| 1. |
- Felten, Judith, et al.
(författare)
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The ectomycorrhizal fungus laccaria bicolor stimulates lateral root formation in poplar and arabidopsis through auxin transport and signaling
- 2009
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Ingår i: Plant Physiology. - Rockville : American society of plant biologists. - 0032-0889 .- 1532-2548. ; 151:4, s. 1991-2005
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Tidskriftsartikel (refereegranskat)abstract
- The early phase of the interaction between tree roots and ectomycorrhizal fungi, prior to symbiosis establishment, is accompanied by a stimulation of lateral root (LR) development. We aimed to identify gene networks that regulate LR development during the early signal exchanges between poplar (Populus tremula x Populus alba) and the ectomycorrhizal fungus Laccaria bicolor with a focus on auxin transport and signaling pathways. Our data demonstrated that increased LR development in poplar and Arabidopsis (Arabidopsis thaliana) interacting with L. bicolor is not dependent on the ability of the plant to form ectomycorrhizae. LR stimulation paralleled an increase in auxin accumulation at root apices. Blocking plant polar auxin transport with 1-naphthylphthalamic acid inhibited LR development and auxin accumulation. An oligoarray-based transcript profile of poplar roots exposed to molecules released by L. bicolor revealed the differential expression of 2,945 genes, including several components of polar auxin transport (PtaPIN and PtaAUX genes), auxin conjugation (PtaGH3 genes), and auxin signaling (PtaIAA genes). Transcripts of PtaPIN9, the homolog of Arabidopsis AtPIN2, and several PtaIAAs accumulated specifically during the early interaction phase. Expression of these rapidly induced genes was repressed by 1-naphthylphthalamic acid. Accordingly, LR stimulation upon contact with L. bicolor in Arabidopsis transgenic plants defective in homologs of these genes was decreased or absent. Furthermore, in Arabidopsis pin2, the root apical auxin increase during contact with the fungus was modified. We propose a model in which fungus-induced auxin accumulation at the root apex stimulates LR formation through a mechanism involving PtaPIN9-dependent auxin redistribution together with PtaIAA-based auxin signaling.
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| 2. |
- Kohler, Annegret, et al.
(författare)
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Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists.
- 2015
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 47:4, s. 176-410
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Tidskriftsartikel (refereegranskat)abstract
- To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergent evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.
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| 3. |
- Martin, Francis, et al.
(författare)
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The genome of Laccaria bicolor provides insights into mycorrhizal symbiosis
- 2008
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 452:7183, s. 7-88
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Tidskriftsartikel (refereegranskat)abstract
- Mycorrhizal symbioses -- the union of roots and soil fungi -- are universal in terrestrial ecosystems and may have been fundamental to land colonization by plants1,2. Boreal, temperate, and montane forests all depend upon ectomycorrhizae1. Identification of the primary factors that regulate symbiotic development and metabolic activity will therefore open the door to understanding the role of 2 ectomycorrhizae in plant development and physiology, allowing the full ecological significance of this symbiosis to be explored. Here, we report the genome sequence of the ectomycorrhizal basidiomycete Laccaria bicolor (Fig. 1) and highlight gene sets involved in rhizosphere colonization and symbiosis. This 65-million-base genome assembly contains ~ 20,000 predicted protein-encoding genes and a very large number of transposons and repeated sequences. We detected unexpected genomic features most notably a battery of effector-type small secreted proteins (SSP) with unknown function, several of which are only expressed in symbiotic tissues. The most highly expressed SSP accumulates in the proliferating hyphae colonizing the host root. The ectomycorrhizae-specific proteins likely play a decisive role in the establishment of the symbiosis. The unexpected observation that the genome of L. bicolor lacks carbohydrate-active enzymes involved in degradation of plant cell walls, but maintains the ability to degrade non-plant cell walls, reveals the dual saprotrophic and biotrophic lifestyle of the mycorrhizal fungus which enables it to grow within both soil and living plant roots. The predicted gene inventory of the L. bicolor genome, therefore, points to previously unknown mechanisms of symbiosis operating in biotrophic mycorrhizal fungi. The availability of this genome provides an unparalleled opportunity to develop a deeper understanding of the processes by which symbionts interact with plants within their ecosystem in order to perform vital functions in the carbon and nitrogen cycles that are fundamental to sustainable plant productivity.
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| 4. |
- Plomion, Christophe, et al.
(författare)
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Oak genome reveals facets of long lifespan
- 2018
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Ingår i: NATURE PLANTS. - : Springer Science and Business Media LLC. - 2055-026X .- 2055-0278. ; 4:7, s. 440-452
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Tidskriftsartikel (refereegranskat)abstract
- Oaks are an important part of our natural and cultural heritage. Not only are they ubiquitous in our most common landscapes' but they have also supplied human societies with invaluable services, including food and shelter, since prehistoric times(2). With 450 species spread throughout Asia, Europe and America(3), oaks constitute a critical global renewable resource. The longevity of oaks (several hundred years) probably underlies their emblematic cultural and historical importance. Such long-lived sessile organisms must persist in the face of a wide range of abiotic and biotic threats over their lifespans. We investigated the genomic features associated with such a long lifespan by sequencing, assembling and annotating the oak genome. We then used the growing number of whole-genome sequences for plants (including tree and herbaceous species) to investigate the parallel evolution of genomic characteristics potentially underpinning tree longevity. A further consequence of the long lifespan of trees is their accumulation of somatic mutations during mitotic divisions of stem cells present in the shoot apical meristems. Empirical(4) and modelling(5) approaches have shown that intra-organismal genetic heterogeneity can be selected for(6) and provides direct fitness benefits in the arms race with short-lived pests and pathogens through a patchwork of intra-organismal phenotypes(7). However, there is no clear proof that large-statured trees consist of a genetic mosaic of clonally distinct cell lineages within and between branches. Through this case study of oak, we demonstrate the accumulation and transmission of somatic mutations and the expansion of disease-resistance gene families in trees.
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| 5. |
- Rajashekar, Balaji, et al.
(författare)
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Expansion of signal pathways in the ectomycorrhizal fungus Laccaria bicolor- evolution of nucleotide sequences and expression patterns in families of protein kinases and RAS small GTPases.
- 2009
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 183:2, s. 365-379
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Tidskriftsartikel (refereegranskat)abstract
- * The ectomycorrhizal fungus Laccaria bicolor has the largest genome of all fungi yet sequenced. The large genome size is partly a result of an expansion of gene family sizes. Among the largest gene families are protein kinases and RAS small guanosine triphosphatases (GTPases), which are key components of signal transduction pathways. * Comparative genomics and phylogenetic analyses were used to examine the evolution of the two largest families of protein kinases and RAS small GTPases in L. bicolor. Expression levels in various tissues and growth conditions were inferred from microarray data. * The two families possessed a large number of young duplicates (paralogs) that had arisen in the Laccaria lineage following the separation from the saprophyte Coprinopsis cinerea. The protein kinase paralogs were dispersed in many small clades and the majority were pseudogenes. By contrast, the RAS paralogs were found in three large groups of RAS1-, RAS2- and RHO1-like GTPases with few pseudogenes. * Duplicates of protein kinases and RAS small GTPase have either retained, gained or lost motifs found in the coding regions of their ancestors. Frequent outcomes during evolution were the formation of pseudogenes (nonfunctionalization) or proteins with novel structures and expression patterns (neofunctionalization).
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| 6. |
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| 7. |
- Ranjan, Alok, et al.
(författare)
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Molecular basis of differential adventitious rooting competence in poplar genotypes
- 2022
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Ingår i: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 73:12, s. 4046-4064
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Tidskriftsartikel (refereegranskat)abstract
- Recalcitrant adventitious root (AR) development is a major hurdle in propagating commercially important woody plants. Although significant progress has been made to identify genes involved in subsequent steps of AR development, the molecular basis of differences in apparent recalcitrance to form AR between easy-to-root and difficult-to-root genotypes remains unknown. To address this, we generated cambium tissue-specific transcriptomic data from stem cuttings of hybrid aspen, T89 (difficult-to-root) and hybrid poplar OP42 (easy-to-root), and used transgenic approaches to verify the role of several transcription factors in the control of adventitious rooting. Increased peroxidase activity was positively correlated with better rooting. We found differentially expressed genes encoding reactive oxygen species scavenging proteins to be enriched in OP42 compared with T89. A greater number of differentially expressed transcription factors in cambium cells of OP42 compared with T89 was revealed by a more intense transcriptional reprograming in the former. PtMYC2, a potential negative regulator, was less expressed in OP42 compared with T89. Using transgenic approaches, we demonstrated that PttARF17.1 and PttMYC2.1 negatively regulate adventitious rooting. Our results provide insights into the molecular basis of genotypic differences in AR and implicate differential expression of the master regulator MYC2 as a critical player in this process.
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| 8. |
- Rigal, Adeline, et al.
(författare)
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The AINTEGUMENTA LIKE1 Homeotic Transcription Factor PtAIL1 controls the formation of Adventitious Root Primordia in Poplar
- 2012
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Ingår i: Plant Physiology. - : American Society of Plant Biologists. - 0032-0889 .- 1532-2548. ; 160:4, s. 1996-2006
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Tidskriftsartikel (refereegranskat)abstract
- Adventitious rooting is an essential but sometimes rate-limiting step in the clonal multiplication of elite tree germplasm, because the ability to form roots declines rapidly with age in mature adult plant tissues. In spite of the importance of adventitious rooting, the mechanism behind this developmental process remains poorly understood. We have described the transcriptional profiles that are associated with the developmental stages of adventitious root formation in the model tree poplar (Populus trichocarpa). Transcriptome analyses indicate a highly specific temporal induction of the AINTEGUMENTA LIKE1 (PtAIL1) transcription factor of the AP2 family during adventitious root formation. Transgenic poplar samples that overexpressed PtAIL1 were able to grow an increased number of adventitious roots, whereas RNA interference mediated the down-expression of PtAIL1 expression, which led to a delay in adventitious root formation. Microarray analysis showed that the expression of 15 genes, including the transcription factors AGAMOUS-Like6 and MYB36, was overexpressed in the stem tissues that generated root primordia in PtAIL1-overexpressing plants, whereas their expression was reduced in the RNA interference lines. These results demonstrate that PtAIL1 is a positive regulator of poplar rooting that acts early in the development of adventitious roots.
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