ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The DP1 variegated mutant of Nicotiana tabacum contains translationally defective plastids in its white (W) leaf sectors. In the present study a second type of pigment-deficient sector displaying a pale-yellow color (Y sectors) was discerned. Chlorophyll and carotenoids contents in both leaf sectors are very low, although the Y sectors contain twice the carotenoid content of the W sectors. Rubisco large subunit polypeptide content is low in the W sectors, while in the Y sectors its content is comparable to that in the green sectors. However, both leaf sector types do not show photosynthetic activity under ambient CO2 concentration. The W and Y sectors exhibit 40 and 50% reduction in the level of the mRNA encoding the peroxisomal glycolate oxidase (GLO) enzyme, respectively. However, in the W sectors GLO activity and protein levels reached only 30% of that in the green sectors while in the Y sectors they almost reached the green sectors levels. It is suggested that the reduction in GLO mRNA levels in the Y and W sectors is resulted from inhibition of the putative plastid to nucleus signal. Post-transcriptional mechanism(s) that also regulate GLO gene expression may explain the discrepancies between GLO mRNA and GLO protein levels, as observed between the W, Y and green leaf sectors of the DP1 mutant.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1034/j.1399-3054.2000.110116.x
