Changes in zein mRNA stability during maize kernel development

The in vitro stability of zein mRNAs was evaluated in the process of kernel development of wildtype acid opaque2 (o2) maize 15, 20, and 30 days after pollination (DAP). Using a combination of the reverse transcription-polymerase chain reaction and the ommp system, we showed that, in developing wild-type kernels, the difference between the mRNA stability of two major zein fractions increased: the mRNA for 19-kD zein was stabilized and that for 22-kD zein destabilized. O2 mutation resulted in the stabilization of both mRNAs at the early stages of kernel development (15 and 20 DAP); later, the stability of both mRNAs dropped. Increased sucrose and RNase levels in mutant kernels after 20 DAP could result in mRNA destabilization. The results imply that the qualitative and quantitative patterns of zeins in maize kernels are substantially determined by the differential stability of their mRNAs.