Studies On Heat Shock Proteins (HSPs) Of Rice (Oryza Sativa L.) In Response To Heat Stress

The overall global temperature has steadily increased in recent decades due to rapid increases in atmospheric greenhouse gas concentrations. Rice production is likely to be affected severely by an increase in mean global temperature. Meanwhile, the inherent immobility of rice plants limits their abilities to avoid stress, requiring them to treat with heat stress through innate defense mechanisms, in which heat shock proteins (HSPs) may play important roles.In this study, three rice cultivars (Oryza sativa L.), Nipponbare, Azucena (susceptible to heat) and Co39 (tolerant to heat), with different ability to avoiding heat stress, were used as materials. The experiment was conducted to study the differential expression and interaction of sHSP in rice in response to high temperature stress. The result are as following:1. By using the 2-DE and RT-PCR, five sHSPs, HSP26.7, HSP23.2, HSP17.9A, HSP17.4 and HSP16.9A, in the leaves of 3 rice cultivars were found to be up-regulated in response to heat stress. The expressing abundances of the 5 sHSP in Co39 were all significantly higher than that in Azucena. The same were ture in the root of Nipponbare under heat stress. The expressing abundance of theses 5 sHSPs were also up-regulated in the leaves of Nipponbare during anthesis under heat stress. These findings were validated by the RT-PCR assay. The result indicated that these 5 sHSPs were involved in the defense system of rice in response to heat stress. Meanwhile, their expressing abundances could be used as markers to assess the ability of avoiding heat stress in rice cultivars.2. By using 2-D Native/SDS-PAGE to separate the protein complexs, HSPs were found to be involved in four protein complexes, which were named complex 1 (C1), complex 2 (C2), complex 3 (C3) and complex 4 (C4), respectivelty. In C1, there were four sHSPs, inculding HSP18.1, HSP17.9A, HSP17.7 and HSP16.9A, which was identified by Yeast Two-Hybridization analysis. OSJNBa0027H06.1, Methylmalonate semi-aldehyde dehydroge- nase and GS participated in C3, resulting the increase of GS acitivity. The result from the exp- eriment of His-Pull down showed that ten proteins mainly responsing for glycolysis and ATP synthesis interacted with HSP16.9, suggesting that C1 complex minght be involved in intracellular energy metabolism.The result in this study revealed the expression and network of sHSP in rice in response to heat stress, which would facilitate the development of heat-tolerant cultivars with improved productivity in a warm future climate.