VIEW ARTICLE

Resistance

Effect of Germ Tube Length on the Fate of Sporelings of Puccinia hordei in Susceptible and Resistant Barley. R. E. Niks, Plant Breeding Department (IvP), Agricultural University, P.O. Box 386, 6700 AJ Wageningen, The Netherlands; Phytopathology 80:57. Accepted for publication 26 June 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-57.

Within leaves of barley, there is great variation in fate among individual sporelings of Puccinia hordei. Some sporelings abort at one or another stage of the infection process; others establish colonies that vary in rate of growth and development. Histological examination of barley leaves 6 days after inoculation with P. hordei in three experimental series revealed a negative association between germ tube length of sporelings and the chance of successful establishment of a colony. This effect was found in a susceptible, a hypersensitive, and two partially resistant barley lines. Within these lines there was a significant negative correlation between germ tube length and size of the established colony. It is suggested that the formation of a long germ tube, necessary to reach a stoma, decreases the amount of energy available to the sporelings to infect the host.