2种茄科植物花色变化的生理生化机制

Physiological and Biochemical Mechanisms of Flower Color Change in Two Plants of Solanaceae Family

为探究鸳鸯茉莉与大花茄2种茄科植物花色变化的机制,为植物花色育种提供理论依据,对鸳鸯茉莉与大花茄开花进程中6个阶段的花色表型,pH值,可溶性糖、可溶性蛋白、花色苷、类黄酮、类胡萝卜素含量,苯丙氨酸解氨酶(PAL)、查尔酮异构酶(CHI)活性等相关生理生化指标进行了测定和比较,并对花色苷组分进行定性和定量分析。结果显示,鸳鸯茉莉与大花茄开花进程中花瓣中的可溶性糖含量、可溶性蛋白含量、CHI活性、花色苷含量均表现为先上升后下降的变化趋势,但二者pH值、PAL活性、类胡萝卜素含量、类黄酮含量变化趋势不同。开花进程中鸳鸯茉莉花瓣中类黄酮含量(初花期除外)和花色苷含量(盛花末期和末花期除外)均高于大花茄,且均于花蕾末期达到峰值。2种植物的花色苷提取液均检测出6种色谱组分,大花茄花瓣中组分a2定性为氯化矢车菊素,组分a3定性为氯化矮牵牛素,而鸳鸯茉莉花瓣中组分b4定性为氯化矮牵牛素,其余组分还需进一步确定。相关性分析表明,鸳鸯茉莉开花进程中各色度值指标均与花色苷含量呈极显著相关关系,与类黄酮含量的相关性不显著;大花茄开花进程中色度值指标L*、a*、b*、C*与花色苷含量和类黄酮含量均呈极显著相关关系。可见,鸳鸯茉莉花色主要与花色苷含量有关,花色变化是花色苷含量下降所致,在蕾期合成积累的花色苷随着花朵开放,在阳光强烈照射下,稳定性受到影响,部分花色苷发生了降解,导致花色变白;而大花茄花色由花色苷与类黄酮含量共同控制,花色的变化除了与总花色苷含量下降有关外,还与花色苷组分比例变化有关。

By way of measuring the flower color phenotype,the pH value,the content of soluble sugar and soluble protein,the enzymatic activity of PAL(phenylalanine ammonia‑lyase)and CHI(halcone isomerase),the content of anthocyanin,flavonoid and carotenoid in six flowering phases of Brunfelsia acuminata and Solanum wrightii,this study explored their color changing mechanism,to provide a theoretical basis for flower color breeding.Results showed that Brunfelsia acuminata and Solanum wrightii displayed similar change trend of increasing first and then decreasing in the content of soluble sugar and soluble protein,the enzymatic activity of CHI,the content of anthocyanin during flowering,while displayed different change trends in the pH value,the enzymatic activity of PAL,the content of flavonoid and carotenoid.The contents of flavonoid(except initial flowering phase)and anthocyanin(except late full‑bloom phase and end of the flowing phase)of Brunfelsia acuminata were higher than those of Solanum wrightii,and all reached the peak value in the late flower bud phase.Six chromatographic components were detected in the anthocyanin extract of both plants.The a2 and a3 components of Solanum wrightii were identified as cyanidin chloride and petunia chloride,and the b4 component of Brunfelsia acuminate was identified as petunia chloride,and the rest components needed to be further determined.The correlation analysis showed that the chromaticity value indexes(L*,a*,b*,C*and h)were significantly correlated with the content of anthocyanin during flowering process in Brunfelsia acuminata,but not with the content of flavonoid.The chromaticity indexes L*,a*,b*,and C*were significantly correlated with the content of anthocyanin and flavonoid during flowering process in Solanum wrightii.The results indicated that the flower color of Brunfelsia acuminata was connected with the content of anthocyanin,and the flower color change was caused by the decline of anthocyanin content.Some anthocyanin which was synthesized and accumulated during the bud stage degraded under the intense sunlight,resulting in the color fading.However,the flower color of Solanum wrightii was controlled by the content of anthocyanin and flavonoid,the flower color change was not only related to the decline of anthocyanin content,but also to the proportion changes of anthocyanin components.