ABSTRACT.Arachis pintoi and A. repens are legumes with a high forage value that are used to feed ruminants in consortium systems. Not only do they increase the persistence and quality of pastures, they are also used for ornamental and green cover. and eight of A. repens were analyzed using 17 microsatellites, and the observed heterozygosity (H O ), expected heterozygosity (H E ), number of alleles per locus, discriminatory power, and polymorphism information content were all estimated. Ten loci (58.8%) were polymorphic, and 125 alleles were found in total. The H E ranged from 0.30 to 0.94, and H O values ranged from 0.03 to 0.88. By using Bayesian analysis, the accessions were genetically differentiated into three gene pools. Neither the unweighted pair group method with arithmetic mean nor a neighbor-joining analysis clustered samples into species, origin, or collection area. These results reveal a very weak genetic structure that does not form defined clusters, and that there is a high degree of similarity between the two species.

RESUMOO setor agropecuário brasileiro tem apresentado crescente participação na economia, especialmente no mercado exportador mundial, onde a pecuária de corte tem destaque. O desafio é continuar a aumentar a produção e, simultaneamente, reduzir o desmatamento. Investimentos em tecnologia buscam tornar a pecuária mais sustentável, como o uso de gramíneas consorciadas com leguminosas forrageiras. O amendoim forrageiro (Arachis pintoi) destaca-se dentre as leguminosas forrageiras por seu alto teor de proteína, boa cobertura do solo e compatibilidade com gramíneas, além da fixação biológica de nitrogênio. O programa de melhoramento do amendoim forrageiro tem como objetivo desenvolver novas cultivares adaptadas aos diversos climas do território brasileiro. Os marcadores moleculares são ferramentas importantes nesse processo, fornecendo informações sobre a divergência genética em banco de germoplasma, taxa de reprodução cruzada, e também no processo de certificação de hibridação.

The search for alternatives to increase productivity and sustainability of livestock production in the Amazon region without increasing deforestation is challenging. Mixed pastures of grasses with forage peanut (Arachis pintoi) have shown positive economic impacts. However, gaps in the knowledge of the reproductive biology of A. pintoi have limited the development of new cultivars adapted to the environmental variations in the Brazilian Amazon. Pasture consortiums of Brachiaria humidicola with forage peanuts (cv. Mandobi) resulted in a 42% increase in weight gain productivity. New cultivars better adapted to the Amazon climate should bring even greater gains. We evaluated the mating system in twenty A. pintoi accessions, and approximately 40 offspring per accession genotyped with eight microsatellites (or markers). The parameters of genetic diversity and inbreeding, the outcrossing rate and coancestry were calculated. The observed heterozygosity was significantly higher and the fixation index was significantly lower in adults compared with the offspring. The crossing rate was variable among genotypes (2 to 80%), and the mean outcrossing rate was 36%. These results indicate that pollinator presence in pastures can influence gene flow in A. pintoi more than expected. Arachis pintoi presented a mixed mating system with a predominance of selfing, and families presented inbreeding and different levels of relatedness. New strategies of genotype conservation are needed to avoid pollinator-mediated crossing between accessions.

The rubber tree (Hevea brasiliensis) is native to the Amazon region, and it is widely exploited due to natural rubber produced from latex. There are many clonal varieties, without certification tests. In order to determine a genetic certification, 15 clones were genotyped to identify their genetic pattern. Ten microsatellites were used to determine a subset of alleles exclusive for each genetic profile. The genetic estimates obtained were: number of alleles per locus (N), expected (HE) and observed (HO) heterozygosity, Polymorphic Information Content (PIC) and Discriminatory Power (DP). The number of alleles (N) ranged from five to 14, with an average of 9.2. The HE mean (0.80) was higher than HO (0.60), indicating a selection for homozygotes. The locus informativeness was verified with PIC (0.77) and DP (0.90) means showing high polymorphism. The dendrogram represented the formation of three groups related to geographical origin. Clone MDF 180 presented the highest genetic divergence. Two genic pools represented the genetic composition of genotypes. Based on allelic profiles, a set of two microsatellites (A2365 and A2368) was able to distinguish all examined clones. The genetic certification using microsatellite fingerprinting proved to be an alternative to morphological traits.