Genetic and genomic analysis in the Hevea genus aiming to contribute to the genetic improvement of Hevea brasiliensis

The rubber tree (Hevea brasiliensis), species originating in the Amazon region, has great economic importance because it is the largest source of natural rubber. Such polymer has properties that cannot be obtained from synthetic materials, such as abrasion resistance, electrical and gas insulation and resilience, being used for the most different purposes, such as the manufacture of tires and hospital medical equipment. However, due to the occurrence of a disease in its region of origin, caused by the contamination of young leaves by the fungus Pseudocercospora ulei, it became necessary to implement this culture in regions favored climatically for the development of such an organism. For this reason, the adaptation of the species in contrasting regions when compared to its center of origin, also known as escape areas, became necessary, being one of the main objectives of breeding programs, especially those developed by the Agronomic Institute of Campinas. Because it has a long improvement cycle of about 30 years, the use of new techniques can represent a reduction in this time. In this context, the molecular markers SNPs (single nucleotide polymorphisms) appear, they can assist breeding programs using the technique of genotyping-by-sequencing (GBS), which allows the discovery and simultaneous genotyping of large amounts of SNPs. Genetic map of the mapping population from the crossing of PB217 with PR255, contrasting for the characteristics of cold tolerance and high productivity was constructed, using markers developed in other works together with those based on the GBS technique. A map composed of 18 linkage groups and a length of 4693 cM was obtained, containing a total of 1062 markers, of which 576 are based on GBS. Using 368 individuals from a genotyped panel using the same technique, using principal coordinate analysis for 2221 markers, the separation of individuals into two distinct groups was found, those corresponding to mostly breeding individuals and wild individuals, which they were then used for the evaluation of linkage disequilibrium (LD), with different patterns of LD being evidenced, the breeding individuals presented an average LD of 0.49 against 0.02 of the wild individuals. Another linkage map was created from a mapping population from the genitors GT1 and RRIM701, obtaining a linkage map with 3779.3 cM and 1079 markers, then detecting QTLs, 38 of which 24 were identified for stem diameter, seven for height and seven for number of nodes (AU)