Progress 10/01/19 to 09/30/20
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?We discussed our data in Sandhills research field site on the field tour day. There were around 20 graduate students from across the US studying different disciplines on soybean such as breeding, drought tolerant, cyst, and nutrition. Additionally, our PhD student presented a poster at the North Carolina Soil Science Society Annual Meeting, upwards of one hundred attendees were able to engage with this work throughout the meeting. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impact of the project: Agriculture in the 21st century faces multiple challenges: (1) the world population is expected to grow by 2.3 billion people by2050, and this growing population will need to be fed with smaller arable land resources, (2) the agricultural productivity of developing countries is still low compared to industrial nations, and (3) crop production needs to become more sustainable and adapt to climate change. Legume and cereal crops have been essential for the development of modern agricultural systems. However, since the Green Revolution, yield gains of cereal and legume crops have not kept pace with the required yield gains necessary to feed the growing world population. Cereal and legume crops are highly dependent on K fertilizers, particularly due to the increase of agriculturally used soils that are K-deficient. Given an increasing demand for higher crop yields, the development of a "Greener Revolution" in which alternative strategies are applied to enhance yields while the use of chemical fertilizers is reduced, should represent an urgent research priority and has the potential to improve the environmental sustainability of important agricultural systems. The findings of this project will be an important step towards the reduction of food and fuel production costs and will help agriculture thrive in a more environmentally sustainable manner by reducing the long-term dependence on energy-expensive and environmentally harmful chemical fertilizers. Unraveling these mechanisms on model and crop species will help scientists to breed and select varieties that are able to interact more efficiently with mycorrhizal fungi, and will help growers to make more informed decisions about the application of commercial fungal inocula on their farms, reduce fertilizer inputs, and increase the profitability. Objective 1: To demonstrate the direct transport of potassium from the soil to M. truncatula and maize plants via arbuscular mycorrhizal fungi. Rubidium (Rb) can serve as an analogous tracer for K and is taken up along the same pathways as K. Typically, rubidium levels are very low in soil and plant tissues. Rb has been used in other mycorrhizal symbioses to demonstrate the transport of K from the soil to colonized trees. However, only a very few studies have used this method to assess the K nutrition in the AM symbiosis. To fill this gap, we followed Rb transport from the fungus to the host in growth chamber systems with two separate compartments, a mycorrhizal root compartment (RC) and a fungal compartment (FC). Both compartments were separated by a double layer of a 50 μm nylon mesh with an air gap in between to prevent ion diffusion between the compartments and across-over of roots from the RC to the FC, but allowed hyphae to grow into the fungal compartment. M. truncatula seedlings were placed in one compartment filled with vermiculite and were inoculated with 200 spores of R. irregularis. During the following six weeks, the plants were watered with the same high or low K solutions that were used in our preliminary experiments. After six weeks of co-culture, stable Rb in the form of Rb nitrate (RbNO3) was added to the fungal compartment. Non-colonized plants served as control to verify that Rb did not leak into the mycorrhizal root compartment. Plant shoot tissues were homogenized, and Rb concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS) at the Environmental and Agricultural Testing Service laboratory at North Carolina State University (NCSU,https://eats.wordpress.ncsu.edu). Our results revealed that AM plants had significantly higher levels of Rb in their tissues than non-mycorrhizal plants, indicating that Rb was directly transported by the fungus to the host. In addition, Rb concentrations were significantly higher in AM plants cultivated at low K than those growing at high K. This indicates that (1) the fungal allocation of Rb was enhanced when the K demand of the plants was high, and (2) Rb can be used to track the transport of K. Objective 2: To test the effect of environmental factors on mycorrhiza-dependent potassium transport. Our objective here was to explore the role of AM fungi in plant K uptake of legumes grown in saline environments. M.truncatula was inoculated with AM fungal species Rhizophagus irregularis isolate 09, or remained uninoculated. Inoculated and non-inoculated plants were treated with nutrient solutions containing increasing concentrations of sodium (0, 50, 100, and200 mM). In order to observe the influence of AM fungi in plant K uptake, Rb was used as an analog tracer, and added to a separated soil compartment only accessible to the fungal hyphae. We hypothesize that the plants colonized with AM fungi will exhibit 1) higher tolerance to elevated levels of salinity and consequently better plant fitness compared to non-mycorrhizal control plants, and 2) higher transfers of Rb from the fungus to the plant in the presence of elevated concentrations of sodium. Plants grown without AM fungi remained severely stunted through the duration of the experiment. Older leaves of non-mycorrhizal (NM) plants were shed at nearly equal rate to the development of new leaves, probably the result of intensive K+deprivation, resulting in similar leaf counts for NM plants at both counting times. All NM plants exhibited a slightly yellow leaf coloration in comparison with mycorrhizal (AM) plant leaves, and NM petioles were generally shorter and more brittle. In addition, it was observed that very little branching or node development occurred for the NM plants in any treatment. Objective 3: To identify the plant genes that control the potassium uptake in mycorrhizal and non-mycorrhizal M. truncatula and maize plants. To further explore how the AM symbiosis improves the K nutrition of M. truncatula at low K, a transcriptome analysis using Illumina Hiseq2000 technology was performed on plant roots that were grown at high or low K and with or without mycorrhizal colonization by R. irregularis (Garcia et al., 2017). A total of twelve plants were selected per condition: three biological replicates containing each a pool of roots from four plants. After defining non-mycorrhizal plants growing at high K (NM+K) as the control condition, we were able to categorize genes from the other conditions (mycorrhizal plants at high K: AM+K; mycorrhizal plants at low K: AM-K; non-mycorrhizal plants at low K: NM-K) as significantly up-, down- or not regulated, and performed co-expression network analyses. This network analysis allowed us to identify regulatory connections between differentially expressed genes but also to predict which specific regulators (signaling proteins and transcription factors) may control the expression of genes of interest. This approach allowed us to identify 5, 7 and 7 putative key regulators of targets that were specifically up-regulated in AM-K, NM-K, or in low K independent on the mycorrhizal status (-K), respectively. Our data indicate that a significant fraction of the plant root transcriptional response to mycorrhizal symbiosis is dependent on the external K availability. We also described for the first time, the molecular adaptations of a legume to K deprivation. Altogether, our results indicate that the AM symbiosis helps plants to tolerate the negative impacts of long-term K deficiency by modulating the K-dependent transcriptional responses from the plant. The identification of putative key regulators in M.truncatula plants under K deficiency is very exciting and raises the question which role these regulators play in plant K nutrition.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Schenck C.A., Westphal J., Jayaraman D., Garcia K., Wen J., Mysore K.S., An� J.M., Sumner L.W., Maeda H.A. (2020) Role of cytosolic, tyrosine-insensitive prephenate dehydrogenase in Medicago truncatula. Plant Direct. 4: 1-15.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Garcia K., B�cking H., Zimmermann S.D. (2020) Editorial: Importance of root symbiomes for plant nutrition: New insights, perspectives, and future challenges. Frontiers in Plant Science. 11: 594.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Rush T.A., Puech-Pag�s V., Bascaules A., Jargeat P., Maillet F., Haouy A., Ma�s A.Q., Carrera Carriel C., Khokhani D., Keller-Pearson M., Tannous J., Cope K.R., Garcia K., Maeda J., Johnson C., Kleven B., Choudhury Q.J., Labb� J., Swift C., OMalley M.A., Bok J.W., Cottaz S., Fort S., Poinsot V., Sussman M.R., Lefort C., Nett J., Keller N.P., B�card G., An� J.M. (2020) Lipo-chitooligosaccharides as regulatory signals of fungal growth and development. Nature Communications. 11: 3897.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Garcia K., Guerrero-Gal�n C., Frank H.E.R., Haider M.Z., Delteil A., Con�j�ro G., Lambilliotte R., Fizames C., Sentenac H., Zimmermann S.D. (2020) Fungal Shaker-like channels beyond cellular K+ homeostasis: a role in ectomycorrhizal symbiosis between Hebeloma cylindrosporum and Pinus pinaster. PLOS ONE. 15(11): e0242739.
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Progress 10/01/18 to 09/30/19
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?As a part of outreach, the results were presented (posted) in the Department of Crop and Soil Sciences and at the 18th NC State University Annual Summer Undergraduate Research and Creativity Symposium by a REU undergraduate student from our Basic and Environmental Soil Science Training (BESST) program (https://reuncsu.wordpress.ncsu.edu/). There were more than 30 researchers including undergraduate, graduate, postdoc, and faculties in the Departmental presentation, and hundreds of attendees at the Symposium. We also discussed our data in Sandhills research field site on the field tour day. There were around 20 graduate students from across the US studying different disciplines on soybean such as breeding, drought tolerant, cyst, and nutrition. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impact of the project: Agriculture in the 21st century faces multiple challenges: (1) the world population is expected to grow by 2.3 billion people by 2050, and this growing population will need to be fed with smaller arable land resources, (2) the agricultural productivity of developing countries is still low compared to industrial nations, and (3) crop production needs to become more sustainable and adapt to climate change. Legume and cereal crops have been essential for the development of modern agricultural systems. However, since the Green Revolution, yield gains of cereal and legume crops have not kept pace with the required yield gains necessary to feed the growing world population. Cereal and legume crops are highly dependent on K fertilizers, particularly due to the increase of agriculturally used soils that are K-deficient. Given an increasing demand for higher crop yields, the development of a "Greener Revolution" in which alternative strategies are applied to enhance yields while the use of chemical fertilizers is reduced, should represent an urgent research priority and has the potential to improve the environmental sustainability of important agricultural systems. The findings of this project will be an important step towards the reduction of food and fuel production costs and will help agriculture thrive in a more environmentally sustainable manner by reducing the long-term dependence on energy-expensive and environmentally harmful chemical fertilizers. Unraveling these mechanisms on model and crop species will help scientists to breed and select varieties that are able to interact more efficiently with mycorrhizal fungi, and will help growers to make more informed decisions about the application of commercial fungal inocula on their farms, reduce fertilizer inputs, and increase the profitability. Objective 1: To demonstrate the direct transport of potassium from the soil to M. truncatula and maize plants via arbuscular mycorrhizal fungi. Rubidium (Rb) can serve as an analogous tracer for K and is taken up along the same pathways as K. Typically, rubidium levels are very low in soil and plant tissues. Rb has been used in other mycorrhizal symbioses to demonstrate the transport of K from the soil to colonized trees. However, only a very few studies have used this method to assess the K nutrition in the AM symbiosis. To fill this gap, we followed Rb transport from the fungus to the host in growth chamber systems with two separate compartments, a mycorrhizal root compartment (RC) and a fungal compartment (FC). Both compartments were separated by a double layer of a 50 µm nylon mesh with an air gap in between to prevent ion diffusion between the compartments and a cross-over of roots from the RC to the FC, but allowed hyphae to grow into the fungal compartment. M. truncatula seedlings were placed in one compartment filled with vermiculite and were inoculated with 200 spores of R. irregularis. During the following six weeks, the plants were watered with the same high or low K solutions that were used in our preliminary experiments. After six weeks of co-culture, stable Rb in the form of Rb nitrate (RbNO3) was added to the fungal compartment. Non-colonized plants served as control to verify that Rb did not leak into the mycorrhizal root compartment. Plant shoot tissues were homogenized, and Rb concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS) at the Environmental and Agricultural Testing Service laboratory at North Carolina State University (NCSU, https://eats.wordpress.ncsu.edu). Our results revealed that AM plants had significantly higher levels of Rb in their tissues than non-mycorrhizal plants, indicating that Rb was directly transported by the fungus to the host. In addition, Rb concentrations were significantly higher in AM plants cultivated at low K than those growing at high K. This indicates that (1) the fungal allocation of Rb was enhanced when the K demand of the plants was high, and (2) Rb can be used to track the transport of K. Objective 2: To test the effect of environmental factors on mycorrhiza-dependent potassium transport. Our objective here was to explore the role of AM fungi in plant K uptake of legumes grown in saline environments. M. truncatula was inoculated with AM fungal species Rhizophagus irregularis isolate 09, or remained uninoculated. Inoculated and non-inoculated plants were treated with nutrient solutions containing increasing concentrations of sodium (0, 50, 100, and 200 mM). In order to observe the influence of AM fungi in plant K uptake, Rb was used as an analog tracer, and added to a separated soil compartment only accessible to the fungal hyphae. We hypothesize that the plants colonized with AM fungi will exhibit 1) higher tolerance to elevated levels of salinity and consequently better plant fitness compared to non-mycorrhizal control plants, and 2) higher transfers of Rb from the fungus to the plant in the presence of elevated concentrations of sodium. Plants grown without AM fungi remained severely stunted through the duration of the experiment. Older leaves of non-mycorrhizal (NM) plants were shed at nearly equal rate to the development of new leaves, probably the result of intensive K+ deprivation, resulting in similar leaf counts for NM plants at both counting times (Fig. 1 & 2). All NM plants exhibited a slightly yellow leaf coloration in comparison with mycorrhizal (AM) plant leaves, and NM petioles were generally shorter and more brittle. In addition, it was observed that very little branching or node development occurred for the NM plants in any treatment. Objective 3: To identify the plant genes that control the potassium uptake in mycorrhizal and non-mycorrhizal M. truncatula and maize plants. To further explore how the AM symbiosis improves the K nutrition of M. truncatula at low K, a transcriptome analysis using Illumina Hiseq2000 technology was performed on plant roots that were grown at high or low K and with or without mycorrhizal colonization by R. irregularis (Garcia et al., 2017). A total of twelve plants were selected per condition: three biological replicates containing each a pool of roots from four plants. After defining non-mycorrhizal plants growing at high K (NM+K) as the control condition, we were able to categorize genes from the other conditions (mycorrhizal plants at high K: AM+K; mycorrhizal plants at low K: AM-K; non-mycorrhizal plants at low K: NM-K) as significantly up-, down- or not regulated, and performed co-expression network analyses. This network analysis allowed us to identify regulatory connections between differentially expressed genes but also to predict which specific regulators (signaling proteins and transcription factors) may control the expression of genes of interest. This approach allowed us to identify 5, 7 and 7 putative key regulators of targets that were specifically up-regulated in AM-K, NM-K, or in low K independent on the mycorrhizal status (-K), respectively. Our data indicate that a significant fraction of the plant root transcriptional response to mycorrhizal symbiosis is dependent on the external K availability. We also described for the first time, the molecular adaptations of a legume to K deprivation. Altogether, our results indicate that the AM symbiosis helps plants to tolerate the negative impacts of long-term K deficiency by modulating the K-dependent transcriptional responses from the plant. The identification of putative key regulators in M. truncatula plants under K deficiency is very exciting and raises the question which role these regulators play in plant K nutrition.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Guerrero-Gal�n C., Delteil A., Garcia K., Houdinet G., Sentenac H., Zimmermann S.D. (2018) Plant potassium nutrition in ectomycorrhizal symbiosis: properties and roles of the three fungal TOK potassium channels in Hebeloma cylindrosporum. Environmental Microbiology. 20: 1873-1887.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Guerrero-Gal�n C., Garcia K., Houdinet G., Zimmermann S.D. (2018) HcTOK1 participates in the maintenance of K+ homeostasis in the ectomycorrhizal fungus Hebeloma cylindrosporum, which is essential for the symbiotic K+ nutrition of Pinus pinaster. Plant Signaling & Behavior. 13(6): e1480845.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Becquer A.*, Garcia K.*, Amenc L., Rivard C., Dor� J., Trives-Segura C., Szponarski W., Russet S., Baeza Y., Lassalle B., Gay G., Zimmermann S.D., Plassard C. (2018) The Hebeloma cylindrosporum HcPT2 Pi transporter plays a key role in the ectomycorrhizal symbiosis. New Phytologist. 220(4): 1185-1199.
- Type:
Book Chapters
Status:
Published
Year Published:
2018
Citation:
Kafle A., Garcia K., Peta V., Yakha J., Soupir A., B�cking H. (2018) Beneficial plant microbe interactions and their effect on nutrient uptake, yield and stress resistance of soybeans. In Soybean - The Basis of Yield, Biomass and Productivity . Minobu Kasai (ed). IntechOpen. doi: 10.5772/intechopen.81396.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Becquer A., Garcia K., Plassard C. (2018) HcPT1.2 participates in Pi acquisition in Hebeloma cylindrosporum external hyphae of ectomycorrhizas under high and low phosphate conditions. Plant Signaling & Behavior. 13(10): e1525997.
- Type:
Book Chapters
Status:
Published
Year Published:
2018
Citation:
Guerrero-Gal�n C., Houdinet G., Calvo-Polanco M., Bonaldi K.E., Garcia K., Zimmermann S.D. (2018) The role of plant transporters in mycorrhizal symbioses. In "Membrane transport in plants". Christophe Maurel (ed). Advances in Botanical Research, Volume 87: 303-342.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Kafle A., Garcia K., Wang X., Pfeffer P.E., Strahan G.D., B�cking H. (2019) Nutrient demand and fungal access to resources control the carbon allocation to the symbiotic partners in tripartite interactions of Medicago truncatula. Plant, Cell & Environment. 42(1): 270-284.
- Type:
Book Chapters
Status:
Published
Year Published:
2019
Citation:
Becquer A., Guerrero-Gal�n C., Eibensteiner J.L., Houdinet G., Bu?cking H., Zimmermann S.D., Garcia K. (2019) The ectomycorrhizal contribution to tree nutrition. In "Molecular physiology and biotechnology of trees". Francisco C�novas (ed). Advances in Botanical Research, Volume 89.
- Type:
Book Chapters
Status:
Published
Year Published:
2019
Citation:
Kafle A., Cope K.R., Raths R., Krishna Yakha J., Subramanian S., B�cking H., Garcia K. (2019) Harnessing soil microbes to improve plant phosphate efficiency in cropping systems. Agronomy. 9(3): 127
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Plassard C., Becquer A., Garcia K. (2019) Phosphorus transport in mycorrhiza: how far are we? Trends in Plant Science. doi.org/10.1016/j.tplants.2019.06.004.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Cope K.R., Bascaules A., Irving T.B., Venkateshwaran M., Maeda J., Garcia K., Rush T., Ma C., Labb� J., Jawdy S., Steigerwald E., Setzke J., Fung E., Schnell K., Wang Y., Schlief N., B�cking H., Strauss S.H., Jargeat P., B�card G., Puech-Pag�s V., An� J.M. (2019) The ectomycorrhizal fungus Laccaria bicolor produces lipochitooligosaccharides and uses the common symbiosis pathway to colonize Populus. The Plant Cell. 31(10): 2386-2410
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Ruytinx J., Kafle A., Usmam M., Coninx L., Zimmermann S.D., Garcia K. (2019) Micronutrient transport in mycorrhizal symbiosis; zinc steals the show. Fungal Biology Reviews.
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