Genetic diversity within a population of Microlaena stipoides, as revealed by AFLP markers

Microlaena stipoides (Labill.) R.Br. (microlaena), a C-3 perennial grass, is common within grazed native pastures in the high-rainfall zone (>550mm average annual rainfall) of south-eastern Australia. It has the ability to spread via seed production or vegetatively, using both rhizomes and stolons. This experiment aimed to determine how variable a microlaena population was within a single area, with the aim of determining whether microlaena relied on seed or vegetative spread to sustain populations. Leaf samples of microlaena were collected from 85 locations, sampling two transects, within a pasture at Chiltern, in north-eastern Victoria (36 degrees 12'S, 146 degrees 35'E). The genetic diversity among samples was analysed using amplified fragment length polymorphism (AFLP) markers. We obtained 1612 fragments, using 10 primers combinations. Polymorphism for the markers ranged from 47% to 65%. These results indicated that the populations of microlaena that exist within the pasture at Chiltern are likely to have undergone some degree of outcrossing (F-st=0.0219). It is likely that recruitment is occurring from sexual reproduction as well as via clonal spread within the microlaena population examined. This ability to use vegetative spread as well as both sexual and asexual reproduction may make populations of microlaena more resilient in the longer term.