根施甜菜碱对干旱胁迫下小麦幼苗类囊体膜组分和功能的影响

Effects of Root-applied Glycinebetaine on the Composition and Function of Wheat Thylakoid Membrane Under Drought Stress

干旱胁迫造成两小麦品系类囊体膜上的单半乳糖脂甘油二酯(MGDG)、双半乳糖脂甘油二酯(DGDG)、磷脂酰胆碱(PG)以及叶绿素含量显著下降,甜菜碱预处理能缓解这些组分的下降。干旱胁迫下,抗旱型小麦品系HF9703的硫代异鼠李糖甘油二酯(SQDG)、反式十六碳-烯酸[16:1(3t)]含量显著上升,MGDG中亚麻酸(18:3)相对含量显著下降;而干旱敏感型品系SN215953则表现为SQDG、16:1(3t)含量显著下降,MGDG中脂肪酸变化不明显,这可能是两个小麦品系抗旱性差异的重要原因之一;甜菜碱处理能显著减小干旱处理与对照之间的差异,且对SN215953的作用较HF9703大。另外,干旱胁迫引起类囊体膜上Ca2+-ATPase活性、Hill反应活性及叶片净光合速率下降,外源甜菜碱能缓解其下降趋势。

Two wheat cultivars (Triticum aestivumL.), HF9703 tolerant to drought and SN215953sensitive to drought, were used to study the effectsof glycinebetaine on the composition and functionof thylakoid membrane. The wheat seedlings withtwo leaves were pretreated with Hoagland solutioncontaining 1.5 mmol/L glycinebetaine (GB) for 72 h,then cultured with Hoagland solution containing 15%PEG-6000 for 48 h. The seedling leaves were usedfor mensuration. The results indicated that the chlo-rophyll (Fig.3), monogalactosyl diaylglycerol(MGDG), digalactosyl diacylglycerol (DGDG) andphosphatidylglycerol (PG) contents (Fig.2) of thetwo wheat cultivars decreased significantly (P<0.05)under drought stress. GB alleviated their decrease(Fig.2 and Fig.3). The sulfoquinovosyl diacylglycerol(SQDG) content (Fig.2), trans-hexadecenoic [16:1(3t)] and saturated fatty acid content of MGDG inHF9703 (Table 1) increased significantly (P<0.05),while in SN215953 (Fig.2), the sulfoquinovosyldiacylglycerol (SQDG) and trans-hexadecenoic [16:1(3t)] contents decreased significantly under drought stress, but the saturated fatty acid content of MGDGincreased slightly. These differences between the twowheat cultivars might account for much of the dif-ference in drought tolerance between them. Ca2+-ATPase activity of thylakoid membrane (Fig.4), Hill-reaction activity (Fig.5) and photosynthesis (Fig.6)were decreased markedly (P<0.05) by droughtstress. GB ameliorated these effects on thylakoidmembrane, and the effect of GB on SN215953 wasstronger than on HF9703. Discussion was made onthe possible mechanism of the alleviating effect ofroot-applied GB on the composition and functionof thylakoid membrane.