Unusual plasties in an endomycorrhizal root

Abstract

Unusual plastids, identified as globular chromoplasts directly developed from proplastids, observed in the infected root cells of Ornithogalum umbellatum L. are tentatively interpreted as an expression of host reaction to fungus infection.

Reorganization of tobacco root plastids during arbuscule development

“…In mycorrhizal tobacco, mycorradicin (data not shown) and cyclohexenone (Maier et al 2000) have been observed. This mycorrhiza-induced accumulation of apocarotenoids, as well as the ultrastructural observations of Scannerini and Bonfante-Fasolo (1977) and Dexheimer et al (1988), possibly indicates that the role of plastids during the development of arbuscular mycorrhizas might not be restricted to basic metabolic pathways like fatty acid biosynthesis, nitrogen assimilation or starch deposition.…”

“…Because of several ultrastructural features, most notably the existence of a tubular network within the plastid stroma, Dexheimer et al (1990) speculated about the secretion of terpenoids as part of a plant defense reaction to the fungal colonization. Scannerini and Bonfante-Fasolo (1977) had already described large plastids containing lipophilic vesicles close to fungal arbuscules in mycorrhizal roots from Ornithogalum umbellatum L.. These plastids eventually lysed and released their vesicular contents into the cytoplasm; they were interpreted as chromoplasts due to the yellowish colour of the roots.…”

Arbuscular mycorrhizal fungi induce the non‐mevalonate methylerythritol phosphate pathway of isoprenoid biosynthesis correlated with accumulation of the ‘yellow pigment’ and other apocarotenoids

“…The AM‐induced activation of the plastid‐located MEP pathway may be related to these observations and to earlier reports on unusual plastids in mycorrhizal roots, which resemble chromoplasts and always occur close to fungal arbuscules ( Dexheimer et al . 1990 ; Scannerini & Bonfante‐Fasolo 1977). DXS and DXR transcript accumulation might be a marker for such a transition in root plastid development to parallel chromoplast formation for carotenoid biosynthesis specifically involved in AM physiology.…”

Vesicular-arbuscular mycorrhizas in white clover: a scanning electron microscope and X-ray microanalytical study

“…Phillips & Hayman (1970), , Ashford et al (1975), and Ebel et al (1958) have used sectioning and cytochemical techniques to reveal further details of endophyte morphology and to localise inorganic compounds associated with mycorrhizal infection. In addition, Scannerini & Bonfante-Fasolo (1977) and Kinden & Brown (1975 a, b) have used electron microscopy techniques, including thin sectioning and staining and scanning electron stereoscopy, to reveal much about fungal morphology and host-endophyte interaction. *The term "infection" is not used in this paper in the pathology sense to infer a disease condition.…”