Screening And Identification Of Arabidopsis Mutants Related To Stomatal Responses To Climatic Factors

Climatic factors mainly include relative air humidity,CO₂ concentration and air temperature etc.,which affect the physiological,and biochemical processes,growth and development of plants.Under abiotic stresses,plants guard cells could sense and transduce the signals,then respond to them by adjusting the stomatal aperture.Screening mutants involving in stomatal signal transduction is one of the most direct and effective methods for the characterization of gene functions.In this study,we verified the feasibility of our developed and patented chamber for elucidating the rules of stomatal dynamic movements after challenged by climatic factors.We screened 68 mutant candidates from Arabidopsis SALK T-DNA population utilizing the infrared camera and the chamber with well-controlled environments.Plant stomata will close in response to reduced atmospheric humidity,which was found110 years ago,however there remains unclear on the mechanism underlying this process until now.To clarify it,we identified two stomatal mutants called as c1 and c2 showing a lesion in responding to a drop in humidity.Our studies indicated that a T-DNA fragment was inserted into the region of At5g49370 gene in c1 mutant and stomatal density was significantly greater than the wild type.Gene mapping studies also shows that a T-DNA fragment was inserted into the region of At2g14160 gene in c2 mutant.C2 gene encodes an 85-amino-acids protein which harbors a RNA-binding motif?RRM/RBD/RNP?and belongs to RNA-binding gene family.We then confirmed the mutant phenotype by photosynthesis analyzer,infrared camera and measurements in water loss.Peels of c2 mutant then was subjected to ABA and Ca²⁺.The results showed that C2 was insensitive to ABA and Ca²⁺,indicating C2 might function in the downstream of Ca²⁺in ABA signaling pathway.Further studies revealed that C2 gene is upregulated by dehydration treatment,while the expression levels of C2 gene and most of key genes in ABA signaling pathway reduced in c2 mutant.Our data would deepen the understanding of C1 and C2 functions and build a key foundation for the clarification of the mechanism during stomatal response to low air humidity.