Postgraduate Program in Botany, Instituto Nacional de Pesquisas da Amazônia, Manaus, Amazonas, Brazil.
Department of Genetic, Universidade Federal do Amazonas, Manaus, Amazonas, Brazil.
PeerJ. 2023 Jan 23;11:e14659. doi: 10.7717/peerj.14659. eCollection 2023.
Biribá ( Jacq.) is a fruit tree domesticated in Amazonia and has polyploid populations. The species presents ample phenotypic variation in fruit characteristics, including weight (100-4,000 g) and differences in carpel protrusions. Two cytotypes are recorded in the literature (2 = 28, 42) and genome size records are divergent (2C = 4.77, 5.42 and 6.00 pg). To decipher the role of polyploidy in the domestication of , we examined the relationships among phenotypic variation, chromosome number and genome size, and which came first, polyploidization or domestication.
We performed chromosome counts of from central and western Brazilian Amazonia, and estimated genome size by flow cytometry. We performed phylogenetic reconstruction with publicly available data using a Bayesian framework, time divergence analysis and reconstructed the ancestral chromosome number for the genus and for .
We observed that variation in fruit phenotypes is not associated with variation in chromosome number and genome size. The most recent common ancestor of is inferred to be polyploid and diverged before domestication.
We conclude that, when domesticated, was already polyploid and we suggest that human selection is the main evolutionary force behind fruit size and fruit morphological variation in .
Biribá（Jacq.）是一种在亚马逊地区驯化的果树，具有多倍体种群。该物种在果实特征上表现出丰富的表型变异，包括重量（100-4000 克）和心皮突出程度的差异。文献中记录了两种细胞型（2 = 28、42），基因组大小记录也存在差异（2C = 4.77、5.42 和 6.00 pg）。为了解析多倍体在驯化中的作用，我们研究了表型变异、染色体数和基因组大小之间的关系，以及多倍化和驯化哪个先发生。
我们对来自巴西亚马逊中心和西部地区的进行了染色体计数，并通过流式细胞术估算了基因组大小。我们使用贝叶斯框架、时间分歧分析和重建了属和 的祖先染色体数，从公开数据中进行了系统发育重建。
我们观察到果实表型的变异与染色体数和基因组大小的变异无关。的最近共同祖先被推断为多倍体，在驯化之前就已经分化了。
我们得出结论，在驯化时，已经是多倍体，我们认为人类选择是果实大小和果实形态变异的主要进化力量。
