Intl. J. of Mol. Evol. and Biodivers. 2015, Vol. 5, No. 1, 1-5
1
Research Report Open Access
Molecular Assessment of
Cocos nucifera
L. Var. Sri Lanka Yellow Dwarf for
Genetic Purity and
Aceria
Mite Tolerance
S. A. C. N. Perera , L. C. J. Kamaral, W. B. S. Fernando
Genetics and Plant Breeding Division, Coconut Research Institute, Lunuwila, 61150, Sri Lanka
Corresponding author email
International Journal of Molecular Evolution and Biodiversity, 2015, Vol.5, No.1 doi: 10.5376/ijmeb.2015.05.0001
Received: 10 Dec., 2014
Accepted: 12 Jan., 2015
Published: 30 Jan., 2015
© 2015 Perera et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Perera et al., 2015, Molecular Assessment of
Cocos nucifera
L. Var. Sri Lanka Yellow Dwarf for Genetic Purity and
Aceria
Mite Tolerance,
International
Journal of Molecular Evolution and Biodiversity, Vol.5, No.1, 1-5
(doi
Abstract
World-over, coconut is classified broadly into tall and dwarf phenotypes. The dwarf coconut variety is further divided into
forms based on the colour of the epicarp. The Sri Lanka Yellow Dwarf (SLYD) coconut variety was observed to have individuals of
differing phenotypes and this variety also showed varying degrees of tolerance to
Aceria guerreronis
(Keifer), which is a pest
infesting coconut causing economic losses. This study was aimed at the evaluation of the coconut form SLYD for varietal
confirmation and the tolerance to
Aceria
mite at the microsatellite marker loci. Twenty five sample palms drawn randomly from four
morphological groups based on stature and tolerance to
Aceria
mite were genotyped at seven SSR marker loci along with Sri Lanka
Tall (SLT) and Sri Lanka Green Dwarf (SLGD) as reference varieties. Three SSR loci were highly informative for the SLYD
population and the results revealed the presence of a population structure within the SLYD coconut population. A clear clustering was
observed for tall like and the dwarf like groups with more variation within the tall like group. Clear allelic identifications were
established at several SSR loci for the clustering based on stature and the markers were identified for distinguishing different groups.
The study provided evidence for the need for reclassification and purification of SLYD coconut population. Certain associations were
present for the character
Aceria
mite tolerance, indicating the potential for marker assisted selection.
Keywords
Coconut; SSR markers; Varietal classification; Aceria mite; Marker assisted selection
Introduction
Coconut palm is an important oil crop in the tropics. It
is also important as a tree crop with diverse uses, such
that every part of this palm can be economically used.
In its varietal classification, two main types of
coconuts have been identified world-over, namely the
tall (
Typica
) group and the dwarf (
Nana
) group. In
addition to these two types several intermediate type
coconut populations have also been identified in
certain countries. Tall coconut varieties display tall
stature, larger crowns and a prominent swelling at the
base of the stem forming a root bole. In contrast, the
dwarf coconut varieties are shorter in stature, produce
a smaller crown and are lacking a root bole. The dwarf
coconut varieties are further distinguished into four
groups by the colour of the epicarp of the fruit as
green (
pumila
), yellow (
eburnea
), red (
regia
) and
brown (
braune
). The intermediate coconut varieties
possess certain features from the tall group and the
rest from the dwarf group (Liyanage, 1958).
There are two sub groups within the tall coconuts; the
South East Asian/Pacific group and the South
Asian/African group. The dwarf coconuts are
presumed to have evolved from the tall coconuts of
the South East Asian/Pacific group (Perera et al.,
2000). The dwarf varieties are mainly homozygous
purelines while the tall coconuts are naturally
cross-pollinating, heterogenous populations having
varying degrees of heterozygosity. Consequently, the
allelic diversity of tall coconuts is naturally higher
while there is a reduction of allelic diversity in the
dwarf coconuts.
In Sri Lanka all the four forms of dwarf coconuts, i.e.
green, yellow, red and brown are found. These dwarf
coconut varieties are not popular as commercial
coconut cultivars but are extensively used as a parent
in inter-varietal hybrid coconut production. The
