Comparisons of alpha-amylase inhibitors from seeds of common bean mutants extracted through three phase partitioning

This study compared the inhibitory activity of alpha-amylase inhibitor (alpha AI) extracted from common bean (Phaseolus vulgaris L) variety Hwachia, its nine mutants and two introduced varieties by using three-phase partitioning (TPP). A commercially prepared Phase 2 was also used to serve as a comparative reference. The optimal purification parameters for TPP were 30% saturation ammonium sulphate and pH 5.25. Considerable variations were detected in alpha AI content, total inhibitory activity and specific inhibitory activity of alpha AI purified from different common beans. Mutant SA-05 had the alpha AI inhibitory activity of 6267 units g(-1) dry seed weight, which was higher than Hwachia (5062 units g(-1) dry seed weight) and Phase 2 (3200 units g(-1) dry weight). Moreover, it had an extremely lower IC(50) (0.40 mu g) than Phase 2 (10.22 mu g). Thus, the mutant SA-05 may be used as raw material in commercial preparation of alpha AI extracts for controlling appetite and energy intake. (C) 2011 Elsevier Ltd. All rights reserved

Allelopathic effects of bracken fern (Pteridium aquilinum L. Kuhn) in Taiwan

Field surveys in summer and winter seasons showed that both the plant population and cover (%) of weed plants in fern-growing areas were lower than in areas without fern (Pteridium aquilinum L. Kuhn), showing the allelopathic effects of this fern. Hence, its allelopathic effects were studied. In bioassays, the water extracts of fern fronds and rhizomes, especially the fronds, showed persistent and higher allelopathic effects (inhibition of seed germination, hypocotyl and radicle elongation) in many vegetables, than water extracts of litter and soils around the fern plant. This phenomenon was observed throughout one year and may partly explain the long-term allelopathic effects of this fern In situ. The water-soluble allelochemicals significantly inhibited the mitosis of radicle tip cells in radish. These allelochemicals at low rates (6%, w/v), kept high proportion of cells under division in prophase, while at the highest rate (25%) tested, the cell division was completely maintained at prophase. The allelopathic effect of water extract of bracken fern was confirmed and an interruption in plant cell cycle might be involved in the mechanism of action

Genetic diversity in NaN3-induced common bean mutants and commercial varieties detected by AFLP

The analysis of Amplified Fragment Length Polymorphism (AFLP) was used to estimate genetic diversity in common bean (Phaseolus vulgaris L.) variety Hwachia and in 34 NaN3-induced mutants and 11 commercial varieties introduced from China. Eight primer combinations generated 516 DNA fragments of the tested mutants and introduced varieties, of which 448 fragments were polymorphic. The calculated Jaccard similarity coefficients based on AFLP data ranged from 0.47 to 0.84. The molecular profiles obtained from eight AFLP primer pairs indicated a high genetic diversity among Hwachia, NaN3-induced mutants and introduced varieties. The extent of genetic variation was slightly higher between Hwachia and NaN3-induced mutants than between Hwachia and introduced commercial varieties. These results, supported by cluster analysis, suggest that NaN3-induced mutagenesis effectively broadens the genetic diversity of common bean varieties. Some of the produced mutants could be useful as sources of variation to develop new improved common bean varieties