Stem rust fungus. Different from most fungi, the rust variations have five spore stages and alternate between two hosts. Wheat is the primary host, and barberry is the alternate host. There are multiple pathotypes (including QCC and MCC) affecting barley, within "forma specialis tritici". The stem rust fungus attacks the parts of the plant that are above ground. Spores that land on green wheat plants form a pustule that invades the outer layers of the stalk. Infected plants produce fewer tillers and set fewer seed, and in cases of severe infection the plant may die. Infection can reduce what is an apparently
Wheat leaf rust role in resistance breeding for cultivated crops. The earliest single resistance gene was identified as effective against yellow rust. Numerous single genes for leaf rust resistance have since been identified, the 47th genes prevent crop losses due to "Puccinia recondite" Rob. Ex Desm. f.sp. "tritici" infections, which can range from 5% to 15% depending on the stage of crop development. Leaf rust resistance gene is an effective adult-plant resistance gene that increases resistance of plants against "P. recondita" f.sp." tritici" (UVPrt2 or UVPrt13) infections, especially when combined with genes Lr13 and gene Lr34 (Kloppers & Pretorius, 1997). Lr37 originates from