A Genetic Linkage Map of Diploid Paspalum notatum

Abstract

Paspalum notatum Flugge is a subtropical grass native to South America. The most common form in the USA is P. notatum var. saurae Parodi (Pensacola bahiagrass), which is a valuable forage. Pensacola bahiagrass is a sexual diploid, while most other races of P. notatum are apomictic tetraploids. The objective of this work was the construction of a genetic linkage map of diploid P. notatum (2n = 2x = 20) that can be used as a framework for basic genetic studies as well as breeding purposes. The mapping population derived from a cross between the genotypes Q408410 and Tift9 that originated from Cayastá, Santa Fe, Argentina, and Tifton, GA, USA, respectively. Heterologous restriction fragment length polymorphism (RFLP) clones of maize (Zea mays L.), rice (Oryza sativa L.), and oat (Avena sativa L.) were used to cover the Paspalum genome uniformly in a comparative approach, while random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers were added to condense the linkage groups. A combined map was constructed with the markers segregating from both parental genotypes by the program JoinMap 1.4. A total of 149 marker loci were used for map construction. One hundred twelve loci were allocated to 10 linkage groups, covering a total map distance of 991 centimorgan (cM). The average distance between markers was about 9 cM. Paspalum Linkage Groups 1, 3, 4, 5, 6, 8, and 10 showed syntenic regions with maps of maize and rice. Moreover, several RFLP loci reported to be associated with apomixis in hybrids of maize‐Tripsacum and Brachiaria were located on the map. This study provides a genetic linkage map of a subtropical forage grass with both sexual and apomictic forms, which can be used for investigating simple and complex traits.