Genetic diversity and population structure ofToona ciliatarevealed by simple sequence repeat markers

Abstract

Toona ciliata (Meliaceae) is a rare, fast-growing commercial tree species that produces red timber with beautiful grains. It used to be widely distributed in the past, but few natural forests exist in the field now. Here, we tested 12 nuclear microsatellite markers derived from 551 individuals of 29 populations in China, and investigated the genetic diversity and population structure in T. ciliata. Our results revealed 146 alleles obtained from all of the populations studied here, with an average polymorphic information content of 0.723. The populations could be divided into two major genetic lineages using STRUTURE analysis: 14 and 15 populations from different provinces clustered in Western and Eastern genetic lineages, respectively. The genetic differentiation among the two genetic lineages was 28%. The genetic diversity of the Western lineage was higher than that of the Eastern lineage. Moreover, a Mantel test of the relationship between genetic and geographic distances revealed significantly positive correlations both among all 29 populations and within the Eastern genetic lineage, whereas there was no significant correlation in the Western genetic lineage. Therefore, in the conservation strategy of T. ciliatare sources, the two genetic lineages should be treated independently. To the best of our knowledge, these data are the first detailed characterization of the genetic structure and diversity of T. ciliata populations using nuclear microsatellite markers. The obtained results lay the foundation for preservation of the T. ciliata germplasm resources and support further artificial breeding efforts.

Comparative transcriptomes and genetic diversity assessment of two Sichuan peppers (Zanthoxylum bungeanum and Zanthoxylum armatum)

“…Nevertheless, the findings of the present study indicate that at the level of both species and variety, there appears to be relatively low genetic diversity among the three species Z. bungeanum, Z. armatum, and Z. piperitum. Moreover, we were unable to detect any substantial regional variation, which can probably be attributed to the parthenocarpic mode of reproduction, which is a notable characteristic of these species and has been widely investigated in other species [26]. Apomixis is considered a primary factor contributing to this category of result, and because reproduction in most Zanthoxylum species occurs via apomixis, this is probably a key factor associated gene stability and low genetic diversity.…”

Mating system and population structure in the natural distribution of Toona ciliata (Meliaceae) in South China

“…Pollen flow of T. ciliata could be mainly entomophilous, and seed dispersal is mainly mediated by wind together with birds 9 , with an anticipation of a certain level of population genetic differentiation. Previous studies demonstrated that population differentiation of T. ciliata was substantially large, with F st = 0.792 among range-wide populations assayed with nuclear SRAP 13 and 0.324 with nuclear SSR loci among 29 populations 4 . The present study also indicated significant genetic differentiation (F st = 0.345) among the six populations, and detected significant IBD effects among the six populations.…”

“…The present study also indicated significant genetic differentiation (F st = 0.345) among the six populations, and detected significant IBD effects among the six populations. Zhan et al 4 showed that IBD effects were absent among populations in the western part but present in the eastern part. IBD effects among populations could likely affect mating system since mating systems differed in different regions under significant IBD effects 29 .…”

“…Here we investigated mating system of six natural populations distributed in South China. Previous studies with SRAP (sequence-related amplified polymorphism) and nuclear microsatellites (simple sequence repeats, SSRs) indicated that substantial genetic variation (about 79.26% with SRAP versus 32.4% with SSR) occurred among populations 4,13 . The range-wide distribution of T. ciliata was grouped into two clusters, the western and eastern parts.…”

“…We used nuclear SSRs because of the attributes of highly informative microsatellite markers for paternity/parentage and mating system analyses 14,15 . SSR primers that were previously screened in T. ciliata were used for individual genotyping 4 . Besides, population genetic structure among the six populations was analyzed and then combined with the estimates of mating systems to inform strategies for managing this endangered forest species in China.…”