铝胁迫对烟草叶片光能利用、光保护系统及活性氧代谢的影响

摘要

In order to reveal the mechanism of tobacco leaf light energy utilization and photoprotective systems in aluminum (Al)-induced reactive oxygen species metabolism,two different Al-tolerant tobacco cultivars Yunyan 100 (Al-tolerant) and Yunyan 105 (Al-sensitive) were used to study effects of four Al concentrations (0,50,100,200 μmol/L) on plant growth,reactive oxygen content,photosynthesis,chlorophyll fluorescence characteristics,photorespiration,activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in leaves of tobacco cultivar with solution culture method.The results showed that increasing Al concentrations significantly decreased the leaf chlorophyll content,net photosynthetic rate (Pn),maximal photochemical efficiency (Fv/Fm),quantum yield of electron transport at PS Ⅱ (φPS Ⅱ) and coefficient of photochemical quenching (qP),increased ex cess energy of PS Ⅱ photochemistry leading to higher accumulation of leaf O2 and H2O2,and lower plant biomass,especially in Yunyan 105.With the Al concentrations increased from 0 to 200 μmol/L,the coefficient of non-photochemical quenching (NPQ),photorespiration rate,and activities of SOD and APX were promoted firstly and then reduced again.Compared with Al-sensitive cv.Yunyan 105,Al-tolerant cv.Yunyan 100 remained higher leaf φPSⅡ,qP,NPQ,photorespiration rate,and activities of SOD and APX under different Al concentrations.These results indicated that tobacco could enhance the tolerance to Al stress by increasing photochemical reaction capacity,heat dissipation,photorespiration and activities of antioxidative enzymes in order to decrease excess energy of PS Ⅱ photochem istry,which prevents or eliminates reactive oxygen accumulation under the low Al concentration.%为了揭示烟草叶片光能利用和光保护系统在铝诱导的活性氧代谢中的作用机理,以2个不同耐铝性的烟草品种云烟100(耐铝)和云烟105(敏感)为材料,采用水培法研究了不同铝浓度(0,50,100,200 μmol/L)对烟草植株生长、叶片活性氧含量、光合特性、叶绿素荧光参数、光呼吸、超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性的影响.结果表明,铝浓度的升高显著降低了烟草叶片叶绿素含量、净光合速率(Pn)、最大光化学效率(Fv/Fm)、PSⅡ光合电子传递量子效率(中PSⅡ)和光化学猝灭系数(qP),提高了反应中心PSⅡ过剩激发能,从而导致叶片O2和H2O2含量升高,植株生物量下降,其中对云烟105影响大于云烟100.随铝处理浓度的升高,烟草叶片非光化学猝灭系数(NPQ)、光呼吸速率、SOD和APX活性呈先升后降的趋势.与敏感品种云烟105相比,耐铝品种云烟100在不同铝浓度胁迫下表现出更高的φPSⅡ、qP、NPQ、光呼吸速率以及SOD和APX活性,说明低浓度铝胁迫下烟草叶片可通过提高光化学反应能力、热耗散、光呼吸以及抗氧化酶活性等途径来降低反应中心PSⅡ过剩激发能,防止或清除活性氧的积累,从而增强其对铝的耐性.