Both C. flavum and P. armeniacum, known as lady's slipper orchids, are endemic to China. Paphiopedilum and Cypripedium are close relatives in the subfamily Cypripedioideae. Cypripedium leaves contain guard cell chloroplasts, whereas Paphiopedilum do not. It is unclear whether the lack of guard cell chloroplasts affects photosynthetic induction, which is important for understory plants to utilize sunflecks.
With an aim to understand the role of guard cell chloroplasts in photosynthetic induction of Paphiopedilum and Cypripedium, Dr. Zhang Shibao of XTBG and his colleagues investigated the stomatal anatomy and photosynthetic induction of Paphiopedilum armeniacum and Cypripedium flavumat different ratios of red to blue light.
The research found that the photosynthetic induction and performance in P. armeniacum were significantly different from those of C. flavum. The slow photosynthetic induction and low photosynthetic rate in P. armeniacum were linked to the lack of guard cell chloroplasts and specific stomatal structure, which reflected an adaption to low soil water availability.
The research resultsprovided evidence for the morphological and physiological evolution of stomata relating to water-conserving traits under natural selection.