Alteration of tobacco leaf morphology by overexpressing NTPHAN, SCR and WOX3

• Main Authors: Wei-Yi Lin, 林維怡
• Other Authors: Li-Fei Liu
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/51513965678251298905

碩士 === 臺灣大學 === 農藝學研究所 === 95 === Leaves are the major photosynthesis and gas exchange organ of plants. They originate from the peripheral zone of the shoot apical meristem (SAM), stem cells change the rates and the planes of cell division, and are recruited into the leaf primordia. A number of transcription factors are involved in the regulation of leaf development and extension. In this thesis, three genes related to the development of plant organs were studied, which are NTPHAN, SCARECROW (SCR) and WOX3. PHANTASTICA (PHAN) from Antirrunhum and NSPHAN, the Nicotiana ortholog of PHAN, regulates the development of adaxial part of leaves. SCR regulates the periclinal cell division in the cortex of roots and stems to form cortex and endodermis. WOX3 specifies the cell fate at the margins of cotyledonary primordia and regulates the rate of cell division in the margins of meristem in Arabidopsis. The effects on the leaf morphology of these three genes were studied by transformation into tobacco. These genes, driven by CaMV 35S promoter, were constructed on the binary vector, pCAMBIA1302. The construct was individually or co-transformed to tobacco (Nicotiana tabacum) by Agro-transformation method. Three kinds of transgenic lines were obtained that overexpressed SCR, or WOX3, or NTPHAN and SCR. The transgenic plant of over-expressed WOX3 had upwardly curled leaves caused by disrupting the extension of upper epidermis. Also it had distorted veins and abnormal mesophyll. The transgenic plant of over-expressed SCR had an ectopic leaf from the vein at the abaxial side. Abnormal cell division can be found at some regions of mesophyll. Its leaves had larger ratio of length and width than non-transgenic plants’. The transgenic lines that over-expressed NTPHAN and SCR developed narrower leaves at first and then the leaves expanded but with wave-like edge. Cells in the mesophyll were arranged compactly without adaxial-abaxial polarity. It was also found that in most transgenic plant leaves, the expression of NtPHAV, which promotes the adaxial identity in the development leaf, was enhanced. This result suggests that these three genes involved in development at the different growth stages or in different organs possibly by affecting the expression of leaf developmental genes.