Effect of leaf rust resistance gene Lr34 on components of slow rusting at seven growth stages in wheat

Leaf rust resistance gene Lr34 is known to confer slow rusting resistance in wheat (Triticum aestivum). We conducted greenhouse experiments to evaluate the effect this gene had on three components (latent period, uredinium size and receptivity) of slow rusting resistance at seven plant growth stages of the Lr34 near-isogenic lines Jupateco 73R and Jupateco 73S at three temperatures (13, 18 and 23degreesC). The presence of Lr34 increased the latent period and reduced uredinium size and receptivity. Although effects of Lr34 could be seen at each growth stage, differences in latent period and receptivity between the isolines increased dramatically from the 4-leaf stage onwards and stabilized by the 5-leaf stage. The relative effect of the Lr34 gene on latent period decreases and the receptivity increases with increasing temperature. Uredinium size was least affected by temperature and growth stage.