Conventional and Molecular Breeding Tools for Accelerating Genetic Gain in Faba Bean (Vicia Faba L.)

Faba bean is a cool-season grain legume crop, which is grown worldwide for food and feed. Despite a decrease in area under faba bean in the past, the interest in growing faba bean is increasing globally due to its high seed protein content and its excellent ecological service. The crop is, however, exposed to diverse biotic and abiotic stresses causing unstable, low grain yield. Although, sources of resistance to main diseases, such as ascochyta blight (Ascochyta fabae Speg.), rust (Uromyces viciae-fabae (Pers.) Schroet.), chocolate spot (Botrytis fabae Sard.) and gall disease (Physioderma viciae), have been identified, their resistance is only partial and cannot prevent grain yield losses without agronomical practices. Tightly associated DNA markers for host plant resistance genes are needed to enhance the level of resistance. Less progress has been made for abiotic stresses. Different breeding methods are proposed, but until now line breeding, based on the pedigree method, is the dominant practice in breeding programs. Nonetheless, the low seed multiplication coefficient and the requirement for growing under insect-proof enclosures to avoid outcrossing hampers breeding, along with the lack of tools such as double haploid system and cytoplasmic male sterility. This reduces breeding population size and speed of breeding hence the chances of capturing rare combinations of favorable alleles. Availability and use of the DNA markers such as vicine-convicine (vc -) and herbicide tolerance in breeding programs have encouraged breeders and given confidence in marker assisted selection. Closely linked QTL for several biotic and abiotic stress tolerance are available and their verification and conversion in breeder friendly platform will enhance the selection process. Recently, genomic selection and speed breeding techniques together with genomics have come within reach to accelerate the genetic gains in faba bean. Advancements in genomic resources with other breeding tools, methods and platforms will enable to accelerate the breeding process for enhancing genetic gain in this species.

Is nitrogen accumulation in grain legumes responsive to growth or ontogeny?

Nitrogen (N) accumulation in legumes is one of the main determinants of crop yield. Although N accumulation from symbiotic nitrogen fixation or N absorption from the soil has been widely investigated, there is no clear consensus on timing of the beginning of N accumulation and the termination of N accumulation and the physiological events that may be associated with these two events. The analyses conducted in this study aimed at identifying the determinant of N accumulation in two grain legume species. Nitrogen accumulation dynamics and mass accumulation and development stages were recorded in the field for several genotypes of common bean (Phaseolus vulgaris) and faba bean (Vicia faba) under different growing conditions. This study showed that during the vegetative stages, N accumulation rate was correlated with mass accumulation rate. However, the maximum accumulation of N did not correspond to the time of the maximum mass accumulation. In fact, for both species, N accumulation was found to persist in seed growth. This challenges a common hypothesis that seed growth causes a decrease in N accumulation because of a shift of the photosynthate supply to support the seed growth. Even more surprising was the shift of the active accumulation of N in faba bean to late in the growing season as compared with common bean. N accumulation by faba bean only was initiated at high rates very late in vegetative growth and persisted at high rates well into seed fill.

Host differentiation and variability of Orobanche crenata populations from legume species in Morocco as revealed by cross-infestation and molecular analysis

BACKGROUND

Orobanche crenata represents a major biotic constraint to production of faba bean and lentil in Morocco. While this parasitic plant attacks both of these crops, the extent to which Orobanche biotypes specialise in parasitising specific crops is unknown. To address this question, we studied O. crenata that grew on different hosts and quantified their host specificity to faba bean and lentil. The virulence of O. crenata populations on each host was investigated through field trials, pot and Petri dishes assays. Genetic diversity of the parasite populations was also assessed through molecular analyses.

RESULTS

The two legume species showed distinct patterns of specificity. Faba bean was more susceptible to both O. crenata populations, while the specificity for lentil by lentil-grown O. crenata was evident at the final stage of the parasite life cycle as shown by correspondence factorial analyses. Considerable internal variation (81%) within O. crenata populations parasitising both legume species was observed by molecular analyses, but significant divergence (19%; Ø = 0.189; P = 0.010) among the populations was detected.

CONCLUSION

These results indicate that O. crenata can adapt to specific host species, which is important knowledge when developing integrated pest management practices for parasitic weed control. © 2017 Society of Chemical Industry.