Some Biochemical Changes Associated with Paclobutrazol-Induced Adventitious Root Formation on Bean Hypocotyl Cuttings

Phaseolus vulgaris hypocotyl cuttings were placed in solutionscontaining either 0 (controls) or 43 µM paclobutrazolfor 24 h after which they were placed in peat– perlitefor 8 d. Paclobutrazol more than doubled the number of rootsformed on the cuttings but did not affect individual root length.Compared with controls, treated cuttings exhibited increasedactivities of catalase, peroxidase, polyphenol oxidase, malatedehydrogenase, protease and RNase in the base of the cuttings.These enhanced enzyme activities were particularly evident between3 and 5 d after excision. The largest paclobutrazol-inducedpromotion of enzyme activity occurred with malate dehydrogenasewhich was increased more than 2-fold compared with the controls.In contrast, paclobutrazol reduced amylase activity in comparisonto controls, suggesting that this enzyme may not be directlyrelated to root formation. These data indicate that the enhancementof adventitious root formation by paclobutrazol is accompaniedby changes in the activities of a number of enzymes which havepreviously been postulated to be involved in rooting. However,these changes in activity are generally greatest later in therooting period, suggesting that they may be involved in thedevelopment rather than the initiation of roots. Enzyme activity, growth regulator, Phaseolus vulgaris L., rooting     

The adaptive significance of coloration in lagomorphs

Lagomorph pelage coloration was matched to habitat type, geographical region, altitude and behaviour to explore the adaptive significance of coloration patterns in this little-studied order of mammals. Analyses were conducted with and without taking phylogeny into account. The former analyses were based on a weighted, phylogenetic supertree for all extant species of lagomorphs that we constructed using morphological and molecular data from 146 papers in the literature. Although our analyses represent an initial, somewhat crude investigation, several clear trends are evident. First, overall body coloration across lagomorphs tends to match the background as shown for pale and red coloration and perhaps seasonal pelage change. The case for countershading being a method of concealment is far less strong. Second, ear tips appear to have a communicative role since they are conspicuous in many different habitats. Third, hypotheses for tail tips having a communicative role, for extremities being dark for physiological reasons, and for Gloger's rule received only partial support.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79, 309–328.