Rapid Assessment Of Seed Vigor Of Coffee And Corn Seeds Based On Direct Mass Spectrometry

Seed vigor,an important indicator of the seed quality,is the sum of properties that determine the activity and level of performance of seed lots of acceptable germination in a wide range of environment.Currently,there are some seed vigor test methods,such as ATP determination,the germination rate determination,seedling growth determination,enzyme activity measurement,and so on.The results shown that,those methods can correctly predict intuitively seed vigor,while generally,these methods show some shortcomings,for example,workload and high costs,inefficient,slow,and destructive for seeds.In order to meet the rapid,accurate and non-destructive detection acquired by modern agricultural technologies,emerging technologies continue to be applied to the seed vigor test.Recently,direct mass spectrometry methods were developed,which exhibit more rapid detection speed and more extensive application area.This paper used surface desorption atmospheric pressure chemical ionization mass spectrometry(DAPCI-MS)and extractive electrospray ionization mass spectrometry(EESI-MS)technology in direct seed vigor determination of coffee and corn seeds,combined with multivariate analysis methods,to achieve rapid evaluation of coffee and corn seeds.The main contents and results were as follows:1.In this paper,we used artificial accelerated aging method to obtain coffee and corn seeds with different vigor.These seeds were measured by standard germination test,DAPCI-MS and EESI-MS after aging,with unaged seeds as controls.2.By standard germination test,understand the variation of the seed germination and seed vigor index during aging.We found that significantly differences in seed germination index and vigor index between unaged and aged coffee seeds,as well as significantly differences in seed vigor index between unaged and aged corn seeds.For different aging times,the seed germination index and vigor index showed a downward trend,and for the seeds with a certain aging time,the germination index and vigor index were dropped to 0,showed that seeds with the seed vigor the aging time decreased until completely lost during aging treatment.The correlation analysis of seed vigor index and aging time found that vigor index and aging time were significant negative correlation,showed that different aging time make the seed formation different seed vigor levels.3.In order to distinguish the coffee seeds with different vigor quickly,DAPCI-MS was performed to obtaining chemical fingerprints directly from the surface of the coffee seeds.In all spectra,more mass spectral peaks were observed between m/z 100 and 400 than larger than m/z 400 mass.Signal peak m/z 55,274,302,318,400,473 and 489 were available in all the coffee seed samples,in which the abundance of m/z 274 and 318 were the strongest,m/z 473 was decreased first and then reinforced the downward trend during aging.The experimental findings demonstrated that in the positive ion mode,three principal components were extracted by PCA,and their cumulative contribution rate was 92.2%.Coffee seeds with the same vigor were packed closely together in CA,and its test accuracy was100%.In DA,the return discriminant ratio for the training muster was as high as100%,and the cross validation analysis success rate was 100%.There are some differences between different vigor of seed,because coffee seeds are rich in the chemical composition,these materials or content may change during aging.4.This paper used EESI-MS to obtain chemical fingerprints from the aqueous extract of coffee seeds.It can be seen from the spectra,the spectrum of coffee seeds with different aging time have a greater similarity,signal peak m/z 113,195 and 217have a strong abundance in all spectra.Which the m/z 195[M+H]~+ion tandem mass spectrometry for qualitative analysis,compared the characteristic fragment ions and references inferred as caffeine.The experimental findings demonstrated that in the positive ion mode,three principal components were extracted by PCA,and their cumulative contribution rate was 99.3%.Coffee seeds with the same vigor were packed closely together in CA,and its accuracy was 100%.In DA,the return discriminant ratio for the training muster was as high as 100%,and the cross validation analysis success rate was 100%.Cell membrane damage of seed during aging induces intracellular soluble substances leakage,varying in degrees of damage to the cell membrane coulpled with different seed vigor.The amounts of soluble substance leakage are varied,so this method can be used for seed vigor test.5.In order to distinguish the corn seeds with different vigor quickly,DAPCI-MS was performed to obtain chemical fingerprints directly from the surface of the corn seeds.In all spectra,more mass spectral peaks were observed between m/z 50 and 120,with relatively strong signal intensity.Less mass spectrum peaks were greater than m/z 120 for corn seeds after aging 2d,with lower signal intensity.The mass spectral peak signals were enhanced for corn seeds after aging 4d.Signal peak m/z 73,87,100,116 and 362 were in all corn seed samples,with relatively stronger intensity.The results demonstrated that in the positive ion mode,three principal components were extracted by PCA,and their cumulative contribution rate was 85.4%.Corn seeds with the same vigor were packed closely together in CA with the accuracy of 100%.In DA,the return discriminant ratio for the training muster was as high as 98.7%,and the cross validation analysis success rate was 100%.6.This paper used EESI-MS to obtain chemical fingerprints from the aqueous extract of corn seeds.Mass peak m/z 104 in unaged corn seed showed the highest signal abundance,which was declined for corn seeds after aging 2d.Mass spectral peak m/z 113 in unaged corn seed was lower.After aged from 2d to 10d,the signal was significantly increasedand was then declined.Mass peak m/z 115 for seeds from unaged to 8d aged corn seeds were presented lower signal,and for seeds more than10d aged,signal was significantly enhanced.The experimental findings demonstrated that in the positive ion mode,three principal components were extracted by PCA,and their cumulative contribution rate was 62.9%.Corn seeds with the same vigor were packed closely together in CA with the accuracy of 100%.In DA,the return discriminant ratio for the training muster was as high as 100%,and the cross validation analysis success rate was 100%.Seeds aging is caused by many reasons,including the loss of membrane integrity,reduce of synthesis energy metabolism,damage of RNA and protein,degradation of DNA and so on.During seed aging,content and composition of alcohols,aldehydes,ketones,acids,lipids,proteins,starch and other material as well as its internal ultrastructure of seeds contained inside changes,and these chemicals are leaked partly to seed surface.Therefore,direct mass spectrometry can understand the metabolites during aging,and construct the relation between the seed vigor and substance qualitative and quantitative analysis.In this paper,we used home-made DAPCI and EESI mass spectrometry as a research platform,and performed a systematic study of different vigor of coffee and corn seeds.The study provides a basis for establishing a new detection method of seed vigor with simple operation,fast detection speed,and non-destructive and sensitive to seeds.