低温对2种玉兰花色及相关酶活性的影响

以4年生紫玉兰和二乔玉兰盛花期外层花瓣为试材,设置温度梯度为-1,-2,-3,-4,-5,-6℃,以自然植株的花瓣作为对照(CK),研究低温胁迫对2种玉兰花色参数L*,a*,6*,C*,花色苷和类黄酮含量以及苯丙氨酸解氨酶(PAL)和查尔酮异构酶(CHI)活性的影响.结果表明:随着处理温度的降低,2种玉兰花瓣的明度L*值降低,色相a*值不断减小,色相6*值升高,紫玉兰C*不断降低,二乔玉兰C*先上升后下降.紫玉兰花色苷和类黄酮含量随着温度的降低而不断降低,PAL和CHI活性逐渐上升；低温胁迫初期,二乔玉兰在花色苷和总黄酮含量变化缓慢,-5℃开始大幅度降低,PAL和CHI活性随着温度的降低呈现缓慢下降的趋势.相关性分析表明:低温处理后二乔玉兰花色苷和类黄酮含量变化与PAL和CHI活性呈显著正相关,而紫玉兰花色苷和类黄酮含量变化与PAL和CHI活性呈负相关.综上所述,低温导致花色苷和类黄酮含量合成受阻,相关酶活性紊乱,严重影响2种玉兰花色的正常表达.

Effect of Low Temperature on Flower Color and Relevant Enzymes Activity of Two Magnolia Species

Outer petals of four-year-old Magnolia liliflora and M. × soulangeana were used to study the floral color parameters,pigment content,PAL and CHI activity under cold stress. The treatment temperature gradients were set as - 1, - 2, - 3, - 4, - 5 and - 6 ℃ ,taking natural plant petals served as controls. The results were as follows: as the temperature decreases,the lightness L * -value and chromatic component a * -value decreased,chromatic component b * - value increased. The C * -value of M. liliflora gradually decrease while M. soulangeana first increase then decrease. The anthocyanin and flavonoid content of M. liliflora decreased,while the PAL and CHI activity increased under the low temperature stress. The anthocyanin and flavonoid content of M. × soulangeana changed slowly at the early stage of low temperature stress,and significantly decreased under - 5 ℃ and lower temperature. The PAL and CHI activity slowly decreased with decreasing temperature. Correlation analysis showed that the anthocyanin and flavonoid content of M. × soulangeana had a significantly positive correlation with PAL and CHI,while those of M. liliflora was negative correlations with PAL and CHI. In summary,low temperature stress was a hinder to the synthesis of anthocyanin and flavonoid, disordered the activity of relevant enzymes and seriously affected the normal color expression of the 2 Magnolia species.