Fescue - locoid introgression as a source of novel germplasm for the pasture industry.

Abstract

Lolium and Festuca are two closely related temperate grasses grown worldwide for forage and which are known to hybridise readily. The aim of this research was to characterise F2 Festulolium hybrids so that useful germplasm could be identified.

The DNA content of all F2 hybrids was estimated using both PI and DAPI stains for flow cytometry. FISH and GISH was performed on selected F2 hybrids to determine chromosome number and origin. An ISSR specific to F. arundinacea (Pašakinskiene et al. 2000) was assessed for its ability to identify the percent of parental origins of each F2 hybrid using qPCR. Growth rates of plants in a randomised complete block, followed by leaf morphology were examined for correlations to estimated ploidy. The fertility of the F2 hybrids was observed using FDA staining of pollen.

The DNA content of the F2 hybrids ranged from 5.34 to 26.66 pg of DNA, indicating an estimated ploidy range from diploid to decaploid. Four plants with different chromosome numbers showed recombination between Lolium and F. arundinacea DNA. Recombination was more frequent in the plants containing more chromosomes. The ISSR marker was unable to be obtained and use of a second ISSR marker was unable to be optimised sufficiently to obtain percent parentage using qPCR, although presence or absence of either parental genome could be detected using PCR. Morphological investigations showed that the Lolium plants and some diploid F2 hybrids had no or few stomata on the underside of their leaves. The number of stomata correlated positively with ploidy. High fertility, judged by pollen viability, of some F2 hybrids correlated with 2n, 4n, or 6n estimated ploidy; low fertility with aneuploidy.

A diverse range of variation was observed between the F2 hybrids, ranging from plants that more resembled either parent or were a morphological mixture between the two. The hybrids may be a valuable source of novel variation for future pasture development.