Yan Juan, Wang Menglin, Zhang Ling
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Divers. 2017 Nov 24;40(1):28-34. doi: 10.1016/j.pld.2017.11.004. eCollection 2018 Feb.
Petal color change, a common phenomenon in angiosperms, is induced by various environmental and endogenous factors. Interestingly, this phenomenon is important for attracting pollinators and further reproductive success. L. (Combretaceae) is a tropical Asian climber that undergoes sequential petal color change from white to pink to red. This color changing process is thought to be a good strategy to attract more pollinators. However, the underlying physiological and biochemical mechanisms driving this petal color change phenomenon is still underexplored. In this context, we investigated whether changes in pH, pollination, light, temperature or ethylene mediate petal color change. We found that the detected changes in petal pH were not significant enough to induce color alterations. Additionally, pollination and temperatures of 20-30 °C did not alter the rate of petal color change; however, flowers did not open when exposed to constant temperatures at 15 °C or 35 °C. Moreover, the application of ethylene inhibitor, i.e., silver thiosulphate, did not prevent color change. It is worth mentioning here that in our study we found light as a strong factor influencing the whole process of petal color change, as petals remained white under dark conditions. Altogether, the present study suggests that petal color change in is induced by light and not by changes in petal pH, pollination, ethylene, or temperature, while extremely low or high temperatures affect flower anthesis. In summary, our findings represent the probable mechanism underlying the phenomenon of petal color change, which is important for understanding flower color evolution.
花瓣颜色变化是被子植物中常见的现象，由各种环境和内源因素诱导。有趣的是，这种现象对于吸引传粉者和进一步实现繁殖成功很重要。使君子（使君子科）是一种亚洲热带攀缘植物，其花瓣颜色会依次从白色变为粉色再变为红色。这种颜色变化过程被认为是吸引更多传粉者的良好策略。然而，驱动这种花瓣颜色变化现象的潜在生理和生化机制仍未得到充分探索。在此背景下，我们研究了pH值变化、授粉、光照、温度或乙烯是否介导花瓣颜色变化。我们发现检测到的花瓣pH值变化不足以显著诱导颜色改变。此外，授粉和20 - 30°C的温度并未改变花瓣颜色变化的速率；然而，当暴露在15°C或35°C的恒温下时，花朵并未开放。此外，施用乙烯抑制剂硫代硫酸银并不能阻止颜色变化。在此值得一提的是，在我们的研究中，我们发现光照是影响花瓣颜色变化全过程的一个重要因素，因为在黑暗条件下花瓣仍保持白色。总之，本研究表明，使君子花瓣颜色变化是由光照诱导的，而非花瓣pH值、授粉、乙烯或温度的变化，而极低或极高的温度会影响花朵开放。综上所述，我们的研究结果揭示了花瓣颜色变化现象背后的可能机制，这对于理解花色进化具有重要意义。
