| Water is an essential element of life activities.Water shortage in plants can cause their growth and development defects,and severe water shortage can lead to plants' death.Drought is one of the main factors limiting agricultural production at present,so it is important to study how plants respond to drought stress to improve crop drought resistance and improvement.Calcium is not only a necessary nutrient for plants but also an important second messenger in plants,which is very important for the signal transmission from external stimuli to cytosol biological message.Under normal conditions,the intracellular calcium ion concentration of the plant will be maintained at a very low level.When the receptor/sensor senses external stimuli,the calcium channel on the membrane will open and calcium ions will enter the cytoplasm from the extracellular or intracellular calcium reservoir.Then the calcium concentration in the cytoplasm increased to produce a calcium signal,which in turn continues to transmit the stimulation signal to the downstream,regulating the cells to respond to the stimulation signal.At present,OSCA1 is a first calcium ion channel that is sensitized to external osmotic stress in the plant identified by osmotic induction of intracellular calcium signal loss.But it is unclear what effect the mutation of OSCA1 will have on plants grown under normal conditions and drought stress conditions.And for the plant to feel the external osmotic stress caused by intracellular calcium signaling and its transmission mechanism,the current understanding is not very thorough.This study is mainly divided into two parts: the first part is mainly to study the effect of OSCA1 on plant growth under normal and drought conditions;the second part is mainly through the use of in vivo expression of jellyfish fluorescent protein Aequorin(AQ)as the calcium indicator in Arabidopsis thaliana.And the mutants were used to screen for components on the osmotic induction calcium signaling pathway.The main research results are as follows:1.It was found that the survival rate of osca1 was significantly lower than that of wild type under severe drought stress.And after several generations of planting,the coverage of osca1 in the population gradually decreased,and the loss rate of osca1 was higher under drought conditions than well water conditions,indicating that osca1 was not dominant in the population and was very sensitive to drought,even mild drought.2.The osca1 mutants have high photosynthetic rate and low water use efficiency under normal conditions,and it shows a drought-tolerant character.In terms of yield,the yield of osca1 is lower than that of wild type,and the seed abortion rate is high.3.The mutants with osmotic stress-induced calcium signal defect selected from the EMS mutagenesis library were genetic mutants with checking three generations at least and the F3 lines with mutant phenotype were used for mapping.Plants with sorbitol-induced calcium signal deletion were screened and DNA was extracted for the second generation whole genome sequencing.4.Based on the analysis of the sequencing data,the target gene is coarsely located.Then,according to the single nucleotide polymorphisms(SNPs)in the sequencing results as a molecular marker,the polymorphism marker analysis was carried out,and the target gene was finely mapped to some canditate genes.Then the plant expression vector was constructed and transferred into the mutant for subsequent functional complementation And verification.Due to time constraints,there is currently no genetically modified plant material.Through the above studies,we have a certain understanding of the role of plant osmotic sensor OSCA1 in plant growth and development,and screened a possible component involved in calcium signaling pathway induced by the osmotic stress.It is helpful to further study the calcium signaling pathway of plant osmotic stress and provide some theoretical basis for plant drought resistance breeding at the same time. |
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