Gopaulchan David, Motilal Lambert A, Bekele Frances L, Clause Séverine, Ariko James O, Ejang Harriet P, Umaharan Pathmanathan
1Cocoa Research Centre, The University of the West Indies, Sir Frank Stockdale Bldg., St. Augustine, 330912 Republic of Trinidad and Tobago.
Sunshine Agro Products Ltd, 24, Avenue de la Toison d'Or, 1050 Brussels, Belgium.
Physiol Mol Biol Plants. 2019 Mar;25(2):361-375. doi: 10.1007/s12298-018-0632-2. Epub 2019 Jan 1.
Cocoa is among the top foreign exchange earners in Uganda's agriculture sector and has benefitted the livelihood of farmers involved in production. Although cacao cultivation was adopted in the early 1900s, little is known about the on-farm diversity of the crop. A total of 125 cacao landraces were surveyed from eight districts in the Central and Western Regions to evaluate the morphological and genetic diversity of cacao in Uganda. Passport data included site, tree, fruit and seed information. Trees were genotyped using 96 single nucleotide polymorphism markers on a Fluidigm platform. Low heterozygosity was detected in the germplasm in both the Central [observed heterozygosity ( ) = 0.295, expected heterozygosity ( ) = 0.334] and Western Regions ( = 0.317, = 0.322). Genetic variation in both regions was generally comparable but the regions could be differentiated from each other. Inbreeding was noted in the Central Region while a greater sharing of genetic material was observed in the Western Region. The morphological and genetic data indicated that the Ugandan collection was an interspersed group with low to moderate variation with some separation of the Central from Western regions. Ancestry analysis indicated that the majority of the accessions were hybrids of Marañon lineage but also had Amelonado and Iquitos genetic backgrounds. These findings are consistent with the history of the movement of cacao into Uganda. A core collection of 18 individuals to represent the genetic diversity as well as 12 additional trees with possible advantageous traits is proposed.
可可在乌干达农业部门的外汇收入中名列前茅，惠及了从事可可生产的农民的生计。尽管可可种植于20世纪初被引入，但人们对该作物的农场内多样性了解甚少。从乌干达中部和西部地区的八个区共调查了125个可可地方品种，以评估乌干达可可的形态和遗传多样性。产地数据包括种植地点、树木、果实和种子信息。利用Fluidigm平台上的96个单核苷酸多态性标记对树木进行基因分型。在中部地区[观察杂合度（ ）=0.295，期望杂合度（ ）=0.334]和西部地区（ =0.317， =0.322）的种质中均检测到低杂合度。两个地区的遗传变异总体相当，但两个地区可以相互区分。中部地区存在近亲繁殖现象，而西部地区观察到更多的遗传物质共享。形态和遗传数据表明，乌干达的样本是一个低到中等变异的散布群体，中部和西部地区有一定分离。祖先分析表明，大多数种质是马拉尼翁谱系的杂种，但也有阿梅洛纳多和伊基托斯的遗传背景。这些发现与可可传入乌干达的历史一致。建议建立一个由18个个体组成的核心种质库来代表遗传多样性，另外再选12棵具有可能有利性状的树木。
