I am a new memeber to this forum. I am doing PhD in molecular bilogy. My work is to generate transgenic tobacco plants and to analyse the transcript levels of the transgene at different stages of leaf development. For this, I took very young, mature and the very old leaf as senescent leaf. I extracted RNA from all the leaf samples using Trisure. But the problem is that the RNA is getting degraded in the senescent leaf samples and mature leaf samples. Initially I thought it was a problem in handling the material but even the second time extraction remains the same. Hence I am unable to decide the reason for this. I would be very thankful if some one explains me the reason for this - if it is due to handling or in plant cells itself the RNA degrades faster in mature and old leaf samples.