ISSN:
1617-4623
Keywords:
Key words Homeobox gene
;
In situ hybridization
;
Leaf morphology
;
Transgenic tobacco
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Transgenic tobacco plants were generated carrying a rice homeobox gene, OSH1, controlled by the promoter of a gene encoding a tobacco pathogenesis-related protein (PR1a). These lines were morphologically abnormal, with wrinkled and/or lobed leaves. Histological analysis of shoot apex primordia indicated arrest of lateral leaf blade expansion, often resulting in asymmetric and anisotropic growth of leaf blades. Other notable abnormalities included abnormal or arrested development of leaf lateral veins. Interestingly, OSH1 expression was undetectable in mature leaves with the aberrant morphological features. Thus, OSH1 expression in mature leaves is not necessary for abnormal leaf development. Northern blot and in situ hybridization analyses indicate that PR1a-OSH1 is expressed only in the shoot apical meristem and in very young leaf primordia. Therefore, the aberrant morphological features are an indirect consequence of ectopic OSH1 gene expression. The only abnormality observed in tissues expressing the transgene was periclinal (rather than anticlinal) division in mesophyll cells during leaf blade initiation. This generates thicker leaf blades and disrupts the mesophyll cell layers, from which vascular tissues differentiate. The OSH1 product appears to affect the mechanism controlling the orientation of the plane of cell division, resulting in abnormal periclinal division of mesophyll cell, which in turn results in the gross morphological abnormalities observed in the transgenic lines.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02174339
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