外源褪黑素对小麦幼苗生理及光合荧光特性的影响

Effects of exogenous melatonin on physiological and photosynthetic characteristics of wheat seedings

关键词:  褪黑素, 小麦, 叶绿素, 叶绿素荧光, 光合特性, 生理

Key words:  melatonin, wheat, chlorophyll, chlorophyll fluorescence, photosynthetic characteristics, physiology

摘要:

为探讨不同浓度外源褪黑素对小麦幼苗生理及光合荧光特性的影响,该研究以良星99为供试材料,测定不同浓度褪黑素处理下小麦幼苗生长形态、光合及荧光参数以及抗氧化酶活性等关键指标。结果表明:(1)0.1 μmol·L^-1的褪黑素处理显著提高了小麦植株的光合能力,叶绿素Chl a、Chl b和Chl(a+b)以及叶绿素荧光参数调节性能量耗散的量子产额Y(NPQ)、表观光合传递速率(ETR)和非光化学淬灭(NPQ)均在褪黑素浓度为0.1 μmol·L^-1时达到增加最大值; PSⅡ最大光合效率(Fv/Fm)、最大光能转化潜力(Fv/Fo)随褪黑素浓度升高逐渐降低; 光化学淬灭(qL)随褪黑素浓度增加先下降后上升。(2)与CK(0 μmol·L^-1)相比,低浓度褪黑素显著降低小麦根和叶中过氧化物酶(POD)及小麦叶中过氧化氢酶(CAT)的活性,高浓度褪黑素处理显著增加小麦POD的活性; 小麦根中丙二醛(MDA)含量随褪黑素浓度的增加先下降后上升。综上表明,适量褪黑素处理可促进小麦的生长,使小麦光合能力维持在较高水平,并通过POD和CAT调节不同褪黑素处理引起的氧化应激。该研究为进一步了解褪黑素在小麦中的调控作用机制奠定了基础。

Abstract:

To explore the effects of different concentrations of melatonin on physiological and photosynthetic fluorescence characteristics of wheat seedlings. The growth morphology, photosynthetic, fluorescence parameters and antioxidant enzyme activity of wheat seedings treated with different concentrations of melatonin were determined by using Liangxing 99 as experimental material. The results were as follows:(1)0.1 μmol·L^-1 melatonin treatment significantly increased the photosynthetic capacity of wheat plants, Chlorophyll a(Chl a), Chlorophyll b(Chl b)and Chlorophyll(a+b)[Chl(a+b)] increased to the maximum value when melatonin concentration was 0.1 μmol·L^-1. Chlorophyll fluorescence parameters include parameters of quantum yield of regulated energy dissipation Y(NPQ), the electron transport rate(ETR)and non-photochemical quenching(NPQ)also reached the maximum at 0.1 μmol·L^-1. The PS Ⅱ maximum photosynthetic efficiency(Fv/Fm)and maximum photochemical conversion potential(Fv/Fo)decreased with the increase of melatonin concentration. Photochemical quenching(qL)decreased first and then increased with the increase of melatonin.(2)Compared with CK(0 μmol·L^-1), low concentration of melatonin treatment significantly decreased peroxidase(POD)activity in wheat and decreased catalase(CAT)activity in wheat leaves, high melatonin concentration significantly increased POD activity in wheat. The content of malondialdehyde(MDA)in wheat roots decreased firstly and then increased with the increase of melatonin concentration. In conclusion, it suggests that appropriate melatonin treatment can promote the growth of wheat and maintain the photosynthetic capacity of wheat at a high level, and can also regulate oxidative stress induced by different concentrations of melatonin in wheat seedlings through POD and CAT. This study laid a foundation for further understanding the regulatory mechanism of melatonin in wheat.