H2O2, Ca2+, and K+ in subsidiary cells of maize leaves are involved in regulatory signaling of stomatal movement

Li Zhang,Dongyang Li,Yaqin Yao,Suiqi Zhang

doi:10.1016/j.plaphy.2020.04.045

Abstract

The stomata of maize (Zea mays) contain a pair of guard cells and a pair of subsidiary cells. To determine whether H2O2, Ca2+, and K+ in subsidiary cells were involved in stomatal movement, we treated four-week-old maize (Zhengdan 958) leaves with H2O2, diphenylene iodonium (DPI), CaCl2, and LaCl3. Changes in content and distribution of H2O2, Ca2+, and K+ during stomatal movement were observed. When exogenous H2O2 was applied, Ca2+ increased and K+ decreased in guard cells, while both ions increased in subsidiary cells, leading to stomatal closure. After DPI treatment, Ca2+ decreased and K+ increased in guard cells, but both Ca2+ and K+ decreased in subsidiary cells, resulting in open stomata. Exogenous CaCl2 increased H2O2 and reduced K+ in guard cells, while significantly increasing them in subsidiary cells and causing stomatal closure. After LaCl3 treatment, H2O2 decreased and K+ increased in guard cells, whereas both decreased in subsidiary cells and stomata became open. Results indicate that H2O2 and Ca2+ correlate positively with each other and with K+ in subsidiary cells during stomatal movement. Both H2O2 and Ca2+ in subsidiary cells promote an inflow of K+, indirectly regulating stomatal closure.

Highlights

The stomata of maize ( Zea mays ) contain a pair of guard cells and a pair of subsidiary cells
When exogenous H 2 O 2 was applied, Ca 2+ increased and K + decreased in guard cells, while both ions increased in subsidiary cells, leading to stomatal closure
These results indicated that H 2 O 2 and Ca 2+ were correlated positively with each other and with K + in subsidiary cells during stomatal movement

Summary

Introduction

The stomata of maize ( Zea mays ) contain a pair of guard cells and a pair of subsidiary cells. In the stomata of maize (Zea mays),, a pair of guard cells surrounds a pair of subsidiary cells, which are thought to be donors and receptors of large amounts of water and ions [3] and assist in stomatal movement [4]. Stomatal closure resulted from the accumulation of H2O2 in subsidiary cells of maize leaves epidermis following a drought period [14]. Calcium ions have been found to regulate stomatal movement [18], with Ca2+ content in guard cells increasing following application of exogenous H2O2, and leading to stomatal closure [19]. K+ accumulates in guard cells following entry through its channel, resulting in a lower osmotic potential, water absorption, cell expansion, and stomatal opening [20]. Stomatal aperture changes may vary with the changes in H2O2, K+, and Ca2+ content in guard and subsidiary cells

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Discussion

Conclusion