Overexpression of Small Heat Shock Protein LimHSP16.45 in Arabidopsis hsp17.6II Mutant Enhances Tolerance to Abiotic Stresses

Abstract

Organisms can produce heat shock proteins (HSPs) in response to elevated temperatures and other abiotic stresses. However, the function of HSPs, including small heat shock proteins (sHSPs), in stress tolerance is not fully explored. To improve our understanding of sHSPs, we isolated a gene of sHSPs from David lily (Lilium davidii Duchartre) called LimHSP16.45. Results reveal that LimHSP16.45 is a cytosolic class II sHSP. The HSP17.6II of Arabidopsis thaliana belongs to the HSP20 chaperone protein and is similar to Lim16.45HSP of David lily in terms of size and structure. Both genes have a small heat shock-like alpha-crystallin domain (ACD) structure. To further study the function of Lim16.45HSP, we overexpress it in Arabidopsis hsp17.6II mutant. Then, we detect the expression of LimHSP16.45 in transgenic plant under abiotic stresses and analyze the heat tolerance of transgenic plant. In addition, we measure the activity of three antioxidant enzymes (peroxidase, catalase and superoxide dismutase) and the content of soluble sugar and proline in transgenic plants under abiotic stresses.We found that transgenic plant is tolerant to heat and oxidative stresses given its increased survival rate relative to the hsp17.6II and wild type. Moreover, the content of soluble sugar and proline considerably increase in the transgenic plant. These results support the positive role of LimHSP16.45 in response to heat stress in plants. We suspect that LimHSP16.45 enhances plant tolerance to abiotic stresses by stimulating the activity of ROS-scavenging enzymes and other protective enzymes and increasing the synthesis of proline.