QTL Mapping of Growth-Related Traits in a Full-Sib Family of Rubber Tree (Hevea brasiliensis) Evaluated in a Sub-Tropical Climate

Abstract

The rubber tree (Hevea spp.), cultivated in equatorial and tropical countries, is the primary plant used in natural rubber production. Due to genetic and physiological constraints, inbred lines of this species are not available. Therefore, alternative approaches are required for the characterization of this species, such as the genetic mapping of full-sib crosses derived from outbred parents. In the present study, an integrated genetic map was obtained for a full-sib cross family with simple sequence repeats (SSRs) and expressed sequence tag (EST-SSR) markers, which can display different segregation patterns. To study the genetic architecture of the traits related to growth in two different conditions (winter and summer), quantitative trait loci (QTL) mapping was also performed using the integrated map. Traits evaluated were height and girth growth, and the statistical model was based in an extension of composite interval mapping. The obtained molecular genetic map has 284 markers distributed among 23 linkage groups with a total length of 2688.8 cM. A total of 18 QTLs for growth traits during the summer and winter seasons were detected. A comparison between the different seasons was also conducted. For height, QTLs detected during the summer season were different from the ones detected during winter season. This type of difference was also observed for girth. Integrated maps are important for genetics studies in outbred species because they represent more accurately the polymorphisms observed in the genitors. QTL mapping revealed several interesting findings, such as a dominance effect and unique segregation patterns that each QTL could exhibit, which were independent of the flanking markers. The QTLs identified in this study, especially those related to phenotypic variation associated with winter could help studies of marker-assisted selection that are particularly important when the objective of a breeding program is to obtain phenotypes that are adapted to sub-optimal regions.

Comparison of three QTL detection models on biochemical, sensory, and yield characters in Coffea canephora

“…For this reason, we used co-dominant markers (SSRs) to facilitate both the map construction and QTL detection (Van Ooijen 2006;Van Ooijen 2009;Jourjon et al 2005). This type of approach was proved to be successful in other plant species (Clement et al 2003;Souza et al 2013). In our study, the two bi-parental maps were similar for both genetic map sizes and number of loci mapped.…”

Mapeamento de QTL para qualidade de frutos de citros utilizando marcadores DArT-seq

“…Garcia et al (2006) SOUZA et al, 2013;GAZAFFI et al, 2014). A co-localização de QTLs tem sido utilizada principalmente em espécies florestais, como em Pinus taeda (BROWN et al, 2003), Pinus pinaster (POT et al, 2006) e Picea glauca (PELGAS et al, 2011;PETROLI, 2013), como uma maneira de sugerir possíveis genes candidatos ou para validar genes candidatos de forma indireta.…”

Arquitetura genética de componentes periódicos de crescimento de Hevea brasiliensis

“…Souza et al (2013) realizaram um importante trabalho, desenvolvendo um mapa de ligação e mapeamento de QTLs para caracteres de crescimento, considerando duas estações climáticas de verão e inverno.…”

“…(GONCALVES et al, 1998;COSTA et al, 2000;GONCALVES et al, 2005;FURLANI et al, 2005) e, desde 1927, numerosas pesquisas tem sido feitas para investigar a resistência de H. brasiliensis ao MDF por institutos de pesquisa e empresas como a Ford, Goodyear, Firestone e Pirelli (RIVANO et al, 2013;SOUZA et al, 2013).…”

“…Com o advento dos marcadores moleculares, novas possibilidades para caracterização dos genótipos estão sendo propostas, bem como análises de diversidade genética, estabelecimento de relação entre características de interesse agronômico com regiões no genoma (QTLs) e a identificação de genes de interesse (BESSE et al, 1994;LOW et al, 1996;VARGHESE et al, 1997;LESPINASSE et al, 2000;GUEN et al, 2003;SAHA, 2004;NAZEER, 2005;SOUZA et al, 2009;GUEN et al, 2011;YU et al, 2011;SOUZA et al, 2013).…”