Variations in chromatin structure in host nuclei of a vesicular arbuscular mycorrhiza

Abstract

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.

First‐report of the inhibition of arbuscular mycorrhizal infection of Pisum sativum by specific and irreversible inhibition of polyamine biosynthesis or by gibberellic acid treatment

“…These results suggest that ODC may play a role in root growth and in arbuscular mycorrhizal development. It is known that arbuscular mycorrhizal colonization is accompanied by chromatin decondensation of the plant nucleus which indicates an increased transcriptional activity [28]. Polyamines stabilize nucleic acids [29], and are essential to steps in transcription and translation [30].…”

Nucleus size in the host cells of an Arbuscular Mycorrhizal system: a mathematical approach to estimate the role of ploidy and chromatin condensation

“…Nuclear hypertrophy has been reported several times as one of the cytological effects of mycorrhizal colonization (Protsenko and Shemanakova 1971;Holley and Peterson 1979;Carling and Brown 1982;Berta et al 1990). Nevertheless, observations were often only qualitative, data concerned at most only mean nuclear size, regardless of DNA content, and the cause of hypertrophy was not investigated in depth.…”

“…Nevertheless, observations were often only qualitative, data concerned at most only mean nuclear size, regardless of DNA content, and the cause of hypertrophy was not investigated in depth. The first reports excluded AM-induced polyploidization, therefore hypertrophy was considered a consequence of chromatin decondensation (Berta et al 1990;Sgorbati et al 1993) related to increased transcriptional activity Lingua et al 1999). More recent reports have shown that AM colonization can affect ploidy in two very different plants, like tomato and leek (Berta et al 2000;Fusconi et al in press).…”

Detection of symbiosis‐related polypeptides during the early stages of the establishment of arbuscular mycorrhiza between Glomus mosseae and Pisum sativum roots

“…Little is known about the molecular mechanisms by which genetic factors exert their influence on AM development. A higher transcriptional activity, as indicated by a decondensed chromatin of the host nucleus, follows AM infection (Berta et al, 1990). Investigations on gene regulation in endomycorrhiza were first focused on genes implicated in plant defence response (Harrison & Dixon, 1993;Volpin et al,1995;Blee & Anderson, 1996;Kapulnik et al, 1996).…”