S U M MARYMorphometric at-ialysis, modelling and histological techtitques were used to study root morphogenesis in nonmycorrhizal and mycorrhizal plants of Allium porrum infected by a Glomus sp., strain Eg, during the first 105 days after sowing. They showed that morphogenetic changes were induced by the fungus in the root system of the host.Adventitious roots of mycorrhizal plants becan-ie more numerous and shorter than those of eontrols, as mycorrhizal infection proceeded. Increase in number vvas fitted by logistic curves in myeorrhizal and control plants; increase in length vvas fitted in both cases by logistic curves. Myeorrhizal roots became progressively more branched than controls: branching increased linearly with time in mycorrhizas, whereas in the controls it showed an almost constant frequency from day 49 onwards and was fitted by a logistic curve. There vvas a significant depression of mitotic index demonstrated in the apical meristems of vesieular-arbiiseular n-iyeorrhizas.
Summary• Here peppermint growth and terpene production of in vitro generated plants ( Mentha piperita ) in response to inoculation with a leaf fungal endophyte were characterized.• Peppermint plants were studied by means of morphometric, biochemical and image analysis, employing both in vitro and in pot cultures. Leaf essential oils were analysed by gascromatography-mass spectrometry.• The endophyte induced profound effects on the growth of peppermint, which responded with taller plants bearing more expanded leaves. The observed increase of leaf dry matter over leaf area suggested a real improvement of peppermint metabolic and photosynthetic apparatus. Root architecture was of the herring-bone type, showing greater dry biomass percentage over the total. A sustained lowering of (+)-menthofuran and an increase of (+)-menthol percentage concentrations were found in plants from both in vitro and pot cultures.• The study represents the first report on specialized endophytic fungi in peppermint green tissues and highlights some of the principal morphological and biochemical aspects of this mutualism. Effects exerted on plant growth and essential oil production in peppermint suggest further biotechnological applications.
Electron microscopy is a powerful tool in understanding functional mechanisms in symbiosis (i.e., recognition and transfer of nutrients between partners), but mycorrhizal associations are not yet so well known as host–pathogen and host – mutualistic bacterial associations. However, the study of mycorrhizal ultrastructure has provided some interesting information. In fact unknown symbionts can be recognized with electron microscopy and mycorrhizae can be classified according to a sequence linking intercellular and intracellular interactions between host and fungus. General conclusions can be drawn from this ultrastructural sequence. (i) The most significant cytological feature in mycorrhizae is the presence of an interface through which partners communicate along a vast surface area. This is the key area for symbiotic interactions (both recognition and nutrient transfer) and can vary a great deal mostly in intracellular interactions. (ii) The ultracytochemical aspects of those interfaces, mostly as regards the components of the interfacial matrix, appear quite different from those of host–pathogen associations and suggest a compatibility mechanism. (iii) As regards the transfer of nutrients, even though it has been claimed that transfer of nutrient in all intracellular interactions is achieved by a digestion mechanism of the fungus by the host, available ultrastructural data are not consistent with this hypothesis.
Puya raimondii Harms is an outstanding giant rosette bromeliad found solely around 4000 m above sea level in the Andes. It flowers at the end of an 80 - 100-year or even longer life cycle and yields an enormous (4 - 6 m tall) spike composed of from 15,000 to 20,000 flowers. It is endemic and currently endangered, with populations distributed from Peru to the north of Bolivia. A genomic DNA marker-based analysis of the genetic structure of eight populations representative of the whole distribution of P. raimondii in Peru is reported in this paper. As few as 14 genotypes out of 160 plants were detected. Only 5 and 18 of the 217 AFLP marker loci screened were polymorphic within and among these populations, respectively. Four populations were completely monomorphic, each of the others displayed only one to three polymorphic loci. Less than 4 % of the total genomic variation was within populations and genetic similarity among populations was as high as 98.3 %. Results for seven cpSSR marker loci were in agreement with the existence of a single progenitor. Flow cytometry of seed nuclear DNA content and RAPD marker segregation analysis of progeny plantlets demonstrated that the extremely uniform genome of P. raimondii populations is not compatible with agamospermy (apomixis), but consistent with an inbreeding reproductive strategy. There is an urgent need for a protection programme to save not only this precious, isolated species, but also the unique ecosystem depending on it.
SUMMARYMicroHuorimetric and flow cytometric analyses were used in nuclei of cortical cells of roots in the endomycorrhizal system Allium porrum L. + a Glomus sp., strain E., (from Rothamsted Station), in an attempt to explain nuclear hypertrophy. No variation of DNA content in comparison with the controls was observed in mycorrhizal roots. An increase of fluorescence (about 25 "o) vvas observed in mycorrhizal root nuclei stained with an undersaturating concentration of DAPI. This can be explained by a greater accessibility of DNA to Huorochromes owing to a lower degree of chromatin condensation, as confirmed by ultrastructural data.Our results suggest a possible explanation of nuclear hypertrophy and, further, show that variations of chromatin condensation can occur in mature plant cell nuclei, even though this, in differentiated plant cells, is generally considered to be independent of the cellular functions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.