Arbuscular mycorrhizal colonization in field-collected terrestrial cordate gametophytes of pre-polypod leptosporangiate ferns (Osmundaceae, Gleicheniaceae, Plagiogyriaceae, Cyatheaceae)

Abstract

To determine the mycorrhizal status of pteridophyte gametophytes in diverse taxa, the mycorrhizal colonization of wild gametophytes was investigated in terrestrial cordate gametophytes of pre-polypod leptosporangiate ferns, i.e., one species of Osmundaceae (Osmunda banksiifolia), two species of Gleicheniaceae (Diplopterygium glaucum, Dicranopteris linearis), and four species of Cyatheales including tree ferns (Plagiogyriaceae: Plagiogyria japonica, Plagiogyria euphlebia; Cyatheaceae: Cyathea podophylla, Cyathea lepifera). Microscopic observations revealed that 58 to 97% of gametophytes in all species were colonized with arbuscular mycorrhizal (AM) fungi. Fungal colonization was limited to the multilayered midrib (cushion) tissue in all gametophytes examined. Molecular identification using fungal SSU rDNA sequences indicated that the AM fungi in gametophytes primarily belonged to the Glomeraceae, but also included the Claroideoglomeraceae, Gigasporaceae, Acaulosporaceae, and Archaeosporales. This study provides the first evidence for AM fungal colonization of wild gametophytes in the Plagiogyriaceae and Cyatheaceae. Taxonomically divergent photosynthetic gametophytes are similarly colonized by AM fungi, suggesting that mycorrhizal associations with AM fungi could widely occur in terrestrial pteridophyte gametophytes.

Pteridophyte fungal associations: Current knowledge and future perspectives

“…However, in a second marattioid genus, Ptisana , the gametophyte fungus is a member of the Diversisporaceae (Rimington et al, ). In all three genera the distribution and morphology of the fungi in the ventral midrib region of the cordate gametophytes mirrors that in many thalloid liverworts (Ligrone et al, ) and is repeated throughout the leptosporangiate ferns (Ogura‐Tsujita et al, ). Widely different sporophyte and gametophyte morphologies now rest comfortably with the recent placement of horsetails (Equisetales) as sister to all other monilophytes (Knie et al, ) rather than as a sister clade to the Marattiaceae (Pryer et al, ).…”

“…Most studies on wild fern gametophytes have focused on their ecology and reproductive biology (Farrar et al, ), with the difficulty of identifying these down to the species or even genus level (Farrar, ) further contributing to the lack of data on fungi. Whatever the present gaps in overall coverage of the ferns, two features do appear to be constant: rhizoids are the major routes of fungal entry and bona fide symbionts are invariably present in the ventral cell layers in the central cushion region, but are much less frequent in the unistratose wings (Ogura‐Tsujita et al, , ).…”

“…Extending their morphological and molecular study on Angiopteris and Osmunda (Ogura‐Tsujita et al, ) to a range of pre‐Polypodiales leptosporangiate ferns to include two species in the Gleicheniales and four in the Cyatheales, Ogura‐Tsujita et al () found that not only were 58%–97% of the gametophytes colonized by AM fungi but that these also belonged to a wide range of Glomeromycota fungi. In addition to Glomeraceae, they also found members of the Claroideoglomeraceae, Gigasporaceae, Acaulosporaceae, and Archaeosporales fungi previously unknown in ferns but which are widespread in thalloid liverworts and hornworts (Bidartondo et al, ; Desirò et al, ; Field et al, 2015b).…”

Micorriza arbuscular, Mucoromycotina y hongos septados oscuros en helechos y licófitas con distribución en México: una revisión global

“…Para un tener un panorama completo de las interacciones gametofito-hongo en el ciclo de vida de los helechos y licófitas, hay que tener en cuenta los tipos de ambientes donde se desarrollan las especies. Estudios recientes, confirman la presencia de micorriza arbuscular en gametofitos cordados de helechos, que crecen al interior de un bosque subtropical perennifolio en Japón (Ogura-Tsujita et al, 2015). Por el contrario, gametofitos de las especies Pteris vittata y Nephrolepis exaltata, consideradas como especies pioneras, demuestran que no son susceptibles a la colonización por HMA, formando micorriza únicamente en el esporofito diploide (Lloyd, 1974;Bonfante & Selosse, 2010;Wang et al, 2012;Muthukumar & Prabha 2012).…”

“…Por el contrario, gametofitos de las especies Pteris vittata y Nephrolepis exaltata, consideradas como especies pioneras, demuestran que no son susceptibles a la colonización por HMA, formando micorriza únicamente en el esporofito diploide (Lloyd, 1974;Bonfante & Selosse, 2010;Wang et al, 2012;Muthukumar & Prabha 2012). Las herramientas moleculares pueden ayudarnos en la identificación taxonó-mica de las especies de hongos que colonizan tanto a gametofitos como a helechos y licófitas (Pryer et al, 2004;Ogura-Tsujita et al, 2015). Para tal fin, una alternativa sería implementar estudios experimentales obteniendo gametofitos a partir de la siembra de esporas (Turnau et al, 2005;Lara-Pérez, 2007;Reyes-Jaramillo et al, 2008).…”