A TRANSGENIC MUTANT DEFECTED IN CELL ELONGATION AND CELLULAR ORGANIZATION DURING BOTH ROOT AND SHOOT DEVELOPMENT IN LETTUCE, Lactuca sativa.

• Main Authors: Chuan-I Li, 李專義
• Other Authors: Chang-Hsien Yang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/74861479191085884421

碩士 === 國立中興大學 === 農業生物科技學研究所 === 87 === A recessive mutation affecting both root and shoot development was isolated from transformants of lettuce cv. Diana co-transformed with maize Ac transposase and Ds . All of the mutants were co-segregated with the T-DNA containing Ac transposase indicating that the mutation was caused by insertional mutagenesis. Mutations in this novel genetic locus, designated as ABNORMAL ROOT AND SHOOT (ARS), showed a dwarf phenotype by producing short thick roots,short hypocotyl and abnormal filamentous leaves without any futher reproductive development . The anatomical analysis revealed that the ars mutant root phenotype is primarily due to the lack of cell elongation and to the abnormal increased cell numbers in the cortex region in the roots . ars mutants are able to initiate normal leaf primodia ,however the cell elongation and cellular organization of the developing leaf primodia is impaired and results in sequentially abnormal development of the leaf. These findings indicate that the ARS gene represents a novel class of gene which is strictly required for cell elongation as well as cell orgnization in the same type of cells after meristematic division in both the root and shoot. ars mutants also display highly photomorphogenic development in darkness by producing open cotyledons, developing vegetative leaves, and short hypocotyls. This suggests that the ARS gene may also be involed in the repression of photomorphogenic development in the absence of light. ars mutations can not be normalized into wild-type plants by exogenous application of phytohormones such as gibberllin(GA) or brassinosteriods, indicating mutation is not likely impaired in the biosynthesis or perception of these two hormones. A strategy based on IPCR was used to isolate a 356 bp genomic DNA fragment flanking the insertional site of T-DNA. Using this genomic DNA to futher clone ARS gene is in progress and will also be presented.