IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...
IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ... IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...
17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Session Details: Wednesday 30 November 2011 Plenary Session 5 0900 - 1030 Author: Janet Sprent University of Dundee, UK Presentation Title: Poles apart: Nodulation in native legumes from the Southern and Northern hemispheres Presentation Time: 0900 – 0930 Publications on legume biogeography generally ignore nodulation parameters and are usually discussed from a longitudinal perspective, with a bias towards the Old and New worlds (1). However, it has long been known that nodulation parameters can be useful taxonomic ones (2). Recent evidence on the evolution of nodulation (3), on the functions of different cells inside nodules (4) and on both the nature of nodulating bacteria (5) and whether or not they become terminally differentiated (6) suggests that there may be a latitudinal dimension to nodule evolution. This paper discusses nodulated legumes north and south of the equator pointing out both differences and similarities. Some of the former may be related to soil nutrient levels, which in much of the Northern hemisphere are relatively rich and much of the Southern hemisphere relatively poor, leading in the latter to many legumes evolving a broader suite of nutrient uptake systems (dual mycorrhizas, cluster roots) than those in the North (7). Further, nodulated caesalpinioid legumes and most of the nodulated mimosoids are usually in low latitudes on either side of the equator. On the other hand, certain groups of legumes in the North have extended into the Arctic Circle and these too may have particular characters. Bridging the N/S divide are many legume genera, for example Indigofera, which are adapted to dry environments (8). Major questions remain to be answered, including the reasons why nodulation evolved on several different occasions, why some legumes that lack uninfected cells in the infected region appear to function well, why (in the Southern hemisphere) legumes growing side-by-side have a preference for either alpha or beta proteobacteria and cases where current taxonomy does not align with nodule characters. References numbered (1) to (8) will be given in full in the talk and made available to anyone interested. 64 2011
17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Session Details: Wednesday 30 November 2011 Plenary Session 5 0900 - 1030 Authors: Erik Limpens 1 , Sergey Ivanov 1 , Evgenia Ovchinnikova 1,2 , Alexey Borisov 2 , Rik op den Camp 1 , Stephane de Mita 3 , René Geurts 1 , Elena Fedorova 1,4 , Ton Bisseling 1 1 Laboratory of Molecular Biology, Wageningen University, The Netherlands. 2 All-Russia Research Institute for Agricultural Microbiology, Laboratory of Genetics of Plant-Microbe Interactions, St. Petersburg, Russia. 3 Plant Diversity and Adaptation, Institute for Research and Development, Montpellier, France. 4 Timiryazev Institute of Plant Physiology RAS, Moscow, Russia. Presentation Title: Formation of a symbiotic interface in rhizobial and mycorrhizal symbioses Presentation Time: 0930 – 1000 In both the rhizobium-legume symbiosis and the arbuscular mycorrhizal symbiosis the microbes are hosted intracellularly in a novel, specialized membrane compartment that forms a symbiotic interface. The formation of this interface is at the heart of symbiosis. In the case of rhizobia they are accommodated as novel nitrogen-fixing organelles, called symbiosomes, inside infected cells of the root nodule. Arbuscular mycorrhizal (AM) fungi form highly branched hyphal structures, called arbuscules, in infected root cortical cells. In both cases the microbial symbiont is surrounded by a plant derived membrane that has a special plasma membrane identity and where generally a structured plant cell wall is lacking. It has recently become clear that the signaling molecules and signaling pathway that trigger these different symbioses are strikingly similar. We show that this signaling pathway also controls the formation of the symbiotic interfaces in both symbioses. The observed plasma membrane identity of both interface membranes indicates a major role for exocytotic vesicle traffic. By studying plasma membrane (PM) SNARE proteins we show that knock-down of specific PM SNARE members blocks the release of the bacteria from cell wall bound infection threads and/or subsequent symbiosome development. Furthermore, two specific SNARE proteins required for symbiosome formation are also essential for arbuscule formation by AM fungi. These results suggest that in evolution the ability to produce Nod factors gave rhizobia the ability to use the ancient AM machinery to recruit a specific exocytotic pathway for the establishment of a symbiotic interface. 65 2011
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17 th <strong>International</strong> Congress on <strong>Nitrogen</strong> <strong>Fixation</strong><br />
Fremantle, Western Australia<br />
27 November – 1 December 2011<br />
Session Details: Wednesday 30 November 2011<br />
Plenary Session 5<br />
0900 - 1030<br />
Author: Janet Sprent<br />
University of Dundee, UK<br />
Presentation Title: Poles apart: Nodulation in native legumes from the Southern and Northern hemispheres<br />
Presentation Time: 0900 – 0930<br />
Publications on legume biogeography generally ignore nodulation parameters and are usually discussed from a<br />
longitudinal perspective, with a bias towards the Old and New worlds (1). However, it has long been known that<br />
nodulation parameters can be useful taxonomic ones (2). Recent evidence on the evolution of nodulation (3), on<br />
the functions of different cells inside nodules (4) and on both the nature of nodulating bacteria (5) and whether or<br />
not they become terminally differentiated (6) suggests that there may be a latitudinal dimension to nodule<br />
evolution. This paper discusses nodulated legumes north and south of the equator pointing out both differences<br />
and similarities. Some of the former may be related to soil nutrient levels, which in much of the Northern<br />
hemisphere are relatively rich and much of the Southern hemisphere relatively poor, leading in the latter to many<br />
legumes evolving a broader suite of nutrient uptake systems (dual mycorrhizas, cluster roots) than those in the<br />
North (7). Further, nodulated caesalpinioid legumes and most of the nodulated mimosoids are usually in low<br />
latitudes on either side of the equator. On the other hand, certain groups of legumes in the North have extended<br />
into the Arctic Circle and these too may have particular characters. Bridging the N/S divide are many legume<br />
genera, for example Indigofera, which are adapted to dry environments (8). Major questions remain to be<br />
answered, including the reasons why nodulation evolved on several different occasions, why some legumes that<br />
lack uninfected cells in the infected region appear to function well, why (in the Southern hemisphere) legumes<br />
growing side-by-side have a preference for either alpha or beta proteobacteria and cases where current<br />
taxonomy does not align with nodule characters.<br />
References numbered (1) to (8) will be given in full in the talk and made available to anyone interested.<br />
64<br />
2011
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