Two Expansin Genes, AtEXPA4 and AtEXPB5, Are Redundantly Required for Pollen Tube Growth and AtEXPA4 Is Involved in Primary Root Elongation in Arabidopsis thaliana.

Weimiao Liu,Jiashu Cao,Hui Lin,Liai Xu

doi:10.3390/genes12020249

Abstract

The growth of plant cells is inseparable from relaxation and expansion of cell walls. Expansins are a class of cell wall binding proteins, which play important roles in the relaxation of cell walls. Although there are many members in expansin gene family, the functions of most expansin genes in plant growth and development are still poorly understood. In this study, the functions of two expansin genes, AtEXPA4 and AtEXPB5 were characterized in Arabidopsis thaliana. AtEXPA4 and AtEXPB5 displayed consistent expression patterns in mature pollen grains and pollen tubes, but AtEXPA4 also showed a high expression level in primary roots. Two single mutants, atexpa4 and atexpb5, showed normal reproductive development, whereas atexpa4 atexpb5 double mutant was defective in pollen tube growth. Moreover, AtEXPA4 overexpression enhanced primary root elongation, on the contrary, knocking out AtEXPA4 made the growth of primary root slower. Our results indicated that AtEXPA4 and AtEXPB5 were redundantly involved in pollen tube growth and AtEXPA4 was required for primary root elongation.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
By exploring phenotypes of mutants and overexpression lines, we found that AtEXPA4 and AtEXPB5 are redundantly involved in pollen tube elongation, and AtEXPA4 plays a positive role in primary root growth
The results showed that AtEXPA4 seemed to expressed ubiquitously (Figure 1A), but its expression level was higher in inflorescences and roots (Figure 1A,B)

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Plant growth and development are inseparable from cell proliferation and expansion. Different from animal cells, plant cells are surrounded by cell walls, which are highly dynamic and complex networks [1]. Cells are always in a dynamic balance between the expansion of protoplasts and the restraint of cell walls, undergoing irreversible growth [2]

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Discussion

Conclusion