Luo Yan, Liu Yu Bo, Dong Yu Xiu, Gao Xin-Qi, Zhang Xian Sheng
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, PR China.
J Plant Physiol. 2009 Mar 1;166(4):385-94. doi: 10.1016/j.jplph.2008.06.018. Epub 2008 Oct 16.
Plant helicases are known to be involved in salinity and low-temperature tolerance. However, a functional involvement of helicases in the antioxidative response of plants has not been described. We have isolated a DEAD-box-containing cDNA sequence from Medicago sativa (alfalfa) that is a homolog of the pea DNA helicase 45 (PDH45) and named it M. sativa helicase 1 (MH1). Transient transfection of 35S::MH1-GFP to onion epidermis revealed that MH1 was localized in the nucleus. Expression of MH1 was detected in roots, stems and leaves of alfalfa. Furthermore, real-time PCR analysis revealed that mannitol, NaCl, methyl viologen and abscisic acid induced the expression of MH1. The ectopic expression of MH1 in Arabidopsis improved seed germination and plant growth under drought, salt and oxidative stress. The capacity for osmotic adjustment, superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and proline content were also elevated in the transgenic Arabidopsis plants. Our results suggest that MH1 responds to reactive oxygen species (ROS) and functions in drought and salt stress tolerance by enhancing the capacities for ROS scavenging and osmotic adjustment.
已知植物解旋酶参与盐度和低温耐受性。然而，尚未有关于解旋酶在植物抗氧化反应中的功能参与的描述。我们从紫花苜蓿（苜蓿）中分离出一个含有DEAD盒的cDNA序列，它是豌豆DNA解旋酶45（PDH45）的同源物，并将其命名为紫花苜蓿解旋酶1（MH1）。将35S::MH1-GFP瞬时转染到洋葱表皮显示MH1定位于细胞核。在苜蓿的根、茎和叶中检测到MH1的表达。此外，实时PCR分析表明甘露醇、NaCl、甲基紫精和脱落酸诱导了MH1的表达。MH1在拟南芥中的异位表达改善了干旱、盐和氧化胁迫下的种子萌发和植物生长。转基因拟南芥植株的渗透调节能力、超氧化物歧化酶（SOD）和抗坏血酸过氧化物酶（APX）活性以及脯氨酸含量也有所提高。我们的结果表明，MH1对活性氧（ROS）作出反应，并通过增强ROS清除能力和渗透调节能力在干旱和盐胁迫耐受性中发挥作用。
