Expression Characteristics of AaHsp90 Gene in Antheraea assamensis under Different Temperature and Starvation Stress

[Objectives]To investigate the effects of different temperature and starvation stress on the expression of AaHsp90 and reveal the molecular mechanism of adaptation to environment in Antheraea assama.[Methods]Taking the normal feeding group at 26℃as the control,the expression change of AaHsp90 was detected by real-time PCR in midgut,fat body and hemlymph after high temperature stress at 38℃,low temperature stress at 4℃and starvation stress separately for different time on the third day of the fifth larvae.[Results]The expression of AaHsp90 in midgut,fat body and hemlymph of Antheraea assama were increased obviously at first and then decreased sharply with the prolongation of treatment time at 38℃.There has a certain inhibitory effect on the expression of AaHsp90 in midgut,fat body and hemolymph after treatment with 4℃for different time.After treatment with starvation,the AaHsp90 expression were increased at 12 and 18 h and decreased sharply at 24 h in midgut,fat body and hemolymph of A.assama.[Conclusions]Comprehensive analysis showed that high temperature and starvation stress can induce the expression of AaHsp90,while low temperature stress mainly suppressed its expression.It was suggested that the AaHsp90 protein may play an important role in the process of adaptation to high temperature and starvation stress in A.assama.

Drought-induced proline is mainly synthesized in leaves and transported to roots in watermelon under water deficit

Proline accumulation has been shown to occur in plants in response to various environmental stresses.Although proline metabolismrelated genes have been functionally characterized,the inter-organ transport of proline in stressed plants remains unclear.In this study,free proline was detected with significant accumulations in the roots,stems,and leaves of watermelon drought-tolerant germplasm M08 and drought-susceptible line Y34 under drought stress.Expression profiling and enzyme activity measurements revealed that ClP5CS1 gene,rather than its paralog ClP5CS2,mainly contributes to the proline synthesis in leaves via the Glu pathway.Additionally,over-expression of the ClP5CS genes significantly enhanced the drought tolerance of transgenic Arabidopsis lines.Furthermore,we confirmed that proline is mainly synthesized in leaves and transported to roots in watermelon under drought stress.Transcriptome and expression analyses revealed that the genes involved in proline metabolism exhibited different expression levels.Specifically,ClP5CS1 was upregulated in leaves and roots,while ClP5CS2 was downregulated under drought stress.Also,415 and 362 differently expressed TFs were identified in roots and leaves,respectively,with the majority upregulated in the former.Ultimately,a model for proline metabolism was proposed.The findings of this study provided new insights into the biosynthesis,transport,and regulatory mechanism of drought-induced proline in plants.