Abstract
Lr34 is a vital gene in developing resistance to leaf rust, stripe rust, and powdery mildew of wheat. Providing simultaneous resistance to various pathogens has made this gene valuable in breeding for wheat resistance to many diseases. The present study investigates the csLV34 marker’s capability in diagnosing this locus in130 wheat commercial cultivars and advanced wheat lines from Iran, and assesses the impact of this gene on disease severity in field conditions. To assess the reactions of cultivars and lines which contained Lr34 under epidemic conditions of leaf rust, these cultivars were cultivated during the 2009 and 2010 cropping season. Of the 130 studied cultivars, 43 contained Lr34. Cultivars that were selected and studied in stress conditions had the most frequent presence of Lr34. It can be concluded that this gene plays a vital role in increasing the tolerance of cultivars under stress conditions. Lr34 seems to cause active transition of materials out of the cell. In addition to being resistant to several important diseases of wheat, Lr34 can increase tolerance to stresses such as salinity. Considering the calculated value for AUDPC (3%-440%/d) in cultivars containing Lr34, it seems that some cultivars contained additional resistance genes. The rate of infection in all cultivars, when presence of Lr34 was detected through the molecular marker, was lower than in other cultivars. Field results confirmed the results of the analysis using the csLV34b molecular marker.
Highlights
Leaf rust caused by Puccinia triticina (Pt) is the most common and widely distributed of the three wheat rusts
This band belongs to the csLV34b allele, which is associated with Lr34
Almost all other Iranian cultivars containing this gene originated from international germplasm, especially from CYMMIT
Summary
Leaf rust caused by Puccinia triticina (Pt) is the most common and widely distributed of the three wheat rusts. Leaf rust is the second most important disease of wheat in Iran but in southern areas leaf rust is the most important disease of wheat [3]. Adult plant gene resistance acts non- on race pathogens in the adult plant stage, and cultivars containing these genes are susceptible at seedling stage and have various levels of comparative resistance to disease at the adult plant stage [6]. This type of resistance is called race non-specific gene resistance since there is no relationship between host genes and pathogen genes. Lr34 resistance has a longer period of infection with fewer and smaller uredinial pustules at two weeks after infection [6,7]
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