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<p>Cashew trees are recognized for their economic and ecological importance in the tropics, but their species delimitations and phylogenetic relationships remain unclear. Here, we analyzed the genetic diversity of their germplasms from the Cerrado and restinga biomes in Northeastern Brazil. Twenty-four accessions of <i>Anacardium occidentale</i> and two of <i>A</i>. <i>humile</i> were evaluated using morphological and genetic markers. The morphological variability extended beyond species boundaries, challenging their differentiation. Furthermore, molecular analyses of selected nuclear (<i>ITS</i>) and plastid (<i>matK</i>, <i>trnL-F</i>, <i>ycf1</i> and <i>rps16</i>) DNA regions revealed no clear genetic separation between <i>A</i>. <i>occidentale</i> and <i>A</i>. <i>humile</i>, resulting in an unresolved clade. We also performed cytogenetic analyses and genome size measurements on twelve accessions of <i>A</i>. <i>occidentale</i> along with two of<i> A</i>. <i>humile</i> to investigate possible undetected genomic differentiation. The results indicated a strong chromosomal stability, with <i>2n</i> = 40, CMA<sup>+</sup>/DAPI<sup>−</sup> bands in the terminal regions of the short arm of three chromosome pairs, one pair of 5S rDNA, and three pairs of 35S rDNA sites co-localized with CMA<sup>+</sup>/DAPI<sup>−</sup> bands. Genome sizes were similar among the accessions, with a mean genome size of 0.44&#xa0;pg/1C (~435 Mbp), suggesting no significant intra- or interspecific variation and no evidence of polyploidy. The lack of differentiation among the analyzed accessions reinforces the need for expanding the present analysis to test if it may be attributed to incomplete lineage sorting, hybridization with introgression, or the possibility that <i>A. occidentale</i> and <i>A. humile</i> represent a single species, with domesticated accessions exhibiting larger fruits and pseudofruits.</p>

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Does size matter? Morphological and genetic similarities between cashew (Anacardium occidentale) and cajuí (A. humile)

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Acalene Gonçalveis-Oliveira,
  • Thiago Nascimento,
  • Priscila Alves Barroso,
  • Cíntia Luíza da Silva-Luz,
  • Silvokleio da Costa Silva,
  • Andrea Pedrosa-Harand

摘要

Cashew trees are recognized for their economic and ecological importance in the tropics, but their species delimitations and phylogenetic relationships remain unclear. Here, we analyzed the genetic diversity of their germplasms from the Cerrado and restinga biomes in Northeastern Brazil. Twenty-four accessions of Anacardium occidentale and two of A. humile were evaluated using morphological and genetic markers. The morphological variability extended beyond species boundaries, challenging their differentiation. Furthermore, molecular analyses of selected nuclear (ITS) and plastid (matK, trnL-F, ycf1 and rps16) DNA regions revealed no clear genetic separation between A. occidentale and A. humile, resulting in an unresolved clade. We also performed cytogenetic analyses and genome size measurements on twelve accessions of A. occidentale along with two of A. humile to investigate possible undetected genomic differentiation. The results indicated a strong chromosomal stability, with 2n = 40, CMA+/DAPI− bands in the terminal regions of the short arm of three chromosome pairs, one pair of 5S rDNA, and three pairs of 35S rDNA sites co-localized with CMA+/DAPI− bands. Genome sizes were similar among the accessions, with a mean genome size of 0.44 pg/1C (~435 Mbp), suggesting no significant intra- or interspecific variation and no evidence of polyploidy. The lack of differentiation among the analyzed accessions reinforces the need for expanding the present analysis to test if it may be attributed to incomplete lineage sorting, hybridization with introgression, or the possibility that A. occidentale and A. humile represent a single species, with domesticated accessions exhibiting larger fruits and pseudofruits.