Molecular characterization of local varieties of cassava cultivated by Uarini flour producers in the Tefé region, Amazonas Brazil
Manihot esculenta; microsatellites; ISSR; Uarini flour.
Cassava (Manihot esculenta Crantz) is produced throughout Brazil due to its easy adaptation to different climates and soils, and plays an important role in generating employment and income. This research is part of the Interdisciplinarity for the Strengthening of the Uarini Flour Production Chain - Ethnobotany and Genetic Diversity of Manihot esculenta Crantz project, and aims to perform the molecular characterization of local varieties of cassava cultivated by Uarini flour producers in the Tefé region, Amazonas Brazil. Sampling was carried out in the Uarini Geographical Indication area, comprising the municipalities of Uarini, Alvarães, Tefé, and Maraã, located in the state of Amazonas. The study was conducted at UNEMAT Alta Floresta, in the GenBioMol Laboratory. DNA extraction was performed using the CTAB method from 48 local varieties of cassava cultivated in the Uarini GI. Subsequently, PCR was performed using ISSR and SSR molecular markers. The products of the ISSR-PCR were converted into a binary matrix of the presence and absence of bands, and the SSR-PCR products were sent to FIOCRUZ for genotyping. The 12 SSR primers amplified a total of 78 alleles, with an average of seven per primer. Most primers showed observed heterozygosity higher than expected. PIC varied from 0.07 (SSRY43) to 0.83 (SSRY35), with an average of 0.55. Fifteen rare alleles and 30 exclusive alleles were found. AMOVA revealed greater genetic variation within populations than between populations. The UPGMA method and Bayesian analysis formed three groups each. The seven ISSR primers amplified 82 fragments, with 51 polymorphic ones. The average percentage of polymorphism was 62.20%. PIC ranged from 0.21 (UBC 834) to 0.60 (TRI GTG), with an average of 0.32. The UPGMA clustering method formed three groups and Bayesian analysis formed two. There is genetic diversity among the local varieties of cassava studied, which is greater within populations than between populations, a result that may have been favored by the exchange of cassava cuttings among producers. The clustering methods used did not separate local varieties by collection location. Genetic divergence among local varieties represents an important factor for the preservation of the species, as well as a potential to be explored in conservation and cultivation reproduction programs of the species, or even in breeding programs, with a focus on the Alvarães population, which showed the highest number of rare alleles and exclusive alleles.