PARENT SESSION
Oral Session #46: Disturbance Ecology.
Presiding: M. Slocum
Tuesday, August 6. 1:00 PM to 4:45 PM. Grand Ballroom East, Radisson.

Barley yellow dwarf virus reduces growth and fecundity of California native bunchgrasses.

Malmstrom, Carolyn^*,1, ¹ Michigan State University, East Lansing, MI

ABSTRACT- California's valley grasslands are thought to have been dominated by native perennial bunchgrasses prior to European settlement and the introduction of Mediterranean annuals. The bunchgrasses now occupy only a small fraction of these grasslands, and questions have been raised about the likely trajectories of the bunchgrass populations. One set of factors that may be exerting pressure on the bunchgrass populations are the barley yellow dwarf viruses (BYDVs), aphid-vectored luteoviruses best known for reducing yield in cereal grains. I have found BYDV incidence in California bunchgrass populations to be as high as 40%. Could the BYDVs be contributing to the decline of native bunchgrass populations? Using a locally collected BYDV-PAV, I infected seedlings from several California populations of Elymus glaucus (blue wildrye), E. multisetus (big squirreltail), Hordeum brachyantherum (meadow barley), Koeleria macrantha (junegrass), and Nassella pulchra (purple needlegrass) and grew them in the field in Davis, California, for one complete growing season. Response differed somewhat between species and populations, but BYDV infection generally reduced total aboveground biomass, inflorescence count, and seed production, in some cases by 50%. These findings demonstrate that BYDV-PAV can reduce fecundity and may lower recruitment and survivorship in some California bunchgrasses.

KEY WORDS: grassland, disturbance, barley yellow dwarf virus, pathogen