Theses and Dissertations

Issuing Body

Mississippi State University


Li, Jiaxu

Committee Member

Ma, Din-Pow

Committee Member

Shan, Xueyan

Date of Degree


Document Type

Graduate Thesis - Open Access



Degree Name

Master of Science


College of Agriculture and Life Sciences


Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology


Stomata are small pores that are located on the surface of epidermal leaves, and they can regulate the uptake of CO2 and prevent water lose by opening and closing the pores. Stomata of plants can be regulated by external condition such as CO2, biotic and abiotic stresses and internal factors. CAM (crassulacean acid metabolism) plants adapt to hot and dry environments by closing stomata during the day and opening stomata during the cool night. However, it is still unclear how CAM plants open their stomata during the night and close them during the day. In this study, a number of factors were evaluated for their potential roles in promoting stomatal opening in the model CAM plant Kalanchoe laxiflora. Citrate is an important organic acid and it accumulates during the night in CAM plants. It is shown in this study that citrate promoted stomatal opening in detached leaf epidermis of Kalanchoe laxiflora. Further, the cytokinin zeatin is also shown to stimulate stomatal opening in detached leave of Kalanchoe laxiflora. Melatonin is an important regulator of circadian rhythms in mammals and has been implicated in regulation of plant abiotic stress responses. Melatonin was detected in the leaves of Kalanchoe laxiflora. It promoted stomatal opening in detached epidermis of Kalanchoe laxiflora. Together, these results suggest that stomata of Kalanchoe laxiflora respond to citrate and malate which are the main organic acids accumulate during nighttime and also to some signaling molecules (zeatin, melatonin, and serotonin) by opening stomata during dark period.



malic acid||citric acid||malate dehydrogenase||phosphoenolpyruvate carboxylase||RUBISCO||Native gel electrophoresis||preparation of epidermal strip||Indole Acetic Acid||cytoplasmic NADP-malic enzyme||potassium||measurements of aperture size||vacuole