A Newly Found Leaf Rust on Aegilops speltoides in Israel

Aegilops speltoides (2n = 14, genome "S") shows resistance to wheat foliage diseases, including both leaf rust species which attack wheats and Aegilops spp. Naturally infected plants of Ae. speltoides with leaf rust, were found in 1997 at Ahihud, Western Galilee, Israel. The disease reappeared in 1998 at the same site and was found also on Ae. speltoides plants at Qazir, Samarian Mountains. Artificial inoculations, with uredial cultures, gave positive results on diploid Aegilops species carrying "S" genome and on Aegilops spp. carrying "U" and "M" genomes. Negative results were recorded on bread and durum wheats (including the most susceptible varieties Thatcher and Chinese-Spring) and a set of Chinese Spring ditelosomic lines. The alternate host proved to be Thalictrum speciosissimum. The S₁ and S₂ generations had a similar host-range as the original isolates. Crossing experiments with wheat leaf rust gave positive results. Teliospore and basidiospore dimensions, as well as the nuclear DNA content (measured in pycnospores) showed great similarity to P. triticina. - the "wheat leaf rust" and not to the P. recondita the "Aegilops leaf rust". The implications of this research are important, due to the use of A. speltoides as a source of resistance in wheat breeding.