Characterisation of nuclear gene controlled yellow stripe mutant of Pennisetum glaucum (L.) R.Br.

Abstract

The plastid mutant of pearl millet exhibiting a pattern dependent material inheritance was characterised in terms of chlorophyll a/b ratios, the levels of ribulose1,5-bisphosphate carboxylase (RuBPCase) and phosphoenolpyruvate carboxylase (PEPCase). The chlorophyll content varied from leaf to leaf in variegated plants while no consistent differences in chlorophyll a/b ratios were evident. RuBPCase activity was lacking in yellow seedlings and yellow tissue from variegated plants and the enzyme levels were lower in variegated plants compared to that of green sibs and the RuBPCase activity in variegated leaves was dependent on the extent of green tissue in the material irrespective of their genotype. The PEPCase levels in the yellow and green seedlings were similar while yellow tissue had lower levels compared to green tissue within the variegated plants. Sedimentation analysis of the soluble protein fraction from the green and yellow tissues revealed lack of RuBPCase protein (19.45S) in the yellow tissue. Furthermore, the SDS-polyacrylamide gel electrophoresis revealed absence of the larger subunit (55 kDa) of RuBPCase. These observations are consistent with the information on ultrastructural and molecular changes associated with the altered plastids and their genetic basis in the same mutant.