Soares Sabrina Delgado, Bandeira Ludmila Ferreira, Ribeiro Stela Barros, Telles Mariana Pires de Campos, Silva João Augusto da, Borges Canrobert Tormin, Coelho Alexandre Siqueira Guedes, Novaes Evandro
Universidade Federal de Goiás, Instituto de Ciências Biológicas, Goiânia, GO, Brazil.
Universidade Federal de Goiás, Escola de Agronomia, Goiânia, GO, Brazil.
Genet Mol Biol. 2020 Apr 27;43(2):e20180162. doi: 10.1590/1678-4685-GMB-2018-0162. eCollection 2020.
Given its high-valued wood, the African mahogany (Khaya grandifoliola) has been envisaged as a renewable source of tropical hardwoods in Brazil. However, there are concerns about the hypothesized low diversity among the few K. grandifoliola germplasm sources introduced in the country. Using eight microsatellite markers, we evaluated the genetic diversity and divergence among 53 superior trees selected from three provenances of K. grandifoliola located in the state of Para. These populations are among the oldest plantations (>15 years) in Brazil and, therefore, the country's main seed sources. The average number of alleles per locus was 5.9, expected heterozygosity was moderate (^=0.56) and lower than the high observed heterozygosity (HO=0.74). Therefore, the intrapopulation fixation index was negative (f=-0.31) indicating the possibility that selection of superior trees might have favored heterozygous plants with heterosis. No genetic structure was observed between provenances. The genetic diversity observed within selected trees, with an effective population size (Ne) of 30.4, is comparable to that of natural populations of African and Brazilian mahoganies. Therefore, our results contradict the idea that the genetic diversity of K. grandifoliola introduced in Brazil is low and show that our germplasm can be exploited for breeding purposes.
鉴于非洲桃花心木（大叶卡雅楝）木材价值高，巴西已将其视为热带硬木的可再生资源。然而，人们担心该国引进的少数大叶卡雅楝种质资源之间的多样性可能较低。我们使用八个微卫星标记，评估了从帕拉州三个大叶卡雅楝种源中选出的53株优良树木的遗传多样性和分化情况。这些种群是巴西最古老的种植园（超过15年）之一，因此也是该国主要的种子来源。每个位点的平均等位基因数为5.9，预期杂合度适中（^ = 0.56），低于观察到的高杂合度（HO = 0.74）。因此，种群内固定指数为负（f = -0.31），这表明选择优良树木可能有利于具有杂种优势的杂合植物。在种源之间未观察到遗传结构。所选树木中观察到的遗传多样性，有效种群大小（Ne）为30.4，与非洲和巴西桃花心木的自然种群相当。因此，我们的结果与巴西引进的大叶卡雅楝遗传多样性低的观点相矛盾，并表明我们的种质可用于育种目的。
