A stable isotope labelling assisted LC-MS method for the determination of polyamines in micro-tissues of rice†
A stable isotope labelling assisted LC-MS method was developed for highly sensitive quantitation of polyamines in roots and leaves of rice plants under cadmium stress. Successful quantitation of polyamines in minute amounts of plant extracts allowed the detection of spatial and temporal changes in an organ/tissue-specific manner. Accumulations of putrescine under cadmium stress were observed in the tips of both roots and leaves. However, different regulations of spermine contents in the two regions were observed. Meanwhile, the influence of cadmium stress from the medium was found to be persistent towards the growth of roots after cultivation for 6 days, whereas the leaves gradually reached homeostasis after 3 days. Moreover, our micro-regional analysis on leaf tissues has for the first time revealed that the influences of cadmium stress towards the contents of polyamines gradually translocated directionally on the leaves. Typically, the influences towards the contents of major polyamines shifted from the sheath and central zone towards the tip and peripheral zone.