Expression of MaMAPK Gene in Seedlings of Malus L.under Water Stress  

作　　者：Li-Xin PENG Ling-Kun GU Cheng-Chao ZHENG De-Quan LI Huai-Rui SHU 

机构地区：[1]Department of Horticulture, Tianjin Agricultural College, Tianjin 300384, China [2]College of Life Science, Shandong Agricultural University, Tai'an 271018, China

出　　处：《Acta Biochimica et Biophysica Sinica》2006年第4期281-286,共6页生物化学与生物物理学报（英文版）

基　　金：This work was supported by the grants from the National Nature Science Foundation of China (No.39870526);the National Emphasis Basic Research Item (No.G1999011700)

摘　　要：Seedlings of three species of Malus were used to study the expression of mitogen-activated protein kinase （MAPK） in response to water stress： Malus hupehensis, a drought-sensitive species; Malus sieversii, a drought-tolerant species; and Malus micromalus, a middle type. Results showed that Malus MAPK （MaMAPK, GenBank accession No. AF435805） was expressed in both roots and leaves of seedlings of the three Malus species treated with 20% polyethylene glycol for different time periods. Expression levels peaked at 1.5 h after treatment with polyethylene glycol, then decreased to their lowest levels. Liquid kinase assays indicated that the dynamic changes of MAPK activity were very similar to those of the relative expression of MaMAPK mRNA. However, the peak of the former occurred slightly behind the latter. It was noticed that, although the kinase activity decreased after the peak, it was still higher than that of the control during the whole time period. These results suggested that MaMAPK was regulated not only by water stress at the transcription level, but also by phosphorylation and dephosphorylation at the protein level. In addition, of these three apple species, the highest MAPK activity and MaMAPK expression level was found in M. sieversii, followed by M. micromalus and M. hupehensis, suggesting that MAPK might be correlated with drought tolerance in these three species. The different expression levels might be one of the molecular mechanisms of the different drought tolerances in Malus.Seedlings of three species of Malus were used to study the expression of mitogen-activated protein kinase （MAPK） in response to water stress： Malus hupehensis, a drought-sensitive species; Malus sieversii, a drought-tolerant species; and Malus micromalus, a middle type. Results showed that Malus MAPK （MaMAPK, GenBank accession No. AF435805） was expressed in both roots and leaves of seedlings of the three Malus species treated with 20% polyethylene glycol for different time periods. Expression levels peaked at 1.5 h after treatment with polyethylene glycol, then decreased to their lowest levels. Liquid kinase assays indicated that the dynamic changes of MAPK activity were very similar to those of the relative expression of MaMAPK mRNA. However, the peak of the former occurred slightly behind the latter. It was noticed that, although the kinase activity decreased after the peak, it was still higher than that of the control during the whole time period. These results suggested that MaMAPK was regulated not only by water stress at the transcription level, but also by phosphorylation and dephosphorylation at the protein level. In addition, of these three apple species, the highest MAPK activity and MaMAPK expression level was found in M. sieversii, followed by M. micromalus and M. hupehensis, suggesting that MAPK might be correlated with drought tolerance in these three species. The different expression levels might be one of the molecular mechanisms of the different drought tolerances in Malus.

关 键 词：expression characteristics Malus L. MaMAPK gene water stress 

分 类 号：Q5[生物学—生物化学]