Plant Genetics and Rhizosphere Processes Lab, University of Liege, Gembloux Agro Bio-Tech, Terra Research Center, Passage Des Déportés 2, Gembloux, 5030, Belgium.
Faculty of Biological Sciences, Department of Biochemistry-Genetics, Educational and Research Unit of Genetic, University of Peleforo Gon Coulibaly (UPGC), Korhogo, BP 1328, Côte d'Ivoire.
BMC Plant Biol. 2024 Oct 1;24(1):913. doi: 10.1186/s12870-024-05617-0.
The shea tree is a well-known carbon sink in Africa that requires a sustainable conservation of its gene pool. However, the genetic structure of its population is not well studied, especially in Côte d'Ivoire. In this study, 333 superior shea tree genotypes conserved in situ in Côte d'Ivoire were collected and genotyped with the aim of investigating its genetic diversity and population structure to facilitate suitable conservation and support future breeding efforts to adapt to climate change effects.
A total of 7,559 filtered high-quality single nucleotide polymorphisms (SNPs) were identified using the genotyping by sequencing technology. The gene diversity (HE) ranged between 0.1 to 0.5 with an average of 0.26, while the polymorphism information content (PIC) value ranged between 0.1 to 0.5 with an average of 0.24, indicating a moderate genetic diversity among the studied genotypes. The population structure model classified the 333 genotypes into three genetic groups (GP1, GP2, and GP3). GP1 contained shea trees that mainly originated from the Poro, Tchologo, and Hambol districts, while GP2 and GP3 contained shea trees collected from the Bagoué district. Analysis of molecular variance (AMOVA) identified 55% variance within populations and 45% variance within individuals, indicating a very low genetic differentiation (or very high gene exchange) between these three groups (F = 0.004, gene flow Nm = 59.02). Morphologically, GP1 displayed spreading tree growth habit, oval nut shape, higher mean nut weight (10.62 g), wide leaf (limb width = 4.63 cm), and small trunk size (trunk circumference = 133.4 cm). Meanwhile, GP2 and GP3 showed similar morphological characteristics: erect and spreading tree growth habit, ovoid nut shape, lower mean nut weight (GP2: 8.89 g; GP3: 8.36 g), thin leaf (limb width = 4.45 cm), and large trunk size ( GP2: 160.5 cm, GP3: 149.1 cm). A core set of 100 superior shea trees, representing 30% of the original population size and including individuals from all four study districts, was proposed using the "maximum length sub-tree function" in DARwin v. 6.0.21.
These findings provide new knowledge of the genetic diversity and population structure of Ivorian shea tree genetic resources for the design of effective collection and conservation strategies for the efficient use of inbreeding.
乳木果树是非洲著名的碳汇，需要对其基因库进行可持续保护。然而，其种群的遗传结构尚未得到很好的研究，特别是在科特迪瓦。本研究采集并分析了科特迪瓦原位保存的 333 个乳木果树优良基因型，旨在调查其遗传多样性和种群结构，以促进适宜的保护并为适应气候变化的未来育种工作提供支持。
使用测序技术的基因分型共鉴定出 7559 个过滤后的高质量单核苷酸多态性（SNP）。基因多样性（HE）在 0.1 到 0.5 之间，平均值为 0.26，而多态信息含量（PIC）值在 0.1 到 0.5 之间，平均值为 0.24，表明研究基因型具有中等遗传多样性。群体结构模型将 333 个基因型分为三个遗传群（GP1、GP2 和 GP3）。GP1 包含主要源自波洛、塔克洛戈和汉博尔地区的乳木果树，而 GP2 和 GP3 包含来自巴戈埃地区的乳木果树。基于分子方差分析（AMOVA），种群内有 55%的变异，个体内有 45%的变异，这表明这三个群体之间的遗传分化非常低（或基因交流非常高）（F=0.004，基因流 Nm=59.02）。形态上，GP1 表现出展开式树生长习性、椭圆形坚果形状、较高的平均坚果重量（10.62 克）、宽叶（叶宽=4.63 厘米）和较小的树干尺寸（树干周长=133.4 厘米）。同时，GP2 和 GP3 表现出相似的形态特征：直立和展开式树生长习性、卵形坚果形状、较低的平均坚果重量（GP2：8.89 克；GP3：8.36 克）、薄叶（叶宽=4.45 厘米）和较大的树干尺寸（GP2：160.5 厘米，GP3：149.1 厘米）。通过 DARwin v. 6.0.21 中的“最长子树功能”，提出了一个由 100 棵优良乳木果树组成的核心集，代表原始种群大小的 30%，并包括来自四个研究地区的个体。
这些发现为科特迪瓦乳木果树遗传资源的遗传多样性和种群结构提供了新知识，为有效收集和保护策略的设计提供了支持，以实现近交的有效利用。
