I talked to an Agilent agent and he told, unfortunately there is no assay to correctly tell the RIN values for leafy tissues of plants and that cannot be amended even using plant specific RNA analysis setting. There are two issues with plant, he told. First, plant rRNA gives different peaks than mammalian rRNA. Second, the choloroplast rRNA peaks are recognized as degradation products in the analysis and hence give lower RIN value. But using plant setting in analysis will help in checking rRNA from non-green tissues and can differentiate it from non-plant samples. Having said that, three of my samples are OK and the other three (wild type) are little lower. I suppose, they have lower RIN value as the tissues were more green in comparison to the mutants and might have more chloroplast rRNA. If you see the small peaks next to the 18S/28S peaks, they are much sharper in case of wild type in comparison to the mutants. Those are probably form the chloroplastic rRNA, unfortunately cannot be assayed by Agilent machine. Any suggestions?

We dont work plants so please take note of that all my knowledge comes from eucaryotic and bacterias. My experience is that RIN isn't the only important factor. A high RIN value helps but it's not the only deciding factor. If you have a realatively high RIN value and large amounts of RNA that tends to work better then higher RIN and lower amounts. Fat tissue works poorly while muscle and liver are excellent tissues to work with.

So from your data I'd say that if you have the recommended amounts then it will most likely work. We've used samples with RIN around 5 and they have worked without problems.