Estimation of genetic diversity in a natural population of cambui tree (Myrciaria tenella O. Berg) using ISSR markers

Cambui (Myrciaria tenella O. Berg) is a native species from Brazil, which belongs to the family Myrtaceae. Molecular characterization is one of the most used tools for the study of the biotechnological potential of species because the diversity level between individuals can be inferred. Analysis of genetic diversity is fundamental to the direction of the strategies necessary to form and maintain a germplasm. This study aimed to evaluate the genetic diversity in a natural population of cambui using inter-simple sequence repeat (ISSR) molecular markers. The natural population, which provided the plant material, is found at the Private Reserve of Natural Heritage of Caju, which belongs to the experimental field of Embrapa Tabuleiros Costeiros, in the municipality of Itaporanga d'Ajuda, SE, Brazil. Young leaves of each individual were collected for DNA extraction and analysis of PCR-ISSR. Thirty primers were tested and the top 10 were selected. The use of these primers resulted in 71 fragments with 98.3% polymorphism. Similarity of individuals ranged between 0.30 and 0.92. The most similar individuals were C13 and C17 and the most distant were C1 and C41. Through UPGMA, six distinct groups were identified. This information may be used for conservation of these genetic resources, germplasm exchange, creation of germplasm bank and in future studies with this species.

New hybrids from peanut (Arachis hypogaea L.) and synthetic amphidiploid crosses show promise in increasing pest and disease tolerance

The primary gene pool of the cultivated peanut (Arachis hypogaea L., allotetraploid AABB) is very narrow for some important characteristics, such as resistance to pests and diseases. However, the Arachis wild diploid species, particularly those from the section Arachis, still have these characteristics. To improve peanut crops, genes from the wild species can be introgressed by backcrossing the hybrids with A. hypogaea. When diploid species whose genomes are similar to those of the cultivated peanut are crossed, sterile hybrids result. Artificially doubling the number of chromosomes of these hybrids results in fertile synthetic polyploids. The objectives of this study were: 1) to obtain progenies by crossing amphidiploids with the cultivated peanut, and 2) to characterize these two groups of materials (amphidiploids and progenies) so that they may be efficiently conserved and used. Using morphological, molecular, and pollen viability descriptors we evaluated one cultivar of A. hypogaea (IAC 503), eight synthetic amphidiploids, and the progenies resulting from four distinct combinations of crossing between IAC 503 and four amphidiploids.