production comes from Africa with 50% of the continent exports from Nigeria (FAO, 2011) (Table 1). Cashew nut is one of the important agricultural commodities in Africa and has been contributing to Gross Domestic Product (GDP), National Income (NI) and foreign exchange earnings of many of the African cashew producing nations.…”

A morphometric study of the restinga ecotype of Anacardium occidentale (Anacardiaceae): wild coastal cashew populations from Piauí, Northeast Brazil

“…Strictly speaking, the name A. occidentale may be regarded as applicable to one of the domesticated forms of the species, since its type specimen is a plant from Sri Lanka grown in the seventeenth century (Mitchell & Mori ) and presumably derived ultimately from Brazilian genotypes introduced by Portuguese colonists in the 16th century (Archak et al. ). For many authors, however, especially ecologists and taxonomists, the taxon concept (Berendsohn , ) of A. occidentale includes both domesticated and wild forms.…”

“…Although grown commercially and naturalised throughout the tropics today (Archak et al. , Masawe et al. , Nayak et al.…”

“…(), Aliyu & Awopetu (), Pessoni (), Desai (), Archak et al. (), Chipojola et al. (), Dasmohapatra et al.…”