Rattans and Palmyra - Genomics of Cultivated Palms - page 58

5

Rattans and Palmyra

5.1 Introduction

Rattans are spiny climbing palms used in making cane furniture and mats, an industry that
is growing at US$4 billion trade per year. Rattans belong to the subfamily Calamoideae
of the family Arecaceae. The Calamoideae subfamily consists of 22 genera and nearly
650 species [1] . Genomics were useful in phylogeny reconstruction of Calamodeae, and
the molecular taxonomy of Calamus and related genera is an important research focus.
Rattans are harvested from forests that require conservation efforts. Assessment of genetic
diversity in rattans in diversity hotspots aids in identifying gene erosion, and priority loca-
tions and species for conservation. Sex identification of the Calamus seedling is a priority
because the plant takes 5 years to enter the reproductive phase. Molecular markers associ-
ated with sex in rattan are needed to identify the sex at an early stage.
Palmyra ( Borasssus flabellifer L.) is a long-lived perennial dioecious palm com-
mon in dry tropics, especially in Asia and Africa. Inflorescence sap is tapped from
the palms and is used in making sugar and alcoholic beverages. The fruit of the palm
is also edible. Molecular markers are useful in analyzing the diversity, trait-marker
association in sex, dwarf habit, and high sap yield.

5.2 Molecular Markers for Rattans

5.2.1 Molecular Phylogeny
Members of the Calamoideae subfamily were analyzed with a sample of DNA from
40 or 41 species. Sequence variations in one internal transcribed spacer (ITS) region
in a nuclear gene 18S-26S nrDNA [2] cistron and an intron of the ribosomal pro-
tein rps 16 of chloroplast, each of ~900 bp size, were analyzed in these species [2] .
ITS regions of the calamoid palms (671 bp size) displayed polymorphism. Using
three internal primer sets in the ITS regions, two internal regions, ITS1 and ITS2,
of 163-243 bp size, were sequenced in the palms. Mean size of the rps 16 intron of
palms was found to be 870 bp. Calameae was demonstrated as a paraphyletic group
including Lepidocaryeae, using these two loci. Raphia , the African genus, is found
to be a sister clade to the Lepidocaryeae. African and Asian rattans formed two sepa-
rate monophyletic groups except Eugeissona [3] . Success of the nuclear 5S nontran-
scribed spacer region in classification of the palm genus Phoenix [4] inspired the use
of this region in DNA for classification and relationship analysis of Calamus and
five related genera [5] . The amplified PCR product of PIII and PIV primers of the 5S
spacer in the rattans ranged from 85 to 413 bp. Results of the 5S nrDNA data found
the genus Calamus to be a paraphyletic group with four major lineages [5] .