VARIATIONS OF PROXIMAL COMPOSITION IN PILEA MICROPHYLLA (L.) LIEBM DUE TO DESICCATION AND REHYDRATION IMPACTS

Abstract

Water deficiency is the most significant abiotic stress factor for land plants. Most plants are unable to survive desiccation to the air dry state. There are however a few species from lower plant groups to flowering plants that tolerate desiccation known as resurrection plants. So, the present investigation was undertaken to
study the biochemical changes in Pileamicrophylla against desiccation (1, 3, 5 and 7 days) and rehydration (30 min) stress. As an initial part of the study total sugar, protein and proline content were analyzed and showed a gradual decline during the stress periods. The SDS-PAGE analysis of protein indicated the
disapperance of certain bands in the desiccated and rehydrated samples (7D) when compared to the control indicating the denaturation of proteins during stress. Similarly, the appearance of new bands (15kDa on 3D and 20 and 17kDa on the 5D) were noticed suggesting the formation of stress related proteins to tide over desiccation. The amount of free amino acids increased in P. microphylla, in pace with desiccation periods. Constitutive increase in the level of proline (the stress amino acid) accumulation is seen when compared with the control i.e., 6 fold higher than that of the control, after exposed to desiccation for 5 D. Increase in proline level relating to exposure time of desiccation stress suggests its role as osmolyte. Similarly, a reduction in chlorophyll level and an increase in carotenoid were also observed during stress. Decrease of total chlorophyll content was observed with duration of desiccation. The decrease in chlorophyll a and b was recovered during rehydration up to 5 D. Further studies are warranted at molecular level in terms of stress proteins and genes involved in desiccation tolerance in this plant.