Functional Analyses Of Mechanosensitive Channel Piezo In Plants

As sessile organisms,most plants must deal with various unfavorable environmental cues.Among a variety of environmental conditions,mechanical stimuli,such as turgor pressure,gravity,touch,winding,raining,injury,insect feeding,and space obstacle,affect and determine the growth and development of plants.Therefore,plants have developed a mechanism of sensing and responding to mechanical stimuli.At present,it is believed that mechanosensitive ion channels play an important role in the perception of mechanical signals in plants.In the past decade,a series of breakthroughs have been made in the research of mechanosensitive ion channel Piezo in animals.As a mechanically sensitive ion channel,Piezo plays an important role in touch perception,proprioception,blood pressure regulation,and proliferation and pressure sensing in nerve cells.Interestingly,bioinformatic analyses indicate that Piezo genes also exist in plants.In this study,we systematically studied the potential functions of the homologous gene of animal Piezo in plants using Arabidopsis thaliana and maize as model plants.By analyzing the expression patterns of At Piezo in Arabidopsis,we found that At Piezo was expressed in root cap,guard cell,pollen and other tissues and organs.When At Piezo was transiently transformed into Arabidopsis protoplasts,At Piezo protein was detected to be localized at tonoplast.The genetic and physiological experiments proved that At Piezo plays a role in the mechanical perception in root and showed that At Piezo is involved in regulating the flow of calcium ions in root cap.This study also preliminarily revealed that At Piezo may play a role in touch perception and pollen germination.In addition to Arabidopsis,the dicot model plant,this study explored the functions of Piezo gene in maize,a monocot model plant.Our results showed that Zm Piezo is highly expressed in root tips in maize.By constructing the Zm Piezo loss-of-function mutants,it was found that the rooting ability of the zmpiezo mutant was partially impaired,leading to altered root development compared to wild-type plants.It indicated that Zm Piezo might affect the root architecture through the perception of mechanical stimuli in soil.This study also found that Zm Piezo is also involved in regulating the pollen germination in maize.Through the functional analyses of Piezo homologous genes in Arabidopsis and maize,this study preliminarily revealed that Piezo genes in plants play a critical role in responding to mechanical signals,similar to their homologs in animals.Unlike in animals,the Piezo is not indispensable to plants,which may be due to the differences in the cell structures and responses to mechanical stimuli in plants and animals during evolution.Therefore,the analyses of the functions of plant Piezo in this study may contribute to our better understanding of the molecular mechanisms of mechanical perception and response in plants.