Peach Palm - Genomics of Cultivated Palms - page 71

7

Peach Palm

7.1 Introduction

Peach palm, or Pejibaye or pupunhua ( Bactris gasipaes Kunth), was the most
important palm of pre-Columbian America. It was a main food crop of Amerindians
and belongs to the subtribe Bactridinae with chromosome number 2 n  28.
Currently, the palm is commercially valuable as heart of palm and for its starchy,
oily fruits. Peach palm has potential as an oil crop and is also rich in carotenes [1] .
Information on the importance, uses, and botany of the palm is available at www.
fao.org/docrep/t0646e/T0646E0l.htm . Molecular markers (allozymes, RAPD,
AFLP, and SSRs) are used to analyze the diversity in wild and domesticated lan-
draces of peach palm. Most of these reports found the lack of genetic differentiation
of wild and cultivated landraces of peach palm. When the hearts (palmitos) of this
palm are harvested, there is very little oxidation and they remain fresh. Polyphenol
oxidase is the enzyme that readily causes oxidation of the tissues, which in turn
causes browning. Peach palm does not express the gene for the polyphenol oxidase
enzyme and hence offers quality [2] . Reviews [3-6] and dissertations [6,7] provide
background information on the genetic diversity of peach palm. Molecular phyl-
ogeny studies on members of the Bactridinae subtribe, Bactris and its species, and
marker studies on landraces, wild populations, and the report on polyphenol oxidase
of peach palm are reviewed and discussed in this chapter.

7.2 Molecular Phylogeny of Bactridinae

The Bactridinae subtribe is part of the Cocoseae tribe of palms, consisting of five
genera and 150 species of spiny Neotropical palms (Acrocomia, Astrocaryum,
Bactris, Aiphanes, and Desmoncus). The genetic relationship of the 41 species of
Bactridinae [8] was analyzed, using five plastid DNA regions (matK, trnQ- rps 16,
rps 16 intron, trnD-trnT, trnL-trnF) along with three nuclear markers (PRK, RPB2,
ITS). The study found Desmoncus and Acrocomia to be sister genera, and together
seen as sister to the rest of the Bactridinae [8] . Two new single-copy nuclear
genes, AGA1 and PHYB, were used for resolving the controversy of relationship
of Bactridinae, especially Astrocaryum and Hexopetion [9] . The Hexopetion clade
was found to be monophyletic in AGA1 and PHYB, but was not strongly support-
ing Astrocarym as a sister. Eiserhardt et al. [8] also found microsatellite repeat in
these sequences, with potential as markers for taxonomy and population genetics [9] .
Analysis of four chloroplast DNA regions, eight microsatellite loci on 38 individuals
of 29 species of Bactris genus along with coconut, Attlaeae crassipatha [9] , found