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Bacterial leaf blight (BB), caused by the bacterium Xanthomonas oryzae pv. Oryzae (Xoo), is the major constraint amongst rice diseases in India. CSR-30 is a very popular high-yielding, salt-tolerant Basmati variety widely grown in Haryana, India, but highly susceptible to BB. In the present study, we have successfully introgressed three BB resistance genes (Xa21, xa13 and xa5) from BB-resistant donor variety IRBB-60 into the BB-susceptible Basmati variety CSR-30 through marker-assisted selection (MAS) exercised with stringent phenotypic selection without compromising the Basmati traits. Background analysis using 131 polymorphic SSR markers revealed that recurrent parent genome (RPG) recovery ranged up to 97.1% among 15 BCF three-gene-pyramided genotypes. Based on agronomic evaluation, BB reaction, aroma, percentage recovery of RPG, and grain quality evaluation, four genotypes, viz., IC-R28, IC-R68, IC-R32, and IC-R42, were found promising and advanced to BCF generation.

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A total of 310 Barley accessions collected from ICARDA, Lebanon and grown in Indian condition at ICARDA-IRP (India Research Platform), Amlaha, (M.P.) were analyzed for morphological and genetic variability using nine agro-morphological traits i.e. Plant height (cm), number of tillers per plant, days to heading, number of ear heads per pant, length of ear (cm), number of spikelets per earhead, number of grains per earhead, yield per plant (g), and 1000-grain weight (g). The highest coefficient of variation as a result of highest diversity among the genotypes were found for grains per earhead (37.5%), spikelets per earhead (37.5%), yield per plant (35.3%), tillers per plant (31.3%) and earhead per plant (31.2%). However, ear length (16.9%), days to heading (15.4%), 1000-grain weight (13.5%) and plant height (11.2%) have conributued less to diversity with lower cofficient of variation. In cluster analysis, all the characters were used to construct a distance matrix using the Euclidian coefficient, and used to generate dendrogram showing similarity among all the genotypes, distance coefficient ranged between 0 and 200 which reveal the genetic diversity among genotypes. These exotic accessions evaluated can be further used for primary or secondary introduction in Indian breeding program.

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Spot blotch or leaf spot, caused by Bipolaris sorokiniana (earlierHelminthosporium sativum) is the most common form of leaf blights of barley which appears in warmer and humid weather. The genetic studies for leaf blight in barley have concluded complex inheritance of leaf blight resistance at adult plant stage. Current Indian barley varieties are mostly susceptible to leaf blight under high input conditions and attempts have been made to introduce resistance for this fungal disease in Indian barley. In the present study, a set of 85 barley germplasm accessions under epiphytotic conditions were screened for leaf blight disease occurrence. Of these lines, 68 genotypes were found resistant, 7 were moderately resistant, 7 were moderately susceptible and 3 were found susceptible. The genotypes grouped as resistant were able to keep the disease level on the plant at very low level may be useful in developing mapping populations for QTL studies. The molecular markers reported for QTL regions of leaf blight resistance were used to screen these lines to validate their applicability in molecular studies for leaf blight in Indian conditions. Three molecular markers (Ebmac 705, Bmag 606 and Bmag 225) located on 3H genomic region of barley were found associated with leaf blight resistance during molecular screening. This suggests that the genomic region at 3H chromosome is significantly involved in inheritance of leaf blight resistance in Indian barley. This study may prove useful in selection of plant material and marker assisted selection for incorporating leaf blight resistance in Indian barley. Bilgic, H., Steffenson, B. J. and Hayes, P . M. (2005). Comprehensive genetic analysis reveals differential expression of seedling and adult plant resistance to spot blotch in populations of barley. Theor. Appl. Genet., 111:1238-1250. Bilgic, H., Steffenson, B. J., and Hayes, P . M. (2006). Molecular mapping of loci conferring resistance to different pathotypes of the spot blotch pathogen in barley. Phytopathology, 96:699-708.

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