Abstract In many cropping regions of the world, yield is limited by the availability of micronutrients, and mi- cronutrient-efficient cultivars provide a yield advantage. Traditional methods of testing cultivars for micronutrient efficiency are time-consuming and laborious. Molecular markers linked to loci controlling micronutrient efficien- cy will allow more rapid and efficient selection and in- trogression of these traits than is currently possible. Us- ing a pot-based bioassay and bulked segregant analysis of an F 2 population, we have identified several RFLPs (grouped distally on chromosome 4HS) linked to a locus for manganese efficiency in barley. This manganese effi- ciency locus has been designated Mel1. Pot bioassay analysis of intercrosses suggests that three useful sources of manganese efficiency are likely to be allelic at the Mel1 locus. Field evaluation of marker selected F 4 prog- eny supports the major role of Mel1 in the genetic con- trol of manganese efficiency. Adoption of marker assist- ed selection for this trait in the Southern Australian bar- ley breeding program has occurred. This has been facili- tated by the demonstration that the Mel1 allele of Amagi Nijo can be distinguished from 95 other locally useful varieties and breeder’s lines on the basis of RFLPs iden- tified by just two molecular markers. Key words Barley · Manganese efficiency · RFLP mapping · Marker-assisted Selection · Plant nutrition · 4HS Introduction Manganese (Mn) deficiency in cereals grown on alkaline calcareous soils is a problem affecting a large portion of the cropping area of southern Australia and elsewhere in the world. On these soils manganese, although present, is usually in a complex plant-unavailable form (Marschner 1988). Plants that are deficient in manganese appear chlorotic as manganese has a major role in photosynthet- ic oxygen evolution. Manganese-deficient plants grow poorly and consequently yield poorly. Additionally, these plants are more susceptible to damage by diseases, such as take-all caused by the root fungal pathogen Gaeumannomyces graminis var. tritici (Wilhelm et al. 1988). Manganese deficiency is difficult to overcome by the addition of manganese-supplemented fertilizers at sowing as the added manganese is quickly converted to an unavailable form (Reuter et al. 1973). Foliar applica- tions of manganous sulphate are more effective, espe- cially if applied several times during the growing season, but this comes at a significant cost. Manganese-efficient cultivars are able to reach their yield potential on manganese deficient soils without man- ganese supplementation (Graham 1988). The exact physi- ological basis of manganese efficiency in cereals (or any other crop) grown on calcareous soils has not yet been elucidated, although several possibilities have been tested (Huang et al. 1994; Webb 1994; Marschner 1988). It ap- pears that efficient cultivars, compared to inefficient ones, are able to take up more manganese from these soils, rath- er than being able to make more efficient use of a low amount of manganese within the plant (Graham 1984; Graham et al. 1985). Expression of the efficiency trait can vary depending on a number of factors, such as tempera- ture and soil batch in pot tests and time of sowing and rainfall in the case of field trials. Manganese efficiency is not expressed in solution culture (Huang et al. 1994). Genotypic variation exists within barley for manga- nese efficiency (Graham 1988), with some cultivars, such as Amagi Nijo and Weeah, being very manganese- efficient. Earlier genetic studies of the manganese effi- Communicated by J. Dvorak M.A. Pallotta ( ✉ ) · R.D. Graham · P. Langridge · D.H.B. Sparrow Department of Plant Science, The University of Adelaide, Waite Campus, Urrbrae, South Australia, Australia 5064 Fax: +61 8 8303 7109 e-mail: margaret.pallotta@adelaide.edu.au S.J. Barker Faculty of Agriculture, The University of Western Australia, Nedlands, Western Australia, Australia 6907 Theor Appl Genet (2000) 101:1100–1108 © Springer-Verlag 2000 ORIGINAL ARTICLE M.A. Pallotta · R.D. Graham · P. Langridge D.H.B. Sparrow · S.J. Barker RFLP mapping of manganese efficiency in barley Received: 20 October 1999 / Accepted: 18 February 2000