Cloning And Functional Analysis Of PtCaM In Populus Tomentosa Carr

Wood formation is a complex process composing many biological events, of which are strictly regulated by corresponding genes. In order to improve wood quality with molecular breeding techniques, it is necessary to deeply understand the molecular mechanisms of wood formation, to study the function of key genes controlling wood formation and interaction mechanisms of these genes. Ultimately, it is desirable to effectively manipulate the key genes involved in wood formation and produce the genetically modified trees with improved wood quality. The previous reports in model plant P. tomentosa revealed that PtCaM might high involved the development and differentiation of vascular tissue. To explore the role of PtCaM involved in growth and development of trees, PtCaM was isolated using reverse transcriptase-PCR method. The role in wood formation of PtCaM in wood planty poplar were studied by using gene overexpression. The results showed that PtCaM have important roles in cambial activity and wood formation processes. The major findings are described as the followings:A cDNA clone encoding PtCaM was isolated from the cDNAs prepared from mRNAs cambial zone of Populus tomentosa by the reverse transcriptase-PCR method. The cDNA is 642 bp in length with an open reading frame which is capable of encoding a protein of 199 amino acid. The deduced amino acid sequence of the PtCaM shared high identity with that from other plants.To explore the role of PtCaM in cambial activity and vascular tissue development of PtCaM, The over-expression vector of pBI121-35s-PtCaM was further constructed and introduced into hybrid poplar 84K via Agrobacterium tumefaciens-mediated leaf disk transformation method. The real time quantitutive PCR analysis showed the gene was over-expressed in transgenic poplars and the growth and development of these plants was enhanced. ANOVA analysis indicated there were significant differences on height, ground diameter and mature leaves between non-and transgenic plants.Anatomical studies of stem of wild and transgenic poplar showed xylem zone of transgenic plants was enlarged. The present study suggestes that over-expressed PtCaM stimulate the cambium, which leads to the large quantity of xylem cells, and affacts the growth and development of plant.