Biology Reference
In-Depth Information
6
Arecanut
6.1 Diversity of
Areca
There are very few reports available on molecular markers on arecanut. Moderate
genetic diversity is observed in cultivated arecanut varieties, using 19 random ampli-
fied polymorphic DNA (RAPD) primers. Genetic distance
[1]
varied from 0.22
(between Sree Mangala and Maidan Local) to 0.47 (between Mohitnagar
inter se
and
Mohitnagar). RAPD primers of OPM, OPAF, and OPC series were screened in are-
canut
[2]
for testing clonal fidelity, where OPAF02 gave polymorphic bands when
amplified at 42 °C for 1 min. Nine microsatellite loci (AC01, AC06, AC07, AC08,
AC14, AC23, AC28, AC29, and AC30) were developed in areca
[3]
. All these loci
differed in Hardy-Weinberg equilibrium except AC30. Linkage disequilibrium was
seen only between AC06 and AC08 loci. Molecular markers linked to important
traits of arecanut such as dwarf habit, high tannins, low arecoline, and arecaidine
content are not yet available.
6.2 Molecular Phylogeny of
Areca
Areca
and seven other genera,
Gronophyllum
,
Gulubia
,
Hydriastele
,
Loxococcus
,
Nenga
,
Pinanga
, and
Siphokentia
[4]
, form the Arecinae subtribe (
Figure 6.1
).
Areca, Nenga
, and
Pinanga
form the areca clade, a major group in the subtribe
(
Figure 6.2
). In this subtribe, intron sequences from phosphoribulokinase (PRK)
and the second largest subunit of RNA polymerase II (RPB2) were employed to
study the phylogenetic analysis. PRK intron showed an amplicon with a size of
700 base pair (bp) and a 50 bp variation among the members of the subtribe.
Areca
had a GC-rich homopolymer in PRK intron as a unique feature. RPB2 intron dis-
played an amplicon of 850 bp consistently across the Arecinae. These two DNA
variations were useful in Arecinae to understand the relationships of the subtribe
and its genera, and to examine the evolution of dichogamy, with different levels
of protandry and protogyny
[5]
. Intron sizes of PRK phosphoribulokinase (PRK;
a Calvin cycle enzyme) and malate synthase (MS; a glyoxylate cycle enzyme)
showed amplicons of 900-1300 and 500 bp, respectively
[6]
, in Areceae, the largest
tribe of the Arecaceae family. DNA variations in these two low-copy nuclear loci
were useful in constructing the phylogeny of the Areceae tribe with 17 subtribes
and 54 species.
