Using marker-aided selection to improve tree growth response to abiotic stress

Abstract

The ability to locate quantitative trait loci (QTL) on a restriction fragment length polymorphism (RFLP) genetic linkage map will provide tree breeders the means to overcome some currently intractable problems inherent to breeding long-lived tree species. These RFLP–QTL maps will allow early, indirect, marker-aided selection (MAS) in breeding programs. This paper explores the opportunities and limitations of MAS, an approach to developing an RFLP–QTL marker map, and use of the map in breeding loblolly pine (Pinustaeda L.) for improved growth response to abiotic stress; specifically, drought stress. Growth responses under moderate drought stress are important to long-term forest productivity, because on most sites loblolly pine is subjected to growth-limiting moisture stress during part of almost every growing season. MAS provides new precision and reliability in identifying and breeding trees that are able to continue growth under moderate stress, and perhaps provides a unique opportunity for improving tree productivity on moderately stressful sites. Traits potentially related to growth under stress are identified, and their suitability for placement and use on an RFLP–QTL linkage map is discussed.