ABSTRACT
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. (AU)
Subject(s)
Arachis , Sexual Behavior, Animal , Breeding , Amazonian Ecosystem , GenotypeABSTRACT
Eighteen enzyme systems were examined in Ilex paraguariensis St. Hil. using starch gel electrophoresis. Seven out of 12 active isozyme systems revealed one or more polymorphic loci (PGI, GOT, MR, G-6PDH, MDH, NDH, and 6-PGDH). However, the segregation and linkage analyses were performed only for PGI, GOT, G-6PDH and 6-PGDH systems. Gene segregation at these loci was regular, except for a few trees that showed segregation distortion. Weak linkage disequilibrium between loci was detected, but it was not enough to influence the multilocus estimate.
Dezoito sistemas enzimáticos foram analisados em Ilex paraguariensis, utilizando eletroforese em gel de amido. Sete dos 12 sistemas que apresentaram atividade enzimática revelaram um ou mais locos polimórficos (PGI, GOT, MR, G-6PDH, MDH, NDH e 6-PGDH). Entretanto, as análises de segregação e desequilíbrio de ligação foram realizadas somente nos sistemas PGI, GOT, G-6PDH e 6-PGDH. A segregação destes locos foi regular, exceto para algumas árvores, que apresentaram distorções de segregação. Foram detectados indícios de desequilíbrio de ligação entre alguns locos, mas que não devem influenciar as estimativas multilocos.