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Stemphylium blight (caused by Stemphylium botryosum Wallr.) is one of the major diseases of lentil (Lens culinaris Medik.) in South Asia and North America. The objective of the study was to identify linkage map position of the genes conferring resistance to stemphylium blight and the markers linked to the genes for its utilization in marker-assisted breeding. A population of 206 [F.sub.7]-derived recombinant inbred lines (RILs) was developed from a cross between ILL-6002 (resistant) and ILL-5888 (susceptible). The RILs were planted in disease-screening plots at Ishurdi, Bangladesh in the 2006-2007 and 2008-2009 winter cropping seasons. Significant variation was detected among RILs for disease scores and frequency distributions suggested complex inheritance. An intraspecific linkage map was constructed that comprised 139 markers; 21 simple sequence repeats (SSR), 27 randomly amplified polymorphic DNA (RAPD), 89 sequence related amplified polymorphism (SRAP) markers and 2 morphological markers distributed over 14 linkage groups. One significant quantitative trait loci (QTL) was detected based on disease scores from the 2006-2007 experiment while three significant QTLs were detected from the 2008-2009 experiment. The QTL [QLG4.sub.80-81] was common in both years and accounted for 25.2 and 46.0% of the variation of disease scores in 2006-2007 and 2008-2009 experiments, respectively. Two SRAP markers, ME5XR10 and ME4XR16c, and one RAPD marker, UBC34, located on linkage group 4, were significantly associated with the [QLG4.sub.80-81] in both crop years. After validation, the more tightly linked ME4XR16c marker may be used for marker assisted selection for stemphylium blight resistance. doi: 10.2135/cropsci2009.12.0709

Stripe rust is a devastating fungal disease that afflicts wheat in many regions of the world. New races of Puccinia striiformis, the pathogen responsible for this disease, have overcome most of the known race-specific resistance genes. We report the map-based cloning of the gene Yr36 (WKS1), which confers resistance to a broad spectrum of stripe rust races at relatively high temperatures (25[degrees] to 35[degrees]C). This gene includes a kinase and a putative START lipid-binding domain. Five independent mutations and transgenic complementation confirmed that both domains are necessary to confer resistance. Yr36 is present in wild wheat but is absent in modern pasta and bread wheat varieties, and therefore it can now be used to improve resistance to stripe rust in a broad set of varieties.

Susceptibility to black spot [caused by Mycosphaerella pinodes (Berk. and Blox.) Vestergr.] and weak stem strength in field pea (Pisum sativum L.) are major restrictions to yield, seed quality, and ease of harvest. Previous studies have established that additive genetic variance is present for both traits, and that stem strength is strongly associated with a field test of compressed stem thickness at the base of the stem. This study aimed to improve these two complex traits simultaneously by recurrent selection. Heritabilities and responses to selection for resistance to black spot and stem strength were evaluated during two cycles of recurrent selection after intercrossing diverse genotypes. Response to selection was indicated by a reduction of 10% in the mean black spot leaf disease in the [F.sub.2] of cycle 2 compared with the [F.sub.2] of cycle 1, when considered as a percentage of the mean of cycle 1 parents in the same trials. Likewise, there was a 15% increase in stem strength, based on the mean compressed stem thickness in the [F.sub.2] of cycle 2 compared with the [F.sub.2] of cycle 1. Broad sense heritability for resistance to black spot leaf disease was moderate (H = 0.63 [+ or -] 0.35 across cycles 1 and 2) and for compressed stem thickness was also moderate (H = 0.66 [+ or -] 0.34). Genetic gains were realized for both traits simultaneously in the first two cycles and were predicted to be rapid over the next five to six cycles based on a random mating quantitative genetics model.