1. The document discusses a study analyzing the metabolite profiles of maize stem extracts using direct infusion electrospray ionization mass spectrometry (DIESI-MS). Samples were collected from different maize genotypes grown under varying environmental conditions.
2. Metabolite profiling was conducted to better understand the function of the maize stem and how metabolites change under different field conditions. DIESI-MS was used for its high-throughput capabilities.
3. Preliminary results found differences in metabolite signatures between genotypes and environmental treatments. Amino acids like lysine, valine, and serine showed clear signals. Further analysis of the metabolic profiles may help explain the genotype-phenotype relationship in maize
Technical efficiency of smallholder maize growers in Nepal
Metabolic phenotyping of maize stem extracts using DIESI-MS
1. 1st. National Workshop on
Fodder Maize
“Metabolic phenotyping
of maize stem extracts
using DIESI-MS”
MC Martín García Flores
Supervisor: Dr. Axel Tiessen
Lab Metabolomics & Molecular Physiology
Irapuato, Gto., January 23, 2013
2. Outline
• Introduction
– Forage maize
– Genotype-Phenotype dilemma
• Experimental strategy and Methods
– Workflow Metabolomics
– Harvesting and sample prep
– Mass spectrometry (DIESI-MS)
• Control experiments
• Results
– Spectral comparisons, heatmaps
3. Forage production
2012 Year Forage production
1600000
1400000
1200000
1000000
Ton
800000
600000
400000
200000
0 QUERETARO
AGUASCALIENTES
PUEBLA
MEXICO
GUANAJUATO
ZACATECAS
CHIHUAHUA
DURANGO
COAHUILA
JALISCO
State
http://www.siap.gob.mx/
22/01/2013
12. Biological questions
What is the function of the stem in
the maize plant?
Which metabolites change under
different field conditions?
Experimental design (Lattice)
Texcoco: 11 Genotypes, 6 biological samples, 3 technical
samples (Low Nitrogen and Normal Nitrogen)
Tlaltizapan:14 Genotypes, 6 biological samples, 3
technical samples (Water stress and Well watered)
14. Sampling
Experimental field trial
Maize stem sampling
Physiological data recording
Grounding and collection of extracted
juice sample, 1 ml
Freezing in 96-well microplates, dry ice
for 30 s. and storaged in liquid “N”
(-80 °C).
15. Sample preparation
Filter 0.45 µm mesh PVDF; 10 µL sample and
990 µL De-Ionizade H2O (1:100 dilution).
Add 25 µL formic acid to 475 µL sample, mix 3
min and Read: DIESI-MS.
Defreezing in ice bath for 1 hr
Centrifugate for 10 min, 4000 rpm, 4 °C.
Supernatant filtration: 0.45µm mesh
PVDF, activated carbon treatment, 100
µL aliquotes in 96-well microplates
Freezing (-18 °C) before DIESI-MS
García-Flores et al., 2012
16. Data acquisition
DIESI Conditions
Water micromass Q/Z
spectrometer
ES (+) source.
Voltages: Capillary (Kv) 3.0 Temperatures.
Cone (V) 60 source ·C 80
Extractor (V) 3 desolvation ·C 150
Rf lens (V) 0.5
Gas flow.
Desolvation (L/hr) 250
Cone (L/hr) 50
Syringe.
Pump flow (µl/min) 10
Analyzer.
LM resolution 15
HM resolution 15
Ion energy 0.5
Multiplier 650
García-Flores et al., 2012
17. Direct infusion electron spray ionization
mass spectrometry (DIESI-MS).
Waters micromass (Z/Q).
Mass spectrometer (m/z).
41. Evaluating the physiological state of maize (Zea mays
L.) plants by direct-injection electrospray mass
spectrometry (DIESI-MS).
Martín García Flores; Sheila Juárez Colunga; Josaphat Miguel Montero Vargas; Janet
Ana Isabel López Arciniéga; Alicia Chagoya; Axel Tiessen and Robert Winkler.
Molecular Biosystems García-Flores et al., 2012
42. Conclusions
DIESI-MS has high throughput. It is the cheapest and
fastest MS strategy. We have successfully set up the
method at CINVESTAV.
We can detect >200 of different ms peaks. We can
measure more that 80 samples per day.
Some peaks vary acording to Gen and Env effects
Biochemical phenotyping of maize stem fluids enables
the rapid evaluation of the physiological state of plants.
It also allows to discriminate between genotypes (
breeding)
Metabolic heatmaps are useful for MS data
representation
43. Perspectives
The method will be applied at large scale for
investigating the metabolic stress response of various
Zea mays L. genotypes.
We hope we can detect biomarkers for selection
Derived metabolic markers can complement the DNA
based markers for breeding.
44. Acknowledgments
• CIMMYT MasAgro-IMIC
– Dr. Marc Rojas (IMIC)
– Dr. Felix San Vicente (CIMMYT)
• CONACYT Grants
• Dr. Axel and Dr. Robert
• Laboratory team: Mayela, Andrés, Adrián,
Erandi, Sheila, Obed, Iván, Julio, Viviana,
Daniel, etc