Source: UNIVERSITY OF CALIFORNIA, DAVIS submitted to
INFLUENCE OF NITROGEN FORM ON WHEAT CARBON FIXATION, GRAIN YIELD, AND PROTEIN YIELD
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
1011273
Grant No.
2017-67007-25930
Project No.
CA-D-PLS-2370-CG
Proposal No.
2016-06702
Multistate No.
(N/A)
Program Code
A1142
Project Start Date
Nov 1, 2016
Project End Date
Oct 31, 2021
Grant Year
2019
Project Director
Bloom, A. J.
Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Plant Sciences
Non Technical Summary
Overall goal: Rising atmospheric CO2 levels inhibit the conversion of nitrate into amino acids in wheat and compromise grain protein yields. Unfortunately, relatively little is known about wheat performance under ammonium nutrition. This research will determine the influence of CO2 concentration and nitrate and ammonium as nitrogen sources on wheat carbon fixation, grain yield, and protein yield, and the genetic bases of these responses.Supporting objectives: (a) To assess the balance between wheat nitrate and ammonium assimilation and its effects on carbon and protein deposition under elevated CO2. (b) To exploit the natural variation among wheat genotypes and new genetic tools for identifying loci and candidate genes associated with the differences in performance under ammonium nutrition and elevated CO2.Plans: A team of wheat physiologists and geneticists will (1) establish the range of ammonium tolerance among diverse wheat genotypes and conduct a GWAS to identify loci associated with this trait; (2) examine patterns of carbon fixation and deposition and nitrogen allocation under ambient and elevated CO2 in genotypes that show large differences in ammonium tolerance; (3) cross-validate major GWAS loci using QTL mapping in bi-parental segregating populations of recombinant inbred lines; (4) validate candidate genes using a sequenced population of TILLING mutants.Relevance: This research will improve the productivity and nutritional quality of wheat under the conditions anticipated in the near future. It addresses Program Area Priority Code A1141: "lead to a better understanding of how nitrogen supply brings about patterns of carbon fixation and deposition."
Animal Health Component
0%
Research Effort Categories
Basic
80%
Applied
20%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1021549101060%
1021549108040%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
1549 - Wheat, general/other;

Field Of Science
1010 - Nutrition and metabolism; 1080 - Genetics;
Goals / Objectives
The overall goal is to improve the productivity and nutritional quality of crops in the face of climate change. This research on wheat will determine the influence of inorganic nitrogen (N) form, nitrate (NO3-) vs. ammonium (NH4+), and atmospheric carbon dioxide (CO2) concentration on carbon fixation, grain yield, and protein yield, and the genetic bases of these responses. Thus, it will address Program Area Priority Code A1142: "include discoveries that lead to a better understanding of how nitrogen supply brings about patterns of carbon fixation and deposition."The short-term goals are to examine wheat responses to NH4+. Wheat breeding in United States has focused almost entirely on yield responses to NO3- nutrition because NO3- is the dominant N source in temperate agricultural soils. Relatively little is known about the yield responses of wheat receiving NH4+ nutrition. Rising atmospheric CO2 concentration inhibits the conversion of NO3- into protein in the shoots of wheat and other C3 plants and limits wheat protein yields. By contrast, such changes in CO2 have little effect on NH4+ conversion into protein. Therefore, managing N supply to balance soil NO3- and NH4+ availability and shifting wheat from NO3- to NH4+ as an N source will become a major bottleneck to grain production and quality. This project will examine diverse wheat lines receiving NO3- or NH4+ nutrition under ambient or elevated CO2 atmospheres to identify loci and candidate genes associated with higher grain yield and protein yield under the environmental conditions anticipated in the near future.
Project Methods
Establish the range of NH4+ tolerance for wheat genotypes in the National Small Grain Core Collection (NSGCC) and conduct a genome wide association study (GWAS) to identify loci associated with NH4+ tolerance under ambient and elevated CO2.Determine patterns of carbon fixation and deposition and nitrogen allocation under ambient and elevated CO2 in diverse genotypes, including those that show large differences in NH4+ tolerance. Characterize NO3- vs. NH4+ responsive physiological parameters in the genotypes that show large differences in the patterns of carbon fixation and deposition and nitrogen allocation. Cross-validate major GWAS loci using quantitative trait loci (QTL) mapping in bi-parental populations. Identify candidate genes and validate them using sequenced population of TILLING (Targeting Induced Local Lesions in Genomes) mutants in tetraploid wheat.

Progress 11/01/16 to 10/31/21

Outputs
Target Audience:This project targets a broad audience ranging from the general public which we reach through interviews published in newspapers (Cal Aggie and Davis Enterprise), on radio talk shows on KVDS (https://officehourucdpodcast.com/fall-2019/), and public webinars (e.g., New Brunswick Environmental Network, Master Gardeners of San Mateo County, UC Davis Alumni Association) to students through lectures to large general education classes and introductory classes to majors in biology and environmental sciences, and to other natural scientists through publications in refereed journals (including Nature Plants, Current Opinions, and Journal of Experimental Botany), and in presentations to annual meetings of scientific societies (e.g., New Zealand Plant Science Central meeting, Crop Society of America, AGU,NIFA-IWYP Project Director at Plant and Animal Genome Conference,Annual IWYP Science Program Conferences, and National Association of Plant Breeders) and symposia (e.g., Molecular Responses of Plants facing Climate Change and 50th anniversary of Bill Ogren's discovery of Rubisco oxygenase activity). Changes/Problems:COVID-19 caused a major disruption in the completion of this project. One of the undergraduates who worked on the project reported a sore throat, and so everyone on the project was banned from the university for two weeks despite the fact that everyone on the project had worked in well ventilated areas, separated by 3 meters, wore masks, disinfected all tools and surfaces before and after use, etc. This person had to wait one week to be tested and waited another 9 days to receive the results of the test, which proved to be negative. As a result, all of the plants in our current experiment died. We finally received permission to resume activities, but three to four months of work were wasted. To prevent similar problems, we divided the people on the project into two teams that had no direct contact with one another. Clearly this slowed our experimentation. We experienced difficulties with several of the sophisticated software for genetic analyses. farmCPU and TASSEL that we used to conduct GWAS and nested association mapping (NAM), respectively, had problems that were only solved with the release of new versions. We obtained excellent support from the Dubcovsky and Buckler labs and eventually were able to complete these analyses. What opportunities for training and professional development has the project provided?A graduate student Fulbright Scholar from Thailand worked on this project and made excellent progress. He directed teams of five UC Davis undergraduates to conduct the screens of ammonium tolerance in spring wheat. He also conducted the Genome Wide Association analyses in wheat and rice and Nested Association Mapping Analyses of the biparental segregating populations in wheat. A graduate student from New York State who had an undergraduate degree in engineering developed the ultra-high resolution oxygen analyzer. She grew up on a blueberry farm and is now evaluating ammonium tolerance in Arabidopsis. A postdoctoral scholar who has a Ph.D. in Chemistry from UC Davis has developed a new assay for evaluating the kinetics of carboxylation and oxygenation via Rubisco and examining the differences among Rubiscos purified from a wide variety of model species including tobacco, wheat, rice, spinach, and Arabidopsis. How have the results been disseminated to communities of interest?We made presentations at national and international meetings. We are scheduled to make additional presentations this year. We also have published in major journals. As the graduate student finish their theses and the postdoc prepare to leave for a faculty position, we anticipate at least eight more publications about this project will appear this year. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We have completed a very thorough Genome Wide Association Study (GWAS) of the growth of 875 genotypes of hexaploid wheat receiving 0.5 mM ammonium, 0.5 mM nitrate, or 10 mM ammonium as a sole nitrogen source. All genotypes were grown three times per year in two different years. Our results include: 1. The growth of most genotypes suffered under high ammonium, whereby the mean biomass under 10 mM ammonium was 80% of the biomass under 0.5 mM ammonium. 2. Most genotypes grew similarly under ammonium and nitrate, whereby the mean biomass under 0.5 mM ammonium did not differ from that under 0.5 mM nitrate. 3. The responses of the genotypes to the different N sources was not related to the origins of the genotypes. 4. Biomass responses to N sources had low heritability. 5. One dozen QTLs were significantly associated with responses to N sources in environments that vary in light levels and temperatures. To verify the QTLs that our GWAS identified, we grew eight biparental segregating populations with 75 lines per population that received 0.5 mM ammonium, 0.5 mM nitrate, or 10 mM ammonium as a sole N source. We have completed four replicate experiments in controlled environment chambers at ambient (430 ppm) and elevated atmospheric CO2 (750 ppm). Our results include: 1. The eight populations varied in their responses to N form. 2. Most genotypes grew slower under the 10 mM ammonium treatment at ambient or elevated CO2. 3. At ambient CO2, most genotypes accumulated more biomass under 0.5 mM nitrate than 0.5 mM ammonium because of more extensive root growth. 4. At elevated CO2, most genotypes accumulated more biomass under 0.5 mM ammonium than 0.5 mM nitrate because of more extensive shoot growth. 5. Larger the plants were at ambient CO2, the less responsive they were to elevated CO2 level, regardless of N form. We have now repeated the experiments on the two biparental segregating populations at ambient CO2 in a greenhouse. We have also conducted more detailed physiological experiments on the responses of thirteen genotypes that exhibited highly discrepant ammonium tolerance. This included evaluation of various photosynthetic and respiratory rates and nitrogen allocation patterns. We analyzed annual field trials of fall-planted common wheat in California from 1985 to 2019, a period during which global atmospheric CO2 concentration increased 19%. Even after accounting for other major factors (cultivar, location, degree-days, soil temperature, total water applied, nitrogen fertilization, and pathogen infestation), wheat grain yield and protein yield declined 13% over this period, but grain protein content did not change. These results suggest that expoure to gradual CO2 enrichment over the past 35 years has adversely affected wheat grain and protein yield, but not grain protein content.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Rubio-Asensio, J. S. and A. J. Bloom (2017) Inorganic nitrogen form: a major player in wheat and Arabidopsis responses to elevated CO2. Journal of Experimental Botany 68:2611-2625.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Kimball, B. A., P. J. Pinter Jr, R. L. LaMorte, S. W. Leavitt, D. J. Hunsaker, G. W. Wall, F. Wechsung, G. Wechsung, A. J. Bloom, and J. W. White (2017) Data from the Arizona FACE (Free-Air CO2 Enrichment) experiments on wheat at ample and limiting levels of water and nitrogen. Open Data Journal for Agricultural Research 3, DOI:10.18174/odjar.v3i1.15826
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Bloom, A. J. and P. Kameritsch (2017) Relative association of Rubisco with manganese and magnesium as a regulatory mechanism in plants. Physiologia Plantarum 161: 545-559, DOI:10.1111/ppl.12616.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Bloom, A. J. and K. M. Lancaster (2018) Manganese binding to Rubisco could drive a photorespiratory pathway that increases the energy efficiency of photosynthesis. Nature Plants 4:414-422, DOI:10.1038/s41477-018-0191-0.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Bloom, A. J. (2019) Metal regulation of metabolism, Current Opinion in Chemical Biology 49:33-38
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Bloom, A. J., P. Kasemsap, J. S. Rubio-Asensio (2020) Rising atmospheric CO2 concentration inhibits nitrate assimilation in shoots but enhances it in roots of C3 plants. Physiologia Plantarum 168 (4), 963-972
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Bloom, A. J. and R. E. Plant (2021) Wheat grain yield decreased over the past 35 years, but protein content did not change. Journal of Experimental Botany 72:6811-6821 DOI:10.1093/jxb/erab343.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Shi, X. and A. J. Bloom (2021) Photorespiration: The Futile Cycle? Plants 10:908.
  • Type: Journal Articles Status: Under Review Year Published: 2022 Citation: Shi, X. and A. J. Bloom (2022) Regulation of Rubisco kinetics by metal cofactors. Nature Plants, in review.
  • Type: Journal Articles Status: Submitted Year Published: 2022 Citation: Ghosh, S., S. Pulford, and A. J. Bloom (2022) Online science education meets face-to-face. Science, submitted.
  • Type: Books Status: Published Year Published: 2021 Citation: Bloom, A. J. (2022) Climate Change: Causes, Consequences, and Solutions, 3rd Edition. Smithsonian Institution, https://indd.adobe.com/view/7eafc24d-9151-4493-85d2-cb3f2e5a2a51, accessed January 22, 2022.
  • Type: Journal Articles Status: Under Review Year Published: 2022 Citation: Knapp, A. and A. J. Bloom (2022) Easy As piadcs: Libraries in Python and Go for ultra-high-resolution data acquisition using a Raspberry Pi. Applications in Plant Sciences, in review.
  • Type: Journal Articles Status: Under Review Year Published: 2022 Citation: Knapp, A., J. Stefani, E. Katz, and A. J. Bloom (2022) Quantifying leaf area of A. thaliana seedlings grown on agar plates using computer vision. Applications in Plant Sciences, in review.


Progress 11/01/19 to 10/31/20

Outputs
Target Audience:This project targets a broad audience ranging from the general public which we reach through interviews published innewspapers (Cal Aggie and Davis Enterprise), on radio talk shows on KVDS (https://officehourucdpodcast.com/fall-2019/), and public webinars (e.g., New Brunswick Environmental Network) to students through lectures to large general education classes and introductory classes to majors in biology andenvironmental sciences, and to other natural scientists through publications in refereed journals and in presentations to annual meetings of scientific societies (e.g., AGU and National Association of Plant Breeders) and symposia. Changes/Problems:COVID-19 has caused a major disruption in the completion of our project. One of the undergraduates who is working on the project reported a sore throat, and so everyone on the project was banned from the university for two weeks despite the fact that everyone on the project had worked in well ventilated areas, separated by 3 meters, wore masks, disinfected all tools and surfaces before and after use, etc. This person had to wait one week to be tested and waited another 9 days to receive the results of the test, which proved to be negative. As a result, all of the plants in our current experiment died. We have been given permission to resume activities, but three to four months of work was wasted. To prevent any future problems like this, we now have divided the people on the project into two teams that have no direct contact with one another. We also have experienced difficulties with the sophisticated software TASSEL (Trait Analysis by aSSociation, Evolution and Linkage) that we are using to conduct nested association mapping (NAM) using the data from the biparental segregating populations. A new version was just released on July 9, 2020 that should address these problems. We are obtaining excellent support from the Dubcovsky and Buckler labs and are optimistic that this approach will be successful. What opportunities for training and professional development has the project provided?A graduate student Fulbright Scholar from Thailand is working on this project and making excellent progress. He is directing directed a team of five UC Davis undergraduates to conduct the screens of ammonium tolerance in spring wheat. He is also conducting the Genome Wide Association analyses in wheat and rice and Nested Association Mapping Analyses of the bi-parental segregating populations in wheat. A graduate student from New York State who has an undergraduate degree in engineering is developing the ultra-highresolution oxygen analyzer. She grew up on a blueberry farm and is now evaluating ammonium tolerance in Arabidopsis. A postdoctoral scholar who has a Ph.D. in Chemistry from UC Davis has developed a new assay for evaluating the kinetics of carboxylation and oxygenation via Rubisco and examining the differences among Rubiscos purified from a wide variety of model species including tobacco, wheat, rice, spinach, and Arabidopsis. How have the results been disseminated to communities of interest?We have made presentations at national and international meetings. We also have published in major journals. What do you plan to do during the next reporting period to accomplish the goals?We are making good progress on all the remaining portions of the project and anticipate that: The greenhouse experiments on the eight biparental populations at ambient CO2 will be finished in October, 2020. The Nested Association Mapping analyses of the data for the eight biparental populations will be completed by November, 2020. The physiological characterizations of genotypes with differing ammonium tolerance will be completed by June, 2021. The theses and manuscripts will be submitted by October, 2021

Impacts
What was accomplished under these goals? We have completed a very thorough Genome Wide Association Study (GWAS) of the growth of 875 genotypes of hexaploid wheat receiving 0.5 mM ammonium, 0.5 mM nitrate, or 10 mM ammonium as a sole nitrogen source. All genotypes were grown three times per year in two different years. Our results include: The growth of most genotypes suffered under high ammonium, whereby the mean biomass under 10 mM ammonium was 80% of the biomass under 0.5 mM ammonium. Most genotypes grew similarly under ammonium and nitrate, whereby the mean biomass under 0.5 mM ammonium did not differ from that under 0.5 mM nitrate. The responses of the genotypes to the different N sources was not related to the origins of the genotypes. Biomass responses to N sources had low heritability. One dozen QTLs were significantly associated with responses to N sources in environments that vary in light levels and temperatures. To verify the QTLs that our GWAS identified, we grew eight biparental segregating populations with 75 lines per population that received 0.5 mM ammonium, 0.5 mM nitrate, or 10 mM ammonium as a sole N source. We have completed four replicate experiments in controlled environment chambers at elevated atmospheric CO2 (750 ppm). Our results include: The eight populations varied in their responses to N form. Most genotypes grew slower under the 10 mM ammonium treatment. Most genotypes accumulated more biomass under 0.5 mM nitrate than 0.5 mM ammonium because of more extensive root growth. We are now repeating the experiments on the eight biparental segregating populations at ambient CO2 in a greenhouse. We are also conducting more detailed physiological experiments on the responses of four genotypes that exhibit highly discrepant ammonium tolerance. This includes evaluation of various photosynthetic and respiratory rates and nitrogen allocation patterns. We analyzed annual field trials of fall-planted, common wheat in California from 1985 to 2019 in which 673 cultivars were grown in 12 counties. During this period, global CO2 concentrations increased nearly 20%. Grain yield and grain protein yield per hectare declined more than 0.2% per year while grain protein content did not change even after accounting for other major factors (cultivar, location, degree-days, soil temperature, total water applied, nitrogen fertilization, and pathogen infestation). These results suggest that wheat, when exposed to gradual CO2 enrichment, sacrificed grain yield and protein yield for stable grain protein content and that rising CO2 has already compromised food security.

Publications

  • Type: Journal Articles Status: Published Year Published: 2020 Citation: AJ Bloom, P Kasemsap, JS Rubio?Asensio, Rising atmospheric CO2 concentration inhibits nitrate assimilation in shoots but enhances it in roots of C3 plants. Physiologia Plantarum 168 (4), 963-972
  • Type: Journal Articles Status: Under Review Year Published: 2020 Citation: AJ Bloom & R Plant, Wheat grain yield decreased over the past 34 years, but protein content did not change. Nature Food
  • Type: Journal Articles Status: Submitted Year Published: 2020 Citation: S. Ghosh, S. Pulford, AJ Bloom. Online Course meets Face-to-Face. Am Ed Res J
  • Type: Books Status: Under Review Year Published: 2021 Citation: Climate Change: Causes, Consequences, and Solutions, 2nd Edition, Cambridge U. Press


Progress 11/01/18 to 10/31/19

Outputs
Target Audience:This project targets a broad audience ranging from the general public which we reach through interviews published in newspapers (Cal Aggie and Davis Enterprise) and on radio talk shows on KVDS (https://officehourucdpodcast.com/fall-2019/), to students through lectures to large general education classes and introductory classes to majors in biology and environmental sciences, and to other natural scientists through publications in refereed journals and in presentations to annual meetings of scientific societies (e.g., National Association of Plant Breeders) and symposia. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?A graduate student from Thailand with a Fulbright Scholarship is working on this project and making excellent progress. He is directing directed a team of five UC Davis undergraduates to conduct the screens of ammonium tolerance in spring wheat. A graduate student from New York State who has an undergraduate degree in engineering is developing the ultra-high resolution oxygen analyzer. She grew up on a blueberry farm and is now evaluating ammonium tolerance in Arabidopsis. A postdoctoral scholar who has a Ph.D. in Chemistry from UC Davis has developed a new assay for evaluating the kinetics of carboxylation and oxygenation via Rubisco and examining the differences among Rubiscos purified from a wide variety of crops including tobacco, wheat, rice, and tomato. How have the results been disseminated to communities of interest?We have made presentations at national and international meetings. We also have published in major journals. What do you plan to do during the next reporting period to accomplish the goals?We are currently conducting sophisticated analyses on the genetic and physiological bases of ammonium tolerance in wheat, rice, and Arabidopsis. We are continuing development of portable, ultra-high resolution oxygen analyzer for assessing wheat ammonium vs. nitrate assimilation in the field.

Impacts
What was accomplished under these goals? We have conducted an thorough screen of ammonium tolerance in 875 accessions of spring wheat under ambient CO2 atmospheres and analyzed the results with a Genome-Wide Association Study (GWAS). Growth of the accessions under high ammonium ranged from 50% to 130% of growth under low ammonium; growth of the accessions under low nitrate ranged from 50% to 150% of growth under low ammonium. This variances were consistent over five replications. Certain loci were significantly associated with these phenotypes. We have now completed evaluating 8 bi-parental populations of hexaploid wheat for which the parents differ significantly in their ammonium tolerance, and we have begun to analyze the results. We have examined protein yields of 10 cultivars of spring wheat grown at the same sites in California for nearly 30 years. Removing disease and rising temperatures as factors, protein yields have declined at the sites with high soil nitrification rates and have increased at the sites with low nitrification rates. This seems consistent with our hypothesis that rising atmospheric CO2 concentrations inhibit nitrate assimilation. We are continuing development of a portable, ultra-high resolution oxygen analyzer for assessing non-destructively wheat ammonium vs. nitrate assimilation in the field.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Metal regulation of metabolism, Current Opinion in Chemical Biology 49:33-38
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2019 Citation: Rising atmospheric CO2 concentration inhibits nitrate assimilation in shoots but enhances it in roots of C3 plants, Physiologia Plantarum https://doi.org/10.1111/ppl.13040
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Reducing the Carbon Footprint of Academic Travel, Inside Higher Ed, April 18, 2019.


Progress 11/01/17 to 10/31/18

Outputs
Target Audience:We have targeted researchers and breeders from academia, governments, NGOs, and industry who are working on wheat and other small grains. To reach this targeted audience, we made presentations at the Crop Society of America Annual Conference in Tampa, Florida October 22 - 26, 2017, the NIFA-IWYP Project Director meeting on January 14, 2018 at Plant and Animal Genome Conference in San Diego, the 3rd Annual IWYP Science Program Conference held at John Innes Centre / Earlham Institute on June 11 - 14, 2018. We also published new hypothesis about plant photosynthesis and respiration in Nature Plants. Changes/Problems:We have interviewed several candidates for the postdoc positions funded by this project, but have yet to find suitable persons. We are continuing the search. What opportunities for training and professional development has the project provided?A graduate student from Thailand with a Fulbright Scholarship is working on this project and making excellent progress. He is directing directed a team of five UC Davis undergraduates to conduct the screens of ammonium tolerance in spring wheat. How have the results been disseminated to communities of interest?We have made presentations at national and international meetings. We also have published in major journals. What do you plan to do during the next reporting period to accomplish the goals?We are currently conducting screens of ammonium tolerance in bi-parental hexaploid wheat populations under ambient and elevated CO2 atmospheres in controlled environmental chambers. We are continuing development of portable, ultra-high resolution oxygen analyzer for assessing wheat ammonium vs. nitrate assimilation in the field.

Impacts
What was accomplished under these goals? We have conducted an thorough screen of ammonium tolerance in 875 accessions of spring wheat under ambient CO2 atmospheres and analyzed the results with a Genome-Wide Association Study (GWAS). Growth of the accessions under high ammonium ranged from 50% to 130% of growth under low ammonium; growth of the accessions under low nitrate ranged from 50% to 150% of growth under low ammonium. This variances were consistent over five replications. Certain loci were significantly associated with these phenotypes. We are now evaluating 8 bi-parental populations of hexaploid wheat for which the parents differ significantly in their ammonium tolerance. Phenotyping of four populations is near completion, and we have begun to analyze the results. We have examined protein yields of 10 cultivars of spring wheat grown at the same sites in California for nearly 30 years. Removing disease and rising temperatures as factors, protein yields have declined at the sites with high soil nitrification rates and have increased at the sites with low nitrification rates. This seems consistent with our hypothesis that rising atmospheric CO2 concentrations inhibit nitrate assimilation. A few cultivars showed increasing protein yields over time, whereas a few others showed decreasing protein yields over time. We are now examining whether these differences derive from differences in ammonium tolerance. We are continuing development of a portable, ultra-high resolution oxygen analyzer for assessing non-destructively wheat ammonium vs. nitrate assimilation in the field.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Bloom, A. J. and K. M. Lancaster (2018) Manganese binding to Rubisco could drive a photorespiratory pathway that increases the energy efficiency of photosynthesis. Nature Plants 4:414-422, DOI:10.1038/s41477-018-0191-0.
  • Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Metal control of metabolism. Current Opinion in Chemical Biology, invited submission
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Bloom, A. J. and P. Kameritsch (2017) Relative association of Rubisco with manganese and magnesium as a regulatory mechanism in plants. Physiologia Plantarum 161: 545-559, DOI:10.1111/ppl.12616.


Progress 11/01/16 to 10/31/17

Outputs
Target Audience:We have targeted researchers and breeders from academia, governments, NGOs, and industry who are working on wheat and other small grains. To reach this targeted audience, we made presentations at NIFA-IWYP Project Director meeting on January 15, 2017 at Plant and Animal Genome Conference in San Diego, the Annual IWYP Science Program Conference held in Obregon, Mexico in conjunction with CIMMYT on March 19 - 24, 2017, and the Plant Science Central meeting in Palmerston North, New Zealand on July 4 - 6, 2017. We also published all the data from Wheat FACE project conducted in Maricopa, AZ and have published a review on wheat responses to elevated CO2. Changes/Problems:We have interviewed several candidates for the postdoc positions funded by this project, but have yet to find suitable persons. We are continuing the search. One candidate seems promising and will visit the laboratory in the near future. What opportunities for training and professional development has the project provided?Porpipat Kasemsap, a graduate student from Thailand with a Fullbright Scholarship, has directed a team of four UC Davis undergraduates to conduct the screens of ammonium tolerance in spring wheat. Shuping Xiong, a visiting professor from Nanjing Agricultural University, China, has been also participating for the last few months. How have the results been disseminated to communities of interest?We have made presentations at NIFA-IWYP Project Director meeting on January 15, 2017 at Plant and Animal Genome Conference in San Diego, the Annual IWYP Science Program Conference held in Obregon, Mexico in conjunction with CIMMYT on March 19 - 24, 2017, and the Plant Science Central meeting in Palmerston North, New Zealand on July 4 - 6, 2017. We also published all the data from Wheat FACE project conducted in Maricopa, AZ and have published a review on wheat responses to elevated CO2. What do you plan to do during the next reporting period to accomplish the goals?We are currently repeating the screens of ammonium tolerance in spring wheat under ambient and elevated CO2 atmospheres in greenhouses and controlled environmental chambers. We are continuing development of portable, ultra-high resolution oxygen analyzer for assessing wheat ammonium vs. nitrate assimilation in the field.

Impacts
What was accomplished under these goals? We have conducted an thorough screen of ammonium tolerance in 875 accessions of spring wheat under ambient CO2 atmospheres and analyzed the results with a Genome-Wide Association Study (GWAS). Growth of the accessions under high ammonium ranged from 50% to 130% of growth under low ammonium; growth of the accessions under low nitrate ranged from 50% to 150% of growth under low ammonium. This variances were consistent over five replications. Certain loci were significantly associated with these phenotypes. We are continuing development of a portable, ultra-high resolution oxygen analyzer for assessing non-destructively wheat ammonium vs. nitrate assimilation in the field.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Rubio-Asensio, J. S. and A. J. Bloom (2017) Inorganic nitrogen form: a major player in wheat and Arabidopsis responses to elevated CO2. Journal of Experimental Botany 68:2611-2625.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Kimball, B. A., P. J. Pinter Jr, R. L. LaMorte, S. W. Leavitt, D. J. Hunsaker, G. W. Wall, F. Wechsung, G. Wechsung, A. J. Bloom, and J. W. White (2017) Data from the Arizona FACE (Free-Air CO2 Enrichment) experiments on wheat at ample and limiting levels of water and nitrogen. Open Data Journal for Agricultural Research 3.
  • Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Bloom, A. J. and P. Kameritsch (2017) Relative association of Rubisco with manganese and magnesium as a regulatory mechanism in plants. Physiologia Plantarum in press.
  • Type: Books Status: Published Year Published: 2017 Citation: Bloom, A. J. (2017) Climate Change: Causes, Consequences, and Solutions, Smithsonian Institution, Encyclopedia of Earth. https://indd.adobe.com/view/8f2ed4a1-a1b0-4f12-b5bb-5009bbbad0f3.