Gene Diversity in Grevillea Populations Introduced in Brazil and Its Implication on Management of Genetic Resources

Abstract

-We describe isoenzymes variability in six populations of Grevillea robusta from a provenances and progenies test established in a randomized block design with five plants per replication in Southern Brazil. The population genetic structure was examined by using biochemical markers in 5-year old trees, specifically at MDH-3, PGM-2, DIA-2, PO-1, PO-2, SOD-1, and SKDH-1 loci. The northern provenances (Rathdowney and Woodenbong) showed a strong divergence in relation to the average of provenances when alleles per locus (Ap), allele richness (Rs), Nei's gene diversity (H), and inbreeding coefficient (f) were considered. Inbreeding in varying degrees was detected. The commercial control showed the highest inbreeding coefficient, (f = 0.4448), whereas the provenance average was f = 0.2306, possibly due to insufficient sampling of populations in their origin (Australia). Despite its restricted natural range, a positive correlation between genetic divergence and geographic distance among original populations was detected. Genetic distance and cluster analyses based on the Bayesian model revealed three distinct provenance groups: 1) Rathdowney-QLD and Woodenbong-QLD; 2) Paddy's Flat-NSW; and 3) Mann River-NSW, Boyd River-NSW and the commercial control (material used in Brazil). The grouping of the control to both Mann River-NSW and Boyd River-NSW provenances suggests that the northern provenances have the highest potential for genetic improvement of wood productivity in Brazil, due to their high genetic diversity and low inbreeding coefficient. RESUMO -A variabilidade isoenzimática para seis populações de Grevillea robusta, oriundas de um teste de procedências/progenies, implantado no delineamento em blocos casualizados com 5 plantas por parcela, no Sul do Brasil, é descrita. A estrutura genética da população foi analisada utilizando-se marcadores bioquímicos, aos 5 anos de idade, especificamente para os locos MDH-3, PGM-2, DIA-2, PO-1, PO-2, SOD-1, e SKDH-1. As procedências do norte de ocorrência natural (Rathdowney e Woodenbong) apresentaram divergência genética superior, em relação à média das progênies, considerando o número de alelos por locus, (Ap), a riqueza alélica (Rs), a diversidade genética de Nei (H), e o coeficiente de endogamia (f). A endogamia foi detectada em diversos graus. A testemunha comercial apresentou o maior coeficiente de endogamia, (f = 0,4448), comparativamente à média das procedências (f = 0,2306), possivelmente devido à insuficiente amostragem populacional na região de origem (Austrália). Apesar de sua ocorrência natural restrita, observou-se correlação positiva entre divergência genética e distância geográfica entre as populações originais. A distância genética e análise de cluster, baseada no modelo bayesiano, mostrou três grupos de procedências distintos: 1) Rathdowney-QLD e Woodenbong-QLD; 2) Paddy's Flat-NSW; e 3) Mann River-NSW, Boyd River-NSW e a testemunha comercial (material utilizado no Brasil). O agrupamento da testemunha com as procedências Mann River-NSW e Boyd River-NSW...

Genome skimming-based simple sequence repeat (SSR) marker discovery and characterization in Grevillea robusta

“…The amplification rate was significantly higher as compared to Liquidambar formosana (72%) (Chen et al 2020 ). The genotyping of 48 accessions of G. robusta with 13 SSRs generated 35 alleles with an average of 2.69 alleles per locus, which is similar to that recorded in Brazilian sampled individuals of G. robusta using isoenzymes (2.93 alleles per locus) (Sousa et al 2018 ). However, this is lower to one of the members of a Proteaceae family ( Conospermum undulatum ) in which an average of 11.45 alleles per locus were recorded for 20 microsatellite loci (Delnevo et al 2019 ).…”

“…Before our study, genetic variation was examined in 23 populations of G. robusta across the natural range in Australia using 20 isozyme loci (Harwood et al 1997 ), where the mean expected heterozygosity was recorded as low (H e = 0.105) with a low level of genetic differentiation. Whereas, in another isoenzymes-based study conducted in Brazilian populations, high levels of genetic diversity (H o = 0.3962 and H e = 0.5140) was recorded (Sousa et al 2018 ). Earlier, one of the inter simple sequence repeats (ISSR)-based studies carried out with a relatively smaller numbers of genotypes from one (GRUK) of the four presently sampled locations also revealed comparable results (H o = 0.290 and H e = 0.305) (Parmar et al 2019 ).…”

“…Again, similar sets of admixing were shown by PCoA and UPGMA cluster analysis, which tend to justify the low value of F ST . Concomitantly, the genetic differentiation among Australian populations (Harwood et al 1997 ) and Brazilian germplasm (Sousa et al 2018 ) of G. robusta was also recorded as low. Thus, it could be inferred that the gene flow across the spatially separated populations was sufficiently maintained and not greatly affected by the ecological and geographical attributes.…”

Cost benefit analysis for Grevillea robusta in Ethiopia: linking establishment of a breeding seedling orchard to the economic returns of quality plantings

“…Somewhat similar isozyme patterns were obtained by Sousa et al (2018) who compared diversity in five natural populations of grevillea from Australia with a commercial control from Brazil. This control was developed from Australian trees of unknown origin.…”

Molecular Analyses used in Genetic Diversity Studies of Bioactive Plants of Verbenaceae and Lamiaceae: A Review

“…Lately, the isoenzymatic molecular markers and RFLP have been poorly used. Conversely, depending on the species, they may still be useful [42]. Despite their great collaboration at the beginning of genetic diversity studies of several plant species, they were replaced by more modern techniques, which have greater reproducibility and specificity in accessing species genomes.…”