Genetic evidence of multiple invasions and a small number of founders of Asian Palmyra palm (Borassus flabellifer) in Thailand

Abstract

Background Borassus flabellifer or Asian Palmyra palm is an important crop for local economies in the South and Southeast Asia for its fruit and palm sugar production. Archeological and historical evidence indicated the presence of this species in Southeast Asia dating back at least 1500 years. B. flabellifer is believed to be originated in Africa, spread to South Asia and introduced into Southeast Asia through commercial routes and dissemination of cultures, however, the nature of its invasion and settlement in Thailand is unclear.ResultsHere, we analyzed genetic data of 230 B. flabellifer accessions across Thailand using 17 EST-SSR and 12 gSSR polymorphic markers. Clustering analysis revealed that the population consisted of two genetic clusters (STRUCTURE K = 2). Cluster I is found mainly in southern Thailand, while Cluster II is found mainly in the northeastern. Those found in the central are of an extensive mix between the two. These two clusters are in moderate differentiation (F ST = 0.066 and N M = 3.532) and have low genetic diversity (HO = 0.371 and 0.416; AR = 2.99 and 3.19, for the cluster I and II respectively). The minimum numbers of founders for each genetic group varies from 3 to 4 individuals, based on simulation using different allele frequency assumptions. These numbers coincide with that B. flabellifer is dioecious, and a number of seeds had to be simultaneously introduced for obtaining both male and female founders.ConclusionsFrom these data and geographical and historical evidence, we hypothesize that there were at least two different invasive events of B. flabellifer in Thailand. B. flabellifer was likely brought through the Straits of Malacca to be propagated in the southern Thailand as one of the invasive events before spreading to the central Thailand. The second event likely occurred in Khmer Empire, currently Cambodia, before spreading to the northeastern Thailand.Electronic supplementary materialThe online version of this article (10.1186/s12863-017-0554-y) contains supplementary material, which is available to authorized users.

Transferability, development of Single Sequence Repeat (SSR) markers and application to the analysis of genetic diversity and population structure of the African fan palm (Borassus aethiopumMart.) in Benin

“…We identified 57 potential SSR markers, of which 11 displayed polymorphism and were used to assess the genetic structure of B. aethiopum populations in Benin. We find a low genetic diversity, with an average He value (0.354) that is substantially below those reported for Borassus flabellifer [46] and for other non-timber forest products such as Khaya senegalensis (He = 0.53; [80] and Phyllanthus sp [81]. The positive F value that we observed in the majority (6 out of 9) of populations in the present study indicates an overall deficiency of heterozygotes across population.…”

“…Similarly, it is plausible that differences in genome size and complexity among palm species and genera account for our difficulty to identify palm SSR markers that successfully amplify in B. aethiopum . As a matter of fact, the size of the B. aethiopum genome, as determined by flow cytometry (1C = 7.73 Gb; Jaume Pellicer, unpublished data), is 3.2 to 11.5 times larger than those of the microsatellite source species used in the present study: the date palm genome is estimated to be 671 Mb [40] whereas the oil palm genome is 1.8-1.9 Gb [41,74] and the coconut genome is 2.42 Gb [46]. Most likely, these differences in genome sizes among related diploid plant species rely on differences in Transposable Element contents and associated structural variations such as copy number variants and homologous recombinations [75], which might eventually affect the cross-species amplification ability of SSR primers.…”

Transferability, development of simple sequence repeat (SSR) markers and application to the analysis of genetic diversity and population structure of the African fan palm (Borassus aethiopum Mart.) in Benin

“…We identi ed 57 microsatellite loci, from which we selected 11 markers displaying polymorphism that were used to assess the genetic structure of B. aethiopum sampled from different sites in Benin. We nd low genetic diversity, with an average He value (0.354) that is substantially below those reported for B. abellifer (0.417) [45] and for other non-timber forest products such as Khaya senegalensis (0.53) [65] and Phyllanthus sp. (0.607 and 0.582 for P. emblica and P. indo scheri respectively [66].…”

“…[37], Phoenix dactylifera L. [38][39][40] and Cocos nucifera L. [41,42]. In each of these three palm species, large numbers of SSR markers have been identi ed and for a fraction of them, cross-species and cross-genera transferability tests among species belonging to the Palmaceae family have been performed [43][44][45][46][47][48][49]. In several instances [44][45][46][47]49] these tests included samples from B. abellifer, the Asian relative of B. aethiopum.…”

RNA editing in the chloroplast of Asian Palmyra palm (Borassus flabellifer)

“…Borassus flabellifer or Asian Palmyra palm, a member of Arecaceae family, is widespread in Southeast Asia (Pipatchartlearnwong et al, 2017). It is grouped in Coryphoideae subfamily with Phoenix dactylifera (date palm).…”