Progress 01/01/16 to 12/31/20
Outputs
Target Audience:Target audiences included research scientists in plant physiology, plant breeding, genetics and genomics, and agronomy, and growers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One gradaute student gained experinece in field evaluation of heat stress response of the mapping populations, genotyping-by-sequencing of genetic mapping populations, andgenetic mapping of heat stress response. A second graduate student worked on this project gained experience in RNA extraction, literature review in RNA sequencing in crops, 3' RNA-sequencing, differential expression analysis,gene co-expression network anlaysis, and physiolgical measurement analysis, and lipidomics analysis. Several undergradaute students participated the field experiment to increase the seeds for mapping populations, greenhouse experirment for tisuss sampling of the mapping population for genotyping, and greenhouse experiments for leaf tissue sampling for genotyping-by-sequencing. How have the results been disseminated to communities of interest?We published the paper in Crop Science in 2018, representing a starting point to further elucidate the genetic control of heat stress response in North American maize germplasm. To our knowledge, this is the first peer-reviewed paper of a genetic mapping study in field-based heat-tress response using North American maize germplasm. Given the anticipated interest, we published the paper in Open Access. This paper was selected to be highlighted in a CSA News article by Crop Science Soceity of America. We presented initial findings at multiple scientific meetings and will submit the final manuscripts to peer-reviewed journals. 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: Although heat stress is regarded a major production challenge, limited research wasconducted in the past. From this project, we completed and publishedthe first geneticmapping study in field-based heat-tress response using North American maize germplasm. Quantitative trait loci were detected for leaf firing, leaf blotching, tassel blasting, andreduction in spikelet size. In addition, our research showed that examing the groups of maize accessions showing either resistant or susceptible heat stress responses for their gene expression patterns through time-series analysis is a powerful approach to identify clusters of genes withsignificantly altered expression levels. Unlike earlier studies with young seedling leaves and limited genotypes, this researchprovided a comprehensive characterization of gene expression changes in response to heat stress, which will be useful to help pinpoint genes within the quantitative trait locidetected in genetic mapping experiments. By working on both heat stress responses in controlled greenhouse conditions and conducting genetic mapping of heat tolerance responses under natural field conditions, this project addressedthe knowledge gap between genetic and physiological mechansims and field production challenges. Protocols developed in this project and findings from our analysis provided critical information to guide future research in screeing the maize germplasm, breeding heat tolerance maize inbreds and hybrids, and, more broaldy,designing marker-assisted selection, genomic selection, and genome editing approaches to develop climate resilient crops. Objective 1: Quantify the natural variation in heat stress response across a diverse set of maize inbred lines and identify underlying mechanisms through integrating analysis at the gene-expression, biochemical, and whole-plant level. We completed the comprehensivegenome-wide transcriptional profiling through 3' mRNA-sequencing acrossdiverse maize accessions. This involved 4 time points (before heat stress treatment, 2-hour, 4-hour, and 72-hour after the treatment), 4 differen leaves (mature leaf, 2nd developing leaf, 3rd developing leaf, and 4th developing leaf), and 27 maize accessions (3 additional key maize accessions were added to the original 24-accession list). Our analysisidentified differentially expressed genes (DEGs), ranging from 4,000 to 7,000,for two distinct heat response groups (tolerant and susceptible) at each time point. Gene ontology analyses uncovered shared and unique responding patterns for the two groups along the time series. Through motif enrichment analyses, 195 transcription factors were identified as potential regulators of heat response. Gene co-expression network analysis indicated that genes involved in heat stress response were clustered in several keymodules such asPhotosynthesis, DNA & protein biosynthesis, Response to heat, and Plant hormone signal transduction, and Jasmonic acid mediated signaling pathway. In addition, we completed the physiological characterization and lipidome analysis of 27 divese maize accessions. Objective 2: Identify the genetic loci that contribute to the differential heat stress response through meta-analysis of two populations. We completed genetic mapping of heat stress responses with two biparental recombinant inbred line (RIL) populations (B73 × NC350 and B73 × CML103) and published the findings. This publication representsa starting point toelucidate the genetic control of heat stress response in North American maize germplasm. We completed the development of three new genetic mapping populations (B76 x B106, B76 x NC350, and B106 x NC350). Field evaluation of thesegenteic mapping populations for heat stress response was conducted in 2018, 2019, and 2020in Lubbock, Texas. Genotyping-by-sequencing and genetic mapping anlaysis are being carried out.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Advancing Understanding of Maize Heat Stress Response Mechanisms by Integrated Molecular, Biochemical, and Whole-Plant Analysis. 7th Iowa State University R.F. Baker Plant Breeding Symposium, Ames, Iowa.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Advancing Understanding of Maize Heat Stress Response Mechanisms by Integrated Molecular, Biochemical, and Whole-Plant Analysis. 62nd Annual Maize Genetics Conference, Virtual.
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Progress 01/01/19 to 12/31/19
Outputs
Target Audience:Target audiences include research scientists in plant physiology, plant breeding, genetics and genomics, and agronomy, and growers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One gradaute studentgained experience in field evaluation of heat stress response of themapping populations. A second graduate studentgained experience in RNA extraction,3' RNA-sequencing experiment, and data anlaysis. Several undergradaute students participated the field experiment to increase the seeds for twomapping populations. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?We will continue to conduct field experiments with three mapping populations and will conduct genotyping-by-sequencing to obtain marker data. We will continue the data analysis from RNA-sequencing, physiological measurements,and lipid profiling.
Impacts
What was accomplished under these goals?
We completed RNA extraction for all samples and a pilot run of3' RNA-sequencing analysis. We completed the data analysis of the pilot run and were able to detect differentially expressed genes and construct gene co-expression networks. We conductedthe field experiments of three mapping populations (B76 x B106, B76 x NC350, andB106 x NC350) at Lubbock Texas. Phenotypic data were collected forplant height, ear height, tassel blasting, late-season leaf firing, and late-season leaf blotching.
Publications
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Progress 01/01/18 to 12/31/18
Outputs
Target Audience:Target audiences include research scientists in plant physiology, plant breeding, genetics and genomics, and agronomy, and growers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One gradaute student worked on this project traveled to Lubbock Texas and gained experinece in field evaluation of heat stress response of a mapping population. A second graduate student worked on this project gained experience in RNA extraction and reviewed the literature in RNA sequencing in crops. Several undergradaute students participated the field experiment to increase the seeds for two other mapping population and the greenhouse experirment for tisuss sampling of the mapping population for genotyping. How have the results been disseminated to communities of interest?We published the paper in Crop Science in 2018, representing a starting point to further elucidate the genetic control of heat stress responsein North American maize germplasm. To our knowledge, this is the first peer-reviewed paper of a genetic mapping study in field-based heat-tress responseusing North American maize germplasm. Given the anticipated interest, we published the paper in Open Access. This paper was selected to be highlighted in aCSA News article by Crop Science Soceity of America. What do you plan to do during the next reporting period to accomplish the goals?We will conduct field experiments with the threemapping populations, as well as the 28-line set. We will conduct RNA extraction and sequencing andcomplete data analysis for membrane thermostability measurements andlipid profiling.
Impacts
What was accomplished under these goals?
IMPACT: We worked on elucidating the genetic and physiological mechanisms of heat stress response in maize. The project addresses the knowledge gap between model species and crops on heat stress response. With the initial experiments, we have collected extensive physiological data in-greenhouse to differentiate maize inbreds and developed genetic populations for further field characterization of heat stress response and genetic mapping. Objective 1: Quantify the natural variation in heat stress response across a diverse set of maize inbred lines and identify underlying mechanisms through integrating analysis at the gene-expression, biochemical, and whole-plant level. We completed two sets ofexperiments: lipid profiling and membrane thermostability analysis, and made proress in the third expeirments.We worked on comparining diffiernet RNA extraction protocols and examined the sequencing reads and costs betweent the estbalished RNA-seq and the new 3' RNA-seq. Objective 2: Identify the genetic loci that contribute to the differential heat stress response through meta-analysis of two populations. We conducted the field experiments at Lubbock Texas withthe first mapping population, B76/B106, a doubled haploid (DH) population with 224 individuals. We completed the development (seed increase) of two other mapping population at Ames Iowa, B76/NC350with 123 recombinant inbred lines (RILs), andNC350/B106with 144 RILs.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
McNellie, J.P., J. Chen, X. Li, and J. Yu. 2018. Genetic mapping of foliar and tassel heat stress tolerance in maize. Crop Science 58:2484-2493.
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Progress 01/01/17 to 12/31/17
Outputs
Target Audience:Other scientists working on maize heat stress Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?On the physiology side, we have trained 3 undergraduate students for sample collection, lipid extraction, and membrane stability measurement. On the breeding sides, summer nursery to develop three mapping populations provided an opportunity to expose 3 undergraduate students to plant breeding and genetics research. How have the results been disseminated to communities of interest?One graduate student presented a poster at the 59th Annual Maize Genetics Conference. What do you plan to do during the next reporting period to accomplish the goals?We will conduct RNA extraction and sequencing, complete data analysis for membrane thermostability measurements, complete lipid profiling and data analysis, and conduct field experiments with the developed mapping populations.
Impacts
What was accomplished under these goals?
We worked on elucidating the genetic and physiological mechanisms of heat stress response in maize. The project addresses the knowledge gap between model species and crops on heat stress response. With the initial experiments, we have collected extensive physiological data in greenhouse to differentiate maize inbreds and developed genetic populations for further field characterization of heat stress response and genetic mapping. Objective 1: Quantify the natural variation in heat stress response across a diverse set of maize inbred lines and identify underlying mechanisms through integrating analysis at the gene-expression, biochemical, and whole-plant level. We conducted three experiments: tissue sampling for RNA sequencing, lipid profiling, and membrane thermostability analysis. These experiments were conducted in a coordinated fashion so that data generated from three experiments can be analyzed together. A set of 28 inbreds were assembled to include the core set of 24 inbreds lines and 4 additional inbreds (Mo17, B73, B104, and CML277). These inbreds were grown under optimal condition in a greenhouse with an appropriate experimental design. The plants were divided into two groups: one for heat treatment and one as control. Leaf punches were collected for RNA extraction and sequencing. A separate set of leaf punches were collected for lipid extraction and lipid profiling is ongoing. A third set of leaf punches were collected for electrolyte leakage analysis, and preliminary results were obtained. Objective 2: Identify the genetic loci that contribute to the differential heat stress response through meta-analysis of two populations. We completed the development of a set of connected mapping populations. The first one, B76/B106, is a doubled haploid (DH) population with 224 individuals. The second one, B76/NC350, is a population with 123 recombinant inbred lines (RILs), The third population, NC350/B106, with 144 RILs.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
McNellie, J.P., X. Li, J. Chen, J. Yu. 2017. Advancing understanding of heat stress response mechanisms by integrated, molecular, biochemical, and whole-plant analysis. The 59th Annual Maize Genetics Conference, p201.
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Progress 01/01/16 to 12/31/16
Outputs
Target Audience:We discussed the project and initial findings with other scientists working on maize heat stress. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?We have trained 3 undergraduate students for sample collection, lipid extraction, membrane stability measurement, and gas exchange and chlorophyll fluorescence measurement How have the results been disseminated to communities of interest?We discussed the project and initial findings with other scientists working on maize heat stress. What do you plan to do during the next reporting period to accomplish the goals?We will collect samples for lipidomics and RNA sequencing, perform membrane stability and chlorophyll content measurements, increase seeds of three mapping populations, and start analyzing the data collected.
Impacts
What was accomplished under these goals?
Our project goal is to elucidate the genetic and physiological mechanisms of heat stress response in maize. The project addresses the knowledge gap between model species and crops on heat stress response. With the initial experiments, we have collected extensive physiological data in greenhouse to differentiate maize inbreds and developed genetic populations for further field characterization of heat stress response and genetic mapping. Objective 1: Quantify the natural variation in heat stress response across a diverse set of maize inbred lines and identify underlying mechanisms through integrating analysis at the gene-expression, biochemical, and whole-plant level. We conducted 3 greenhouse experiments and performed two types of heat stress measurements for the 27 inbreds under controlled environments. The original inbred list was expanded to include B73, Mo17 and B104. First, we phenotyped the heat stress responses of maize plants at the whole-plant level under controlled environment. Second, we conducted a subset of experiments to a) examine variation of heat stress treatment performed in greenhouse vs. in walk-in growth chambers, b) test how to effectively coordinate different physiological and biochemical measurements and sampling process during the heat treatment, and c) train students for sample collections, lipid extraction, membrane stability measurement, gas exchange and chlorophyll fluorescence measurements. Third, we conducted a time-course experiment to measure chlorophyll fluorescence and leaf-level net carbon assimilation of young and mature leaves. Objective 2: Identify the genetic loci that contribute to the differential heat stress response through meta-analysis of two populations. Two mapping population are being developed. The first one, B76/B106, is a doubled haploid (DH) population with 234 individuals. The second one, B76/NC350, is a recombinant inbred line population with 126 individuals. As a remedy to the relatively small size of the second population (due to the adaptation issue from NC350), we have also developed a third population, NC350/B106, with 150 individuals. Seed increase will be conducted in summer nursery at Ames Iowa in 2017.
Publications
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