Biomolecules as host defense weapons against microbial pathogens.

Antimicrobial peptides have been considered a new source of biomolecules in several fields of research/innovative applications: they would adjust to an ideal behavior seeking to overcome clinician, microbiological, human-animal-plant-environmental concerns. Antimicrobial peptides can be considered as ancient weapons found in living organisms suggesting they have played a fundamental role in his successful co-evolution with pathogens. Acting on microorganism membrane or having intracellular targets, they can also act as effectors of the innate immune response resulting on non-specific mechanisms of action. Two elements have speeded the research on pathogen control alternatives: a verified increase of antibiotic resistance and the relevance of finding amenable environmental compounds in plant health. As a result of its importance, great efforts have been accomplished to find, characterize, combine and synthesize effective antimicrobial peptides. This review intends to emphasize the generation of biomolecules, whether native or synthetic analogues, that have been matter of recent patents. Development of biomolecules suitable for therapeutic scopes and agricultural use have several challenges such as intrinsic toxicity, in vivo stability and suitable formulation contemplating the cost of production. Thus, biotechnological procedures using microbial systems or transgenic crops as plant factories might help to solve these challenges.

Genetic diversity and DNA content of three South American and three Eurasiatic Trifolium species

Six species of Trifolium (T. polymorphum Poir., T. riograndense Burkart, T. argentinense Speg., T. medium L., T. pratense L. and T. repens L.) were analyzed using inter-simple sequence repeats (ISSR) markers. Six selected primers generated 186 polymerase chain reaction (PCR) products exploring 112 loci in 34 genotypes analyzed with molecular sizes ranging from 200 to 1300 bp. These primers were able to discriminate among and within species, with the PCR products being on average 41.6 percent species-specific and 59.9 percent polymorphic at the within species level. Nuclear DNA content was determined by flow cytometry and revealed variation among species. The 1Cx genome size values were calculated and were found to range from 0.46 pg (T. pratense) to 0.96 pg (T. polymorphum). Genome size values of South American species were higher than those of Eurasiatic origin. The analyses of the molecular data grouped the six species in agreement with their geographical origin and clearly differentiate T. polymorphum from T. argentinense. The Eurasiatic group showed the highest average of species-specific bands (45.3 percent) and the South American group exhibited the highest amount of total bands (59.7). The highest level of intra-species polymorphisms was detected in T. argentinense (92.9 percent), followed by T. medium (89.5 percent).