Cloning And Functional Analysis Of Protein Kinase Gene ZmPto1 In Maize

Protein kinase plays an important role in plant resistance pathway.Gene Pto encodes a serine-threonine protein kinase and is the first resistant gene following the law of gene-for-gene interaction.Pto-overexpresion transgenic tomatoes varieties confer resistance to Pseudomonas syringae pv.tomato.Pti-like gene ZmPti1 has been cloned in maize.But Pto interacts with Pti1 and phosphates Pti1 to active signal conduction pathway in tomato.We cloned a full-length cDNA,a homologous Pro protein and called it ZmPto1 (EU375843).The ZmPto1 protein includes a Ser/Thr domain,encodes 407 amino acids with an estimated molecular mass of 45.489 KD and an isoelectric point of 5.85.Phylogenetic analysis showed that ZmPto1 is close to rice protein kinase gene in inheritance.Semi-quantitive RT-PCR analysis showed that the ZmPto1 expression was induced by abscisic acid(ABA) and mannitol,in different tissues the ZmPto1 showed different transcriptional expression patterns.We haven't detected ZmPto1 expresses in mature leaves,tassels and coleoptiles.The expression is relatively low in ovaries and young leaves but high in roots and silks.These results suggested that ZmPto1 may play multiple roles in abiotic stress pathways,as well as in plant reproductive development.For further studying the biology function of ZmPto1,we constructed plant expressing vector with 35S promoter and bar selective marker to overexpress ZmPto1 in Arabidopsis. The plants survived under 1.2%o herbicide treatment are positive plants.PCR analysis showed the positive plants are transgenic plants.For determining the role of ZmPto1 in signal conduction pathway in maize.We proved that ZmPto1 interacts with ZmPti1(GenBank:AY708048.1) with LexA two-hybrid system.ZmPti1 encodes a salt inducible protein.Overexpression of ZmPti1 gene in Arabidopsis showed that the transgenic plants can enhance the salt resistance.So we guess that ZmPto1 is the upstream regulatory gene in signal conduction pathway and interacts with ZmPti1 to induce salt durable signal pathway. ZmPto1 is the upstream regulatory gene and possibly participates in other signal pathway.We proved that ZmPto1 interacts with ZmPti1-1(GenBank:EF158035.1)in yeast two hybrid system.Though it is proved that overexpression of ZmPti1 gene in Arabidopsis showed no phenotype,it is showed that ZmPto1 interacts with several proteins and participates in other signal pathway.