Cloning And Functional Analysis Of Strip Rust Resistance Related Gene TaLecRK4.3 From Wheat (Triticum Aestivum.L)

Stripe rust in wheat, which is caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive fungus diseases in the world. Nowdays, it has become one of the major constraints to wheat production. It can lead to 50-60% wheat yield decrease in prevailing years. Thus, development of resistant varieties is the best way to control this disease. And, discovery and cloning of new resistance genes will be of great significance in resistant varieties breeding.Plant receptor-like kinase (RLKs) plays an important role in response to abiotic and biotic stresses. Lectin-like receptor kinases (LecRKs), one member of RLKs family, contains the same conserved domain as RLKs. Lectins are proteins possessing at least one noncatalytic domain, which can bind reversibly to specific mono-or oligo-saccharides. Present researches suggested that LecRKs could be involved in plant defense response, stress and wound.TaLecRK4.3, a hypothetical resistance-related gene, was detected during searching for the candidate gene of Yr26 by genechip hybridization using cDNA fromthe susceptible and resisitant varieties cDNA. It was found that the probe TaAffx.83378.1.S1_showed differentially pattens between the resistant materials and the susceptible wheat Yangmai158 both at 12 h and 36 h after the Pst inoculation. Based on the sequence of TaAffx.83378.1.S1, the PCR for RACE technology was designed and then the the full length sequence of the gene from the resisitant varieties 92R137 cDNA was cloned. Full length of the cDNA is 2120bp, of which 2068bp form the open reading frame encoding 667 amino acides. According to the specific structure and the sequence analysis in the model species, the gene was designated as TaLecRK4.3. Then TaLecRK4.3 has been located in chromosome 1B using a series of Nulli-tetrasomic lines of cv. Chinese Spring. The homologues of the Lectin domain of TaLecRK4.3 were all cloned in both the resistant and susceptible materials, and the sequencing result suggested that there were three different copies of TaLecRK4.3 in the resistant 92R137, including TaLecRK4.3-1, TaLecRK4.3-2 and TaLecRK4.3-3, however, only TaLecRK4.3-1 was detected in both resistant materials (92R137 and Y263). So, it was proposed that TaLecRK4.3-1 was the upregulated gene induced by Pst CYR32 in resistant wheat varieties. The results of qRT-PCR and RT-PCR indicated that TaLecRK4.3 was up-regulated by the Pst CYR32 inoculation, SA and ABA. TaLecRK4.3 perhapsplays a putative role in the defense resistance to Pst Probably through the signal pathway of S A and ABA.To analyse the gene function of TaLecRK4.3, a pBi220-HA-TaLecRK4.3-1 over-expression vector was constructed and transformed into the susceptible wheat variety Yangmail58 in 2012 and 2013 respectively. One transgenic line of T1 generation has been detected with increased resistance to the Pst CYR32. Twenty six positive transgenic plants have been identified by PCR analysis from the population of regenerated plants developmed in 2013, which are the valuable resources for the functional analysis of TaLecRK4.3 in the future research.