缘管浒苔和浒苔对海水盐度胁迫的生理响应

Physiological responses of Enteromorpha linza and Enteromorpha prolifera to seawater salinity stress

为探讨大型海藻对盐度的生理响应及其适应机制,以缘管浒苔和浒苔为试验材料,研究了不同盐度的稀释或浓缩海水处理10d对浒苔属植物鲜质量(FM)、相对生长速率(RGR)、相对电导率(REC)、叶绿素含量(Chl)、类胡萝卜素含量(Car)、色素比值(Chla/Chlb、Chl/Car)、叶绿素荧光参数和渗透调节能力(OAA)的影响.结果表明:与对照相比,10%～200%海水处理均明显促进两浒苔属品种的FM和RGR,缘管浒苔和浒苔分别在100%和50%海水处理下的FM和RGR达到最大值;300%海水处理显著抑制两浒苔生长,缘管浒苔受抑制程度较大;缘管浒苔的生物量仅在50%、100%海水处理下呈现正增长,浒苔生物量在10%、50%、100%、200%海水处理下均呈现正增长.10%海水处理下,两浒苔的Chl、Car、Chla/Chlb显著上升,且随海水盐度的增加,呈现先增后降,缘管浒苔和浒苔的Chl、Car、Chla/Chlb分别在100%、50%海水处理下达到最大值.随盐度的增加,叶绿素荧光参数PSⅡ最大光能转化效率(Fv/Fm)、PSⅡ实际光能转化效率(Yield)、最大相对电子传递速率(rETRmax)、光能利用效率(α)和半饱和光强(Ik)都显示与Chl相同的变化趋势.10%～300%海水处理下,浒苔属均表现出一定的OAA,缘管浒苔在100%海水处理下,OAA达到最大值,浒苔在50%海水处理下,OAA达到最大值.两浒苔的生长指标除与Chl/Car无明显的相关性,与REC呈极显著负相关,与Chl、Car、Chla/Chlb、Fv/Fm、Yield、rETRmax、α、Ik、OAA呈极显著正相关.100%和50%海水处理分别对缘管浒苔和浒苔的生长最适宜,浒苔生长适应盐度的范围比缘管浒苔宽.REC、Chl、Car、Chla/Chlb、Fv/Fm、Yield、rETRmax、α、Ik和OAA均可以作为浒苔属植物生长盐适应性的评价指标.

To investigate the physiological responses and adaptation mechanisms of Enteromorpha to seawater salinity stress,a laboratory experiment with Enteromorpha linza and E.prolifera was conducted to study their fresh mass（FM）,relative growth rate（RGR）,relative electrical conductivity（REC）,chlorophyll（Chl） and carotenoid（Car） contents,Chl a/Chl b,Chl/Car,chlorophyll fluorescence parameters,and osmotic adjustment ability（OAA） under the stress of different salinity levels of diluted and concentrated seawater for 10 days.Compared with the control,10%-200% salinity seawater increased the FM and RGR of the two Enteromorpha species obviously,100% and 50% salinity seawater made the FM and RGR of E.linza and E.prolifera peaked,respectively,while 300% salinity seawater decreased the FM and RGR of E.linza and E.prolifera significantly,with the decrement being larger for E.linza.The biomass of E.linza and E.prolifer only had an increase in 50% and 100% sanity seawater and in 10%,50%,100%,and 200% salinity seawater,respectively.The Chl and Car contents and Chl a/Chl b of E.linza and E.prolifera had a significant increase in 10% salinity seawater,but decreased after an initial increase with the increasing salinity level of seawater.The Chl and Car contents and Chl a/Chl b of E.linza and E.prolifera peaked in 100% and 50% salinity seawater,respectively.With increasing salinity of seawater,the light use efficiency（α）,maximal photochemical efficiency of PSⅡ（Fv/Fm）,actual photochemical efficiency of PSⅡ in the light（Yield）,maximal relative electron transport rate（rETRmax）,and half-saturation light intensity（Ik） of E.linza and E.prolifera all showed the same variation trend as Chl.10%-300% salinity seawater enabled E.linza and E.prolifera to express certain osmotic adjustment ability（OAA）,and the OAA of E.linza and E.prolifer peaked in 100% and 50% salinity seawater,respectively.The growth of Enteromorpha had no correlation with Chl/Car,but was significantly negatively correlated with REC and positively correlated with Chl,Car,Chl a/Chl b,Fv/Fm,Yield,rETRmax,α,Ik,and OAA.To sum up,100% salinity was the optimal salt concentration for the growth of E.linza,and 50% salinity was optimal for E.prolifera.E.prolifera could adapt to a wider range of salinity than E.linza.The parameters REC,Chl,Car,Chl a/Chl b,Fv/Fm,Yield,rETRmax,α,Ik,and OAA could be used to evaluate the salt adaptation of Enteromorpha.