Genetic diversity in populations of African mahogany (Khaya grandioliola C. DC.) introduced in Brazil

Abstract

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 Pará. 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 (H E =0.56) and lower than the high observed heterozygosity (H O =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.

SNP-based analysis reveals unexpected features of genetic diversity, parental contributions and pollen contamination in a white spruce breeding program

“…It is not clear if this value reflects a positive selection for heterozygotes in the residual population, which might be possible if the SNPs are linked to loci under selection 24 . Previous genetic diversity studies of Khaya grandioliola also revealed such an excess of heterozygotes, with a relatively large negative inbreeding coefficient ( F i = −0.31) estimated from 53 superior trees from three provenances in Brazil 37 . Furthermore, if the inbreeding coefficient is negative after roguing, it would suggest than more homozygotes than heterozygotes have been removed, which indeed could be a result of slight inbreeding depression.…”

Biometric assessment of early stem growth at a commercial stand of African mahogany (Khaya grandifoliola)

“…), which has great production potential, high commercial value, and low incidence of pests. African mahogany, which was previously introduced in Brazil, has a wide genetic diversity that is comparable to that of natural species (Soares et al 2020). The growing demand for tropical wood from reputable and responsible origins has led to new investments in plantations throughout the country, ultimately directing the forest market toward new potential species (Reis et al 2019).…”

Indolbutyric Acid (IBA) in the african mahogany (Khaya grandifoliola C. DC.) cuttings and mini-cuttings development

“…is a high sized heliophile tree, reaching 40 meters in height, featured by a brownish-pink wood, currently planted in many regions of Brazil (Reis et al, 2019). The species K. grandifoliola has a broad brazilian introduced genetic diversity, promptly available to be explored silviculturally (Soares et al 2020). For many years been mistakenly treated as Khaya ivorensis.…”