Agriculture and Agri-Food Canada

About: Agriculture and Agri-Food Canada is a facility organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Soil water. The organization has 10921 authors who have published 21332 publications receiving 748193 citations. The organization is also known as: Department of Agriculture and Agri-Food.

Genomics of adaptation during experimental evolution of the opportunistic pathogen Pseudomonas aeruginosa.

Abstract: Adaptation is likely to be an important determinant of the success of many pathogens, for example when colonizing a new host species, when challenged by antibiotic treatment, or in governing the establishment and progress of long-term chronic infection. Yet, the genomic basis of adaptation is poorly understood in general, and for pathogens in particular. We investigated the genetics of adaptation to cystic fibrosis-like culture conditions in the presence and absence of fluoroquinolone antibiotics using the opportunistic pathogen Pseudomonas aeruginosa. Whole-genome sequencing of experimentally evolved isolates revealed parallel evolution at a handful of known antibiotic resistance genes. While the level of antibiotic resistance was largely determined by these known resistance genes, the costs of resistance were instead attributable to a number of mutations that were specific to individual experimental isolates. Notably, stereotypical quinolone resistance mutations in DNA gyrase often co-occurred with other mutations that, together, conferred high levels of resistance but no consistent cost of resistance. This result may explain why these mutations are so prevalent in clinical quinolone-resistant isolates. In addition, genes involved in cyclic-di-GMP signalling were repeatedly mutated in populations evolved in viscous culture media, suggesting a shared mechanism of adaptation to this CF–like growth environment. Experimental evolutionary approaches to understanding pathogen adaptation should provide an important complement to studies of the evolution of clinical isolates.

Effects of a soil fulvic acid on the growth and nutrient content of cucumber (Cucumis sativus) plants

Abstract: Cucumber (Cucumis sativus) plants were grown in Hoagland solution to which 20 to 2000 ppm of a soil fulvic acid (FA) were added. The addition of 100 to 300 ppm of FA produced highly significant increases in the growth and development of above and below ground plant parts, in the uptake of nutrient elements (N, P, K, Ca, Mg, Cu, Fe and Zn), and in the formation of numbers of flowers per plant. Effects of adding 500 and more ppm of FA were less beneficial.

Closing the gaps: phylogenetic relationships in the Brassicaceae based on DNA sequence data of nuclear ribosomal ITS region

Abstract: Sequence data from the nuclear encoded ribosomal internal transcribed spacer (ITS) region were used to determine monophyly of tribes, tribal limits, and tribal relationships of 96 so far unassigned or tentatively assigned genera (represented by 101 taxa/accessions) within the Brassicaceae. Maximum-parsimony and maximum-likelihood analyses of 185 ITS Brassicaceae sequences, which also included representatives of each of the 34 currently recognized tribes, supported the separate phylogenetic distinctness of these tribes and permitted the tribal assignment of all but 12 of the unassigned genera into tribal clades. The data support the recognition of eight new, well-resolved, uni- or oligogeneric tribes recognized herein as the Alyssopsideae [96% bootstrap support (BS); including the central and southwestern Asian Alyssopsis and Calymmatium], Asteae (100% BS; including the Mexican Asta), Eudemeae (97% BS; South American Brayopsis, Eudema, and Xerodraba), Kernereae (96% BS; European Kernera and Rhizobotrya), Notothlaspideae (100% BS; New Zealandic Notothlaspi), Oreophytoneae (100% BS; eastern African Oreophyton and southern European Murbeckiella), and Yinshanieae (100% BS; Chinese Yinshania), as well as the moderately supported Microlepidieae (75% BS; Australian Microlepidium and Carinavalva). Furthermore, the results fully support the recent findings that the tribes Schizopetaleae and Thelypodieae ought to be recognized as two distinct tribes instead of a single tribe, as well as provide some support for the re-establishment of the tribe Cremolobeae, bringing the total number to 44 tribes in the family. Nearly 92% (308) of the 336 genera in the family have been assigned to a tribe. The earlier-published Anastaticeae is taken here to replace the Malcolmieae.