Photosynthetic Characteristics And Quantitative Proteomics Analysis Of Maize And Rice Leaves

The photosynthesis of C4 crops has no midday depression.And C4 crop leaves have a larger leaf density than C3 crop leaves,which is favorable for the rapid transport of photosynthate and reduces the feedback inhibition of photosynthesis to photosynthesis.Therefore,C4 crops have higher photosynthetic efficiency than C3 crops.It is of great significance to study the mechanism of C4 photosynthesis,the occurrence and development mechanism of C3 leaf veins to further understand the molecular mechanism of high light efficiency and create high light efficiency germplasm.In this study,the method of proteomics was used to study the single peak photosynthetic rate of C4 maize and the expression during the occurrence and development of the leaf vein in the C3 plants,to explore the molecular mechanism of photosynthesis and the occurrence and development of leaf vein.Plant leaves have a different pattern of photosynthesis rate under diurnal light regulation.Maize leaf showed a single peak pattern without midday depression when the light intensity reaches a maximum.This mechanism is contributed to high efficient photosynthesis in maize leaf.To understand the molecular basis of this process,an iTRAQ base proteomics analysis was performed to reveal the dynamic level pattern of proteins related to photosynthesis reaction.As light intensity changes,photosynthesis related pathways do not just belong to only a single expression pattern.Steady,single-peak and double-peak patterns were discovered in maize leaf protein expression.Antenna proteins displayed a steady pattern in maize leaf.However,photosystem,carbon fixation and citrate pathways were highly controlled by diurnal light intensity.Almost enzymes in limiting step of these pathways were major regulated site,such as isocitrate dehydrogenase.It suggests the mechanism that maize leaf optimizes the photosynthesis light reaction and carbon fixation other than light harvest to adapt the diurnal light intensity in the protein level.Leaf veins play critical role in resource supplication and photosynthate translocation thus it is considered as important agricultural traits for crop breeding.The rice minor veins are parallel produced along all the part of leaf from base to tip.To understand the process of minor vein development,anatomy analysis was performed to reveal the initiation and development of minor vein in rice leaf.The frequency of minor vein initiation follow a decreased tendency from leaf base to tip.An iTRAQ based proteomics analysis was performed to rice leaf sections.Photosynthesis and carbon fixation related proteins showed high level in the middle part of leaves.Furthermore,marker proteins were identified correlated with the frequency pattern of minor vein initiation.Sucrose degradation and starch synthesis were separated to initiation and mature part of minor veins respectively.It suggests different source-sink activity in the initiation and mature parts of minor veins in terms of photosynthate translocation.The identified proteins are candidate markers for small vein initiation in rice leaves.Sucrose synthase is a marker of the initiation of small veins.Proteins associated with the initiation of small veins are candidate targets for improving rice leaf density.