Legumes for grazing and health: the case of bituminaria bituminosa

Abstract

Legumes have been used for centuries for different purposes as human food (grain legumes such as lentils, chickpeas, etc.), animal feed (pasture and forage legumes) and as sources of secondary metabolites with health, medical or nutraceutical benefits (pharmaceuticals, cosmetics and chemicals). Due to this relevance, some of these species are the subject of breeding programmes for selecting hybrids with desirable traits. To aid in these programmes, Plant Biotechnology offers multiple methods for conservation and commercial propagation of valuable plants for different objectives, such as the pharmaceutical industry or pasture production. Bituminaria bituminosa (L.) C.H. Stirton (syn. Psoralea bituminosa L., Fabaceae, Psoraleeae; Stirton 1981) is a perennial legume widely distributed in the Mediterranean Basin and Macaronesia. The plants are grazed by small herbivores, but are mainly used for hay to feed milking goats, mostly in the Canary Islands. Moreover, B. bituminosa plants are a source of secondary metabolites of pharmaceutical and medicinal interest, such as furanocoumarins (FCs, psoralen and angelicin) and pterocarpans (bitucarpin A and B). So, their possible physiological functions and pharmacological properties are being analysed. Our research group began to search for alternative perennial pasture legumes for low-rainfall Mediterranean environments at the end of the 1980‘s. B. bituminosa showed desirable traits (tolerance to cold and/or drought), that draw it as a good option. So, the first step was to select new germplasm with different traits to increase genetic variability for starting a breeding programme, with the most promising varieties, accessions and natural hybrids to deliver cultivars in the minimum time. To achieve this objective, conventional crossing between cultivars and wild accessions, and techniques for interspecific crossing breeding were carried out, in order to obtain new hybrid lines with a combination of desirable traits. Then, for a commercial approach, studies based on seed production of B. bituminosa selected cultivars have to be carried out and also research on the alternative uses of this species, based on its content of bioactive components with pharmaceutical potential. As a result of this breeding programme, our research group has selected several hybrid and non-hybrid lines showing high levels of expression of, or a combination of desirable traits such as high forage quality, tolerance to biotic or abiotic stresses, or high contents of FCs. Therefore, the development of biotechnological tools such as micropropagation or in vitro plant regeneration protocols allowed the possibility of selecting somaclonal variants, obtaining pollen-derived haploid plants for optimising plant breeding programmes, and regenerating genetically transformed plants to control the biosynthesis of FCs. Moreover, these techniques offer attractive approaches for the large-scale propagation and conservation of germplasm resources of these plants. In the present chapter, we describe this species, show its potential uses and the strategies that may be followed to carry out a traditional breeding programme in B. bituminosa and the tools developed to assist in it.