Application of molecular markers for biodiversity and taxonomy studies in legume tree species from the miombo woodlands, Niassa Natioanl Reserve, Mozambique

Miombo is one of the most important types of vegetation of southern Africa covering about 70% of the region. This ecosystem has an immeasurable socio-economic and environmental value. However, its stability is increasingly being threatened by climate viariability, herbivory, fire and human activities. This study demonstrates the importance of using molecular markers, Inter Simple Sequence Repeats (ISSRs) and barcodes respectively for biodiversity and taxonomy studies of miombo species in one of the most valuable conservation areas of the globe, the Mozambican Niassa National Reserve (RNN). Comparative ISSR analysis of two legume tree species: Brachystegia boehmii Taub. and Burkea africana Hook. F. was performed along a fire gradient (East-West). The results indicated a strong relationship between tolerance to fire and genetic diversity that was considerably higher in B. africana (tolerant to fire). Neverthless, while in the case of B. africana the western population showed higher variability than that from the east (0.2977 versus 0.2184 genetic heterozigocity), the opposite was observed for the fire-sensitive B. bohemii (0.1482 versus 0.2059). The contrasting percentage of ISSR polymorphic bands in the east region when compared to the west sector (60.0% versus 90.0% for B. africana and, oppositely, 68.1% versus 48.9% for B. bohemii) supports this observation. This opposite trends may be related to fire tolerance and adaptation. In any case, the high levels of genetic diversity in both species does not appear to be compromised. This observation is in agreement with the fact that the RNN is one of the least disturbed areas of deciduous miombo. Regarding genetic barcodes, the study focused on the isolation and sequencing of two taxonomic markers: matK and rbcL genes, encoding two chloroplast proteins, maturase K and ribulose - 1,5 bisphosphate, respectively, of three legumes: B. boehmii, B. africana and Pterocarpus angolensis DC. Both genes showed an adequate potential for discrimination of species, confirming their usefulness for taxonomic, phylogenetic and evolutionary studies.