Faba bean breeding for resistance against biotic stresses: Towards application of marker technology

Summary Faba beans are adversely affected by numerous fungal diseases leading to a steady reduction in the cultivated area in many countries. Major diseases such as Ascochyta blight (Ascochyta fabae), rust (Uromyces viciae-fabae), chocolate spot (Botrytis fabae), downy mildew (Peornospora viciae) and foot rots (Fusarium spp.) are considered to be the major constraints to the crop. Importantly, broomrape (Orobanche crenata), a very aggressive parasitic angiosperm, is the most damaging and widespread enemy along the Mediterranean basin and Northern Africa. Recent mapping studies have allowed the identification of genes and QTLs controlling resistance to some of these diseases. In case of broomrape, 3 QTLs explained more than 70% of the phenotypic variance of the trait. Concerning Ascochyta, two QTLs located in chromosomes 2 and 3 explained 45% of variation. A second population sharing the susceptible parental line also revealed two QTLs, one of them likely sharing chromosomal location and jointly contributing with a similar percentage of the total phenotypic variance. Finally, several RAPD markers linked to a gene determining hypersensitive resistance to race 1 of the rust fungus U. viciae-fabae have also been reported. The aim of this paper is to review the state of the art of gene technology for genetic improvement of faba bean against several important biotic stresses. Special emphasis is given on the application of marker technology, and Quantitative Trait Loci (QTL) analysis for Marker-Assisted Selection (MAS) in the species. Finally, the potential use of genomic tools to facilitate breeding in the species is discussed. The combined approach should expedite the future development of lines and cultivars with multiple disease resistance, one of the top priorities in faba bean research programs.     

An introduction to markers, quantitative trait loci (QTL) mapping and marker-assisted selection for crop improvement: The basic concepts

Recognizing the enormous potential of DNA markers in plant breeding, many agricultural research centers and plant breeding institutes have adopted the capacity for marker development and marker-assisted selection (MAS). However, due to rapid developments in marker technology, statistical methodology for identifying quantitative trait loci (QTLs) and the jargon used by molecular biologists, the utility of DNA markers in plant breeding may not be clearly understood by non-molecular biologists. This review provides an introduction to DNA markers and the concept of polymorphism, linkage analysis and map construction, the principles of QTL analysis and how markers may be applied in breeding programs using MAS. This review has been specifically written for readers who have only a basic knowledge of molecular biology and/or plant genetics. Its format is therefore ideal for conventional plant breeders, physiologists, pathologists, other plant scientists and students.     

Asset mapping and Whanau action research: ‘New’ subjects negotiating the politics of knowledge in Te Rarawa

Te Runanga o Te Rarawa is the tribal council representing the interests of the marae (tribal commons) and hapu (a subtribal kin group) that make up the iwi (a Maori tribe) of Te Rarawa in the far north of Aotearoa/New Zealand. In April 2005, officials approached us to help them secure a valuable funding stream tagged to marshalling resources for material development in the area. They sought curriculum vitae and assistance in reframing the funding specifications. Intrigued, armed with a conceptual toolkit drawn from Gibson‐Graham's ideas of post‐development and asset‐based community mapping, and confident that we could add value, we agreed to help. This paper examines the complex politics of our involvement and our changing positioning as researcher subjects. We argue that negotiating a politics of knowledge for projects of this nature requires engagement in complex representational politics of place and divisive identity politics that rage around it. There are no easy protocols for outside researchers, but with appropriate humility and sensitivity to these politics, we can rely on, and should stand up for, the value of our work, which lies in commitments to excellence in scholarship. We cannot and should not seek to control these politics, which will chew us up and spit us out – humanely and with good grace or otherwise. However, good academic work will recognise and adapt to them. In our particular case, we argue that our work had significant value; and in this paper, we trace the production of this value.