Proteomic study on protein expressions of pollinated and 2,4-D treated kernels in maize (Zea mays L.)
Date Issued
2005
Date
2005
Author(s)
Chang, Yu-Hsin
DOI
zh-TW
Abstract
Auxin is one of key regulators for physiological processes during maize caryopsis growth and development, including cell division, cell enlargement, and dry matter accumulation. The main objective of this study was to study the molecular basis of auxin’s function on maize caryopsis development, using proteome analysis technique.
A maize cultivar (Tainan 22, TN22) was grown in the field or greenhouse. At silking, maize ears were either treated with a synthetic auxin 2, 4-D or hand pollinated. And kernels which were not treated with 2, 4-D and handed - pollination were used as the controls for comparison. Kernels were sampled at 1, 3, 5, 9, and 12 days after treatment or pollination, and than stored at -80℃ for analysis. Changes of fresh weight, dry weight, water content, sugar content, alcohol soluble protein, and starch staining pattern were measured. To determine the expression patterns of maize kernel proteins, a high resolution two - dimensional gel electrophoresis was used. Differential expressed proteins were further sampled and identified by ESI-Q-TOF MS.
The result showed that 2,4-D could induce a parthenocarpic-like growth. The rates of fresh weight, dry weight , water content, and sugar accumulation in 2,4-D treated kernels were faster than that of pollinated kernels during early developing stage (1~5 days after treatment). After 5 days of development, the physiological processes were decreased. In morphological observation, the auxin could promote pericarp and nucellus growth. However, no endosperm organ and the accumulation of starch and storage protein (zein) could be detected in 2,4-D induced parthenocarpic kernels. This suggested that auxin can promote a fast growth of unpollinated maize caryopsis during early developing stage, but it could not enable the caryopsis to develop into a functional seed.
With 2-D gel analysis, several proteins were up-regulated by 2,4-D and were identified, including: germin-like protein 1, calmodulin, glycine-rich RNA binding protein 1, and profilin. Germin-like protein 1 expressed in kernels of 3 days after 2,4-D treatment and in kernels of 3 days after pollination (DAP). The other proteins expressed later in kernels of 5 days after 2,4-D treatment and in kernels of 5 DAP. The function of these proteins may be correlated with the auxin induced signal transduction and rapid tissue growth. In pollinated kernels several glycolytic related enzymes were identified from kernels at 12 DAP, for example, G 3-P dehydrogenase and fructose bisphosphate aldolase. These proteins have been suggested to be involved in energy supply for the growing cell activity. Significant expressions of chitinase A and 22K antifungal proteins were interestingly observed in unpollinated and degenerating kernels, which might be related to the protection of infection during senescence of caryopsis without pollination.
In this study, 40 proteins in kernel of early developing stage were identified. The proteome profiles will facilitate future studies addressing the effects of genetic and environmental factors on the development and quality of maize kernels.
Subjects
玉米穎果發育
生長素
單性結果
蛋白質體學
maize kernel development
auxin
2,4-D
parthenocarpy
GLP1
profilin
Type
thesis
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