Effect Of Multidrug Protein PCaP2 In Arabidopsis Thaliana Under Drought Stress

Drought is the most common abiotic stress factor in agricultural production,which seriously restricts plant growth,development and productivity.Therefore,it is necessary to study the drought resistance mechanism of plants.Arabidopsis plasma membrane-associated Ca²⁺-binding protein-2?PCaP2?,which is a multifunctional protein found in Arabidopsis thaliana.In previous studies it was demonstrated that it also plays an important role in the binding of microtubules?MTs?and the regulation of plant cytoskeleton,so it also known as microtubule-associated protein-18?MAP18?.This study focuses on the function of binding Ca²⁺,so called it PCaP2.Some studies have shown that PCaP2 regulates the growth of Arabidopsis root hairs,pollen tubes,and directional cells.In addition,drought promotes the transcription of PCaP2 and induces the increase of cytoplasmic Ca²⁺concentration.PCaP2,as a calcium-binding protein,can interpret Ca²⁺-induced stress signals and cascade in the cells,triggering more stress mechanisms.Therefore,PCaP2 is an important multifunctional protein that can regulate many physiological activities of Arabidopsis and it has great significance for the in-depth study of PCaP2 function.However,the specific mechanism of PCaP2 regulating plant adaptation to drought is not clear.In this study,Arabidopsis wild type?WT?,pcap2,and overexpressing?PCaP2-OE?or knockout?PCaP2-RNAi?of PCaP2 were used as experimental materials.By identifying the expression pattern of PCaP2 under drought stress,observing the germination and growth status of WT,pcap2,and two transgenic lines PCaP2-OE and PCaP2-RNAi under drought conditions,counting root hair length and water loss of each line,and determining the effects of PCaP2 on relative expressions of drought-induced genes,including KIN1,KIN2,RD29A and SnRK2s,to reveal the specific role of PCaP2 under drought stress.The main results are as follows:?1?Drought treatment can significantly induced PCaP2 expression;?2?PCaP2 is located in the true leaves,cotyledons,hypocotyls,and roots of Arabidopsis;?3?Under normal conditions,the germination rate of PCaP2 transgenic seeds and WT seeds were basically the same.Under drought stress medium,PCaP2 could positively control the germination of Arabidopsis seeds and their inhibition was significantly less than pcap2 and PCaP2-RNAi;?4?Under normal conditions,the growth of PCaP2 transgenic lines and WT were basically the same.However,under drought stress,the growth of each line was inhibited,but the inhibition of PCaP2-OE plants by drought was more less than that of pcap2 and PCaP2-RNAi.?5?Under normal conditions,the root hair length of pcap2 and PCaP2-RNAi seedlings was shorter than that of WT.After drought stress,root hair growth of all seedlings was more inhibited by drought,and the root hairs of pcap2 and PCaP2-RNAi were further shorter than those of WT;?6?Under drought stress,PCaP2-OE plants had better water retention and higher water content than WT,while pcap2 and PCaP2-RNAi had poor water retention and low water content;?7?The deletion of PCaP2 inhibited the induced expression of drought-induced genes under drought conditions,including SnRK2.2,-2.3 and-2.6 and KIN1,KIN2,RD29A.In summary,drought induced the expression of PCaP2 in Arabidopsis.PCaP2 can increase the germination and growth and water status of Arabidopsis under drought conditions,and induce drought-induced genes,thereby enhancing drought adaptability in Arabidopsis thaliana.