b i o l o g y Biol. Lem. (2011) 7,54 577 letters doi:10,1098/rsbl 2010, 1203 Prb

Question

b i o l o g y Biol. Lem. (2011) 7,54 577 letters doi:10,1098/rsbl 2010, 1203 Prblished online 9 March 20 Evolutionary biology The dawn of symbiosis between plants and fungi Martin Bidartondo David J. Read 34, 5.6 Vincent Merckx James M. Trappe Roberto Ligronee and Jeffrey G. Duckett Biology, Imperial College London, London SW7 24Z, UK Animal and Psanr Science, Unitersity of Shaniela, Sheffield S10 2TN, UK Panr Biolog, Unitensiry Western Australia, Pernhl Western Ausmaila 6009, Australia Forer Science, Oregon State Unitersity, Cornalis, OR 91331, USA OCSIRO Canberra, Ausmaiian Capiral Territory 2601, Asestealia Nenherlands Centre for Bioditersiy Naturalis, 2300RA Leiden The Netherlands Scienze Ambienzali, Seconda Unibenita di Napoli, 81109 Cauerta, Italy Botany, Natuural Histary Museum, London SW7 5BD, UK *Author for correspondence (mbidarnondo@imperialae.uk) The colonization of land by plants relied on fun damental biological innovations among which was symbiosis with fungi to enhance nutrient ptake. Here we present evidence that several species represe nting the earliest groups of land plants are symbiotic with fungi ofthe Mucoromy- cotina. This finding brings up the possibility that terre n was facilitated by these fungi rather than as conventionally proposed, members of the e Glomeromycota Since the 1970s it has been assumed, largely from the observation that vascular plant fossils of the early Devonian (400 Ma show arbuscule-like structures, that fungi of the Glomeromycota were the earliest to form mycorrhizas, and evolutionary trees have until now, placed Glomeromycota as the oldest known lineage of endomycorrhizal fungi. our observation that Endogone-like fungi. are widely associated with the earliest branching land plants, and give way to gl omeromycotan fungi in later lineages raises the new hypothesis that members of the Mucoromycotina rather than the Glomeromy cota enabled the establishment and growth of early land colonists Keywords: ecology; evolution; palaeobiology; mutualism; mycorrhizal; liverwort INTRODUCTION The idea that symbiosis with arbuscular mycorrh izal fungi (Glomeromycota) allowed rootless early plants to invade poorly developed primaev al soils lij and go on to transform the biosphere has gained increasing widespread acceptance 12-5 helped some fossil support [6,7) and the absence of any plausible alterna- tives. In other words, arbuscular mycorrhizal fungi a the most common. fungi forming endomycorrhizal e. intracellular) mutualisms with today's vascular plants and these are also the most ancient Electronic supplementary material is available at http://dxdoi org/ 0.1098 /rsbl.2010.1203 or via http://rsbl royalsocietypublishing, org. end omy corrhizal fungi known to date. Thus, the assumption that Glomeromycota were involved in the colonization of land by plants has not been con tested, arbuscular mycorrhizas are regarded as the mother of plant root endosymbioses' 18], and methods that only detect Glomeromycota are routinely used in molecular ecological studies of mycorrhizal plants. Curiously, analyses of the earliest branching lineages of land plants (i liverworts, Marchantio- phyta 19 have so far revealed only symbioses with the most recently branched lineage of the Glomeromy. e. Glomerales) or with even cota recent lineages of Bas diomycota and Ascomycota 10 Because the plant taxon sam pling available in previous studies was ly limited and some of the plant fungal symbiotic morphologies observed in the earliest branching lineage of liverworts (i e. Haplomitriopsida [11]) are considered unusual [12,13], e investigated the associations of diverse 'lower plants to test whethe are symbiotic with other ancient fungal lineages. 2. MATERIAL AND METHODS Specimens At each of 25 sites, we collected one to two colonies (less than 5 cm diameter) of each species of lower plant. Each collection was sub sampled within a week g 5-10 thalli or stems. These were cleaned with forceps and rinsed in distilled water. Fungal fruit- bodies were obtained from oregon State University Herb Plant vouchers are in the herbarium of the Natural History Museum. Plant nomenclature follows the latest schem (b) Fungal detection ns were prepared for scanning and transmission electron microscopy as detailed elsewhere 2,13). For molecular analysis healthy colonized apical 2-3 mm length of plant or a 1-2 mm ent of fungal fruitbody placed in 300 ul of lyis buffer, stored at 80 C, and subsequently used for a genomi DNA as described elsewhere [15] with a purification step using GeneClean QBioGene). Glemeromycota nrDNA pri 70 failed to am plify ples, thus we used the fungal nuclear ribosomal small subunit NSi/ER3 primer set 8,191 for all sam and the translation clongation factor EF1-983f EF-2218r primer set and nuclear ribosomal internal transcribed spacer large subunit ITS1F/LR7 primer set 8,2 representative non-Glomeromycota saml ples. These regions were amplified gumpStart, Sigma), cloned (TOPO TA nvitrogen) and four to eight clones sequenced (BigDye v. 3 on ABI3730 Genetic Analyzer, Applied Biosys Representative DNA sequences are deposited in GenBank JF414136-JF41 4235) (c) Phylogenetics Maximum parsimony an erformed using PAUP were v. 4.0b10 [22] for heuristic searches with 1000 repli cates and tree- isection reconnection branch swapping holding 100 trees with multrees. Support was assessed via non-p using 1000 repli cates. A source of uncertainty for the introduced in this study is the plac ement of the Mucoromycotina and Glomeromycota. A multi-gene phylogeny of fungi indicates that the Mu deeper branch than the Glo ucoromycotina represents 23 While other an alyses support this placem 24 some alternatives also have support [25,26l. To address this analysed the dataset from ames er al. [23] by reducing the number of dikarya to 10 taxa each and increasing the Glomero- mycota to six and the M Euchytrides were ucoromycotina to nine taxa the outgroup. See the electronic supplementary material, table S3 for a list of taxa. Ni ucleotide datasets (18S rDNA, 26S rDNA, 5.8S rDNA) and protein datasets (TEE RPB, RPB2) were aligned with multiple sequence alignment based on fast Fourier transform I2 using the G NSi algorithm and ambiguous regions were excluded in GIranous PRO 128] resulting in a combined dataset with 5229 pos- itions. We applied an independent sui bstitution model to each region. The 18S and 26S rDNA were fitted with GTR. G models, 5.8 S rDNA with GTR+G, and proteins with JIT+G. estimated with maximum likelihood (ML and Bayes ian relaxed. clock (BRC). The MI was pet rformed with RAxML 129). Non-para metric bootstrap was calculated by rerunning 100 replicates for

Explanation / Answer

1.According to the article and figure 1, the group of fungi was found to have associations with basal groups of plants that lack roots is Glomeromycota, which consists the Arbescular Mycorrhizal Fungi. This fungi group was firstly discovered and most commonly found in association with the plant roots. Mycorrhizas are present in 92% of plant families studied with Arbuscular mycorrhizas being ancestral and predominant form, and the most prevalent symbiotic association found in the plant kingdom.

2. From conclusion, the two reasons that researchers believe Mucoromycotina is the earliest group of fungi to form associations with plants are as follows:-

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.