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Utilization of “hidden genes” from wild species has emerged as a novel option for enrichment of genetic diversity for productivity traits. In rice we have generated more than 2000 lines having introgression from ‘A’ genome-donor wild species of rice in the genetic background of popular varieties PR114 and Pusa44 were developed. Out of these, based on agronomic acceptability, 318 lines were used for developing rice hybrids to assess the effect of introgressions in heterozygous state. These introgression lines and their recurrent parents, possessing fertility restoration ability for wild abortive (WA) cytoplasm, were crossed with cytoplasmic male sterile (CMS) line PMS17A to develop hybrids. Hybrids developed from recurrent parents were used as checks to compare the performance of 318 hybrids developed by hybridizing alien introgression lines with PMS17A. Seventeen hybrids expressed a significant increase in yield and its component traits over check hybrids. These 17 hybrids were re-evaluated in large-size replicated plots. Of these, four hybrids, viz., ILH299, ILH326, ILH867 and ILH901, having introgressions from O. rufipogon and two hybrids (ILH921 and ILH951) having introgressions from O. nivara showed significant heterosis over parental introgression line, recurrent parents and check hybrids for grain yield-related traits. Alien introgressions were detected in the lines taken as male parents for developing six superior hybrids, using a set of 100 polymorphic simple sequence repeat (SSR) markers. Percent introgression showed a range of 2.24 from in O. nivara to 7.66 from O. rufipogon. The introgressed regions and their putative association with yield components in hybrids is reported and discussed. [ABSTRACT FROM AUTHOR]

The Ug99 group of stem rust races ( Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn.) has evolved and migrated. While the original variant overcame the widely deployed gene Sr31, and Sr21 (in Chinese Spring background), but not Sr21 in Einkorn, a new strain of Ug99, virulent on Sr24, was detected in 2006 and caused a severe epidemic in 2007 in Kenya. Forms virulent on Sr36 and Sr21 were identified in 2007. Likewise, an Ug99 variant virulent to both Sr21 and Sr24 was identified in 2008 in Kenya. Simultaneously, the original strain spread to Yemen and Sudan in 2006. Fears of a spread into Asia were confirmed when this race was detected in Iran in 2007. This has raised serious concerns that Ug99 could follow the same migratory route from Africa to Asia as Yr9 and cause major epidemics across the epidemiological region of South Asia. In 2005-06, screening in Kenya and Ethiopia of wheat materials from Asian countries revealed a very low frequency of lines resistant to Ug99 and its variants. Under the umbrella of the Borlaug Global Rust Initiative ( BGRI), significant efforts have been made to counter the challenges posed by Ug99 and its derivative races. Diverse sources of resistance to the pathogen have been identified and incorporated in high-yielding wheat backgrounds. The most promising strategy has been to deploy spring wheat varieties possessing adult plant resistance ( APR) in infested and bordering areas to decrease inoculum amounts and slow down the development of new virulence, for example four CIMMYT genotypes with Sr2+ have been released in Afghanistan and their seed is also distributed in region bordering Iran. For an immediate remedy, race-specific resistance genes can be deployed in combinations using marker-assisted selection. Several Ug99-resistant varieties have already been released in South Asian countries ( Afghanistan, India, Nepal, Bangladesh and Pakistan), and seed dissemination is underway. The Ug99 risk in the region can be reduced to minimum levels by identifying, releasing and providing seed of high-yielding and resistant cultivars. [ABSTRACT FROM AUTHOR]

Background: Stripe rust, leaf rust, tan spot, and Karnal bunt are economically significant diseases impacting wheat production. The objectives of this study were to identify quantitative trait loci for resistance to these diseases in a recombinant inbred line (RIL) from a cross HD29/WH542, and to evaluate the evidence for the presence loci on chromosome region conferring multiple disease resistance. Methodology/Principal Findings: The RIL population was evaluated for four diseases and genotyped with DNA markers. Multi-trait (MT) analysis revealed thirteen QTLs on nine chromosomes, significantly associated with resistance. Phenotypic variation explained by all significant QTLs for KB, TS, Yr, Lr diseases were 57%, 55%, 38% and 22%, respectively. Marginal trait analysis identified the most significant QTLs for resistance to KB on chromosomes 1BS, 2DS, 3BS, 4BL, 5BL, and 5DL.Chromosomes 3AS and 4BL showed significant association with TS resistance. Significant QTLs for Yr resistance were identified on chromosomes 2AS, 4BL and 5BL, while Lr was significant on 6DS. MT analysis revealed that all the QTLs except 3BL significantly reduce KB and was contributed from parent HD29 while all resistant QTLs for TS except on chromosomes 2DS.1, 2DS.2 and 3BL came from WH542. Five resistant QTLs for Yr and six for Lr were contributed from parents WH542 and HD29 respectively. Chromosome region on 4BL showed significant association to KB, TS, and Yr in the population. The multi environment analysis for KB identified three putative QTLs of which two new QTLs, mapped on chromosomes 3BS and 5DL explained 10 and 20% of the phenotypic variation, respectively.Conclusions/Significance: This study revealed that MT analysis is an effective tool for detection of multi-trait QTLs for disease resistance. This approach is a more effective and practical than individual QTL mapping analyses. MT analysis identified RILs that combine resistance to multiple diseases from parents WH542 and/or HD29. [ABSTRACT FROM AUTHOR]

Induction of carbohydrate metabolism in relation to leaf blight (Bipolaris sorokiniana) was studied in healthy and infected leaves of barley (Hordeum vulgare). Two genotypes with varying sensitivity to leaf blight viz. PL 426 (susceptible) and BL 4 (resistant) in the absence of or following infection with leaf blight at different stages (0-20 days after infection) were used. Both acid and neutral invertase activities increased in response to leaf blight and might be linked with a defence mechanism against fungal infection. Low activities of sucrose synthase and sucrose phosphate synthase in infected leaves as compared to non infected leaves may be involved in retention of more sugars for utilization by the fungus for its own metabolic processes. The levels of total sugar, non-reducing sugar and starch were less in infected leaves as compared to non infected leaves. Irrespective of cultivar and stage of infection, activity of total amylase marginally increased with concomitant decline in starch content. The lower yield of infected host plants may be linked to reduced photosynthesis due to leaf blight leading to an alteration in the fluxes of carbon. Thus fungal infection represents a costly stress to the plant in terms of carbon production and utilization. [ABSTRACT FROM AUTHOR]