多倍化对青钱柳叶形态、光合性能和次生代谢产物积累的影响

Effects of Polyploidization on Leaf Morphology,Photosynthetic Performance and Accumulation of Secondary Metabolites in Cyclocarya paliurus

【目的】比较分析青钱柳二倍体和四倍体的叶形态、光合性能和次生代谢物积累的差异,以期为青钱柳叶用林良种选育提供理论参考。【方法】以鹤峰和清凉峰2个种源的成年植株为试验材料,分别测定二倍体和四倍体的叶形态指标、解剖结构、气孔参数,比较光合生理的相关参数,监测叶次生代谢产物含量的季节动态及差异。【结果】1)四倍体叶长、叶宽、叶面积分别为10.94 cm、4.57 cm、118.84 cm^(2),比二倍体分别高出19.5%、61.4%、94.2%,而比叶质量无显著差异;四倍体叶解剖结构各部分、气孔形态均显著大于二倍体,气孔密度为158.36个·mm^(−2),比二倍体少43.8%。2)四倍体叶类胡萝卜素含量显著高于二倍体,叶绿素a、叶绿素b无显著差异;通过对光响应曲线拟合得到二倍体和四倍体的最大净光合速率(Pnmax)、暗呼吸速率(Rd)、光补偿点(LCP)、光饱和点(LSP)分别为8.367、0.997、25.905、1527.96μmol·m^(−2)s^(−1)和13.797、1.573、32.905、1311.36μmol·m^(−2)s^(−1);瞬时光合测定发现四倍体净光合速率、胞间CO_(2)、蒸腾速率均显著大于二倍体;气孔导度、蒸气压亏缺则差异不显著。3)二种倍性植株叶内主要活性物质的积累高峰均出现在5月和9月;三萜化合物和黄酮含量在主要的收获季节(5月和9月)倍性间均无显著差异;四倍体多酚含量(13.64 mg·g^(−1))仅于5月显著高于二倍体(13.29 mg·g^(−1)),但四倍体多糖含量在整个生长季节均显著高于二倍体,5月和9月的含量分别达6.80和8.58 mg·g^(−1)。【结论】青钱柳四倍体叶形态、叶解剖结构和光合生理特性均显著优于二倍体,促进了四倍体叶生物量积累;四倍体在5月份的多酚含量和叶多糖含量全生长季显著高于二倍体,黄酮、三萜含量倍性间在主要的收获季节均无显著差异。综合评价认为,四倍体是低海拔地区叶用青钱柳人工林生产的主要栽培材料,可获得更高的生物活性物质产量。

【Objective】Cyclocarya paliurus is a unique medicinal plant in China,and its diploid and autotetraploid individuals coexist in natural populations.This study aims to compare and analyze the differences in leaf morphology,photosynthetic performance and secondary metabolite accumulation between diploidy and tetraploidy,in order to provide a basis for elite genotype selection for leaf-use plantations.【Method】The leaf morphology,anatomical structure,and stomatal parameters in diploid and tetraploid adult plants from Hefeng,Hubei Province and Qingliangfeng,Anhui Province were measured.Their photosynthetic physiological parameters were also determined.The seasonal dynamics and differences of secondary metabolite profiles between two ploidies were compared.【Result】1)The length,width,and area of tetraploid leaves were 10.94 cm,4.57 cm,and 118.84 cm^(2),respectively,which were 19.5%,61.4%,and 94.2%greater than those of diploid leaves.However,there was no significant difference in specific leaf mass.In similar,various tissues in leaf anatomical structure and stomatal morphology in tetraploidy were also significantly larger than that in diploidy.However,the stomatal density in tetraploidy was 158.36 stomata·mm^(−2),which was 43.8%less than that of diploidy.2)The carotenoid content in tetraploidy was significantly higher than that in diploidy,and there were no significant differences in chlorophyll a and chlorophyll b between the two ploidies.The parameters obtained from fitted curves of light response showed that maximum net photosynthetic rate(Pnmax),dark respiration rate(Rd),light compensation point(LCP),and light saturation point(LSP)in diploid were 8.367,0.997,25.905,and 1527.96μmol·m^(−2)s^(−1),while were 13.797,1.573,32.905,and 1311.36μmol·m^(−2)s^(−1)in tetraploidy,respectively.Measurement for instantaneous photosynthesis revealed that net photosynthetic rate,intercellular CO_(2)concentration,and transpiration rate in tetraploidy were significantly higher than those in diploidy.There were no significant differences in stomatal conductance and vapor pressure deficit.3)The accumulation peaks of major bioactive substances in leaves of two ploidies all occurred in May and September,respectively.There were no significant differences in the content of triterpenoids and flavonoids in two harvest seasons(May and September)between ploidies.The polyphenol content of tetraploidy(13.64 mg·g^(−1))was significantly higher than that of diploidy(13.29 mg·g^(−1))only in May,while the polysaccharide content of tetraploidy remained consistently higher than that of diploidy throughout the entire growing season,reaching 6.80 mg·g^(−1)and 8.58 mg·g^(−1)in May and September,respectively.【Conclusion】The leaf morphology,anatomical structure and photosynthetic physiological characteristics in tetraploidy are significantly better than those of diploidy,thus promoting its leaf biomass production.The polyphenol content in May and polysaccharide content in whole growth seasons in tetraploidy are significantly higher than those in diploidy,but there is no significant difference in flavonoids and triterpenes contents in the main harvest seasons between two ploides.Comprehensively,the tetraploid is the candidate material for leaf-use plantations in low-altitude areas,and can obtain higher yields of bioactive substances in practice.