Genetic variability on seed yield and related traits of elite faba bean (Vicia faba L.) genotypes.

Faba bean is one of the most important cool season crops in the highlands of Ethiopia and the country is considered as the secondary center of diversity. This study was conducted at Haramaya, Boreda and Hirna districts of Eastern Hararghe from 2006 to 2008 cropping season using twenty five elite genotypes of faba bean to determine the extent and pattern of genetic diversity for seed yield and related traits. The treatments were arranged in a randomized complete block design with three replications. The data were subjected to the analyses of variance using the SAS program. The mean squares due to genotypes were highly significant for seed yield (p < 0.01) indicating the existence of sufficient genetic variability for seed yield. Mean squares due to the interaction between year and location were highly significant for all the traits studied (p < 0.01). High genotypic coefficient of variation (10093.53%) was observed for seed yield followed by number of seeds per plant (325.45%). The estimated values of phenotypic variances were in the range of 0.60 for number of seeds per pods to 196564.64 for seed yield. Genetic gains that expected from selecting the top 5% of the genotypes, as a percent of the mean, varied from 12.32% for number of seeds per plant to 35.46% for seed yield. The average linkage technique of clustering produced a more understandable portrayal of the 25 faba bean genotypes by grouping them into five clusters. The maximum distance was found between cluster three and five (D2 = 691.47). Thus, the materials tested in the entire experiment will be maintained for further breeding program.

Uptake and allocation of carbon and nitrogen in Vicia narbonensis plants with increased seed sink strength achieved by seed-specific expression of an amino acid permease.

Over-expressing an amino acid permease in Vicia narbonensis seeds increases sink strength for N that is evident from the higher seed protein content and seed weight. Here, the effect of increased seed sink strength of line AAP-12 on growth, development, and on whole plant carbon and nitrogen uptake and partitioning is analysed. AAP-12 plants have a prolonged growth period. Accumulation and partitioning of dry matter and N in leaves, stems, and pods are higher whereas remobilization to the seeds is delayed, indicating that the switch from growth to reserve allocation and remobilization is delayed. Measuring uptake and allocation of (15)N-ammonia applied via the roots revealed a higher and longer label uptake period during maturation. Measuring whole plant carbon fixation and allocation after (13)C labelling shows higher levels at maturation, particularly in seeds, indicating higher seed sink strength for C and increased allocation into maturing seeds. Levels of cytokinins were dramatically increased in AAP-12 seeds indicating its role in nitrogen-mediated growth stimulation. AAP-12 seeds have higher natural abundances for (13)C indicating increased C fixation via PEP carboxylase in order to meet the higher demand of carbon acceptors for amino acid synthesis. In summary, increased seed sink strength for N in AAP-12 stimulates seed growth, but also that of vegetative organs, which finally leads to a higher ratio of vegetative to seed biomass at maturity and thus a lower harvest index. Therefore, the increased N uptake due to higher seed demand of AAP-12 is partly compensated by growth stimulation of vegetative organs.

Monoclonal antibodies against the Tn-specific isolectin B4 from Vicia villosa seeds: characterization of the epitope of the blocking antibody VV34.

Vicia villosa isolectin B4 (VVLB4) recognizes the Tn antigen (GalNAc-O-Ser/Thr) exposed in certain human carcinomas. We have produced anti-VVLB4 monoclonal antibodies (MAbs), and their lectin recognition selectivity was assessed by ELISA and Western blot against the purified Gal/GalNAc-specific lectins from Vicia villosa, Salvia sclarea, Helix pomatia, Arachis hypogaea, Glycine max, and Dolichos biflorus. The antibodies were also tested for their ability to block the binding of VVLB4 to the Tn antigen expressed on immobilized asialo ovine submaxillary mucin. Two MAbs, VV34 and VV2, specifically recognized VVLB4 and impaired the binding of the lectin to the Tn antigen by 98% and 21%, respectively. On the other hand, MAbs VV1 and VV22 cross-reacted with other purified lectins. The four antibodies recognized native and periodate-oxidized nonreduced as well as reduced VVLB4 after SDS-PAGE and Western blot, suggesting that they were recognizing continuous polypeptide epitopes. The VV34 antibody recognized two tryptic peptides (7-29 and 96-106) from VVLB4, which are contiguous in the three-dimensional structure of the lectin. The minimum structural determinant of the epitope was mapped to the polypeptide stretch (18)LILQED(23) using a set of overlapping synthetic peptides. This region of the molecule encompasses the C-terminal part of the loop joining strands beta1 and beta2 and the N-terminal part of beta2, and is located about 20-25 A away from the center of the Tn-combining site.