转甜菜碱醛脱氢酶基因马铃薯的抗旱耐盐性

Drought and Salinity Tolerance in Transgenic Potato Expressing the Betaine Aldehyde Dehydrogenase Gene

通过根癌农杆菌介导法将甜菜碱醛脱氢酶(BADH)基因导入马铃薯栽培品种甘农薯2号,经PCR、Southern和Northern杂交证明BADH基因已整合到马铃薯基因组中并在转基因植株中转录和表达。测定表明对照植株没有BADH酶活性,各转化株系在胁迫前后BADH酶活性近似,在2.1～10.5U之间。BADH酶活性与叶片的相对电导率呈一定的负相关(y=–3.774x+57.083,r=0.989**)。在NaCl和PEG胁迫下,转基因植株生长正常,株高比对照提高0.41～1.00cm,单株重量比对照增加10%～35%,说明外源BADH基因的导入提高了马铃薯植株对干旱和盐碱的抗性。

Glycine betaine （GB） is a common compatible solute in many different organisms including higher plants. Many plant species can accumulate GB in response to drought and salinity. GB is synthesized by conversion of choline to GB through a two-step oxidation via the intermadiate betaine aldehyde. In higher plants, the relevant enzymes are choline monooxygenase （CMO） and betaine aldehyde dehydrogenase （BADH）. The fact that many important crops, such as rice, potato and tomato, are betaine-deficient has inevitably led to the proposal that it might be possible to increase drought and salinity tolerances by genetic engineering of GB synthesis. In the present study, the transgenic plants of potato cultivar Gannongshu 2 were obtained by Agrobacterium-mediated transformation of the expression vector pBIBB contained BADH gene under the control of the constitutive promoter CaMV 35S. PCR, Southern and Northern blot analyses showed that the BADH gene was integrated into potato genome, transcribed and expressed in the transgenic plants. The analysis of BADH activity of transgenic plant leaves revealed that the BADH activity ranged from 2 to 11 U, while it was not detectable in the control plants. There was a negative relationship （y= –3.7738x＋57.083, r=0.989^＊＊） between BADH activity and relative electric conductivity of the transgenic potato leaves. The transgenic potato plants grew normally under NaCl and polyethylene glycol （PEG） stresses with increase of 0.4–0.9 cm for plant height and 17–29% for fresh weight per plant compared with the control plants. This result demonstrated that the transgenic potato plants can improve tolerances to drought and salinity as a result of transformation and expression of BADH gene.