Systematic deletion of the ER lectin chaperone genes reveals their roles in vegetative growth and male gametophyte development in Arabidopsis |
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Authors: | Kien Van Vu Ngoc Trinh Nguyen Chan Young Jeong Yong‐Hwa Lee Hojoung Lee Suk‐Whan Hong |
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Institution: | 1. Department of Molecular Biotechnology, College of Agriculture and Life Sciences, Bioenergy Research Institute, Chonnam National University, Gwangju, Korea;2. Department of Molecular Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea;3. National Institute of Crop Science, Bioenergy Crop Research Center, Muan, Jeonnam, Korea |
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Abstract: | Calnexin (CNX) and calreticulin (CRT) are homologous lectin chaperones in the endoplasmic reticulum (ER) that facilitate glycoprotein folding and retain folding intermediates to prevent their transit via the secretary pathway. The Arabidopsis genome has two CNX (CNX1 and CNX2) and three CRT (CRT1, CRT2 and CRT3) homologs. Despite growing evidence of the biological roles of CNXs and CRTs, little is understood about their function in Arabidopsis growth and development under normal conditions. Here, we report that the deletion of CNX1, but not of CNX2, in the crt1 crt2 crt3 triple mutation background had an adverse effect on pollen viability and pollen tube growth, leading to a significant reduction in fertility. The cnx1 crt1 crt2 crt3 quadruple mutation also conferred severe defects in growth and development, including a shortened primary root, increased root hair length and density, and reduced plant height. Disruption of all five members of the CNX/CRT family was revealed to be lethal. Finally, the abnormal phenotype of the cnx1 crt1 crt2 crt3 quadruple mutants was completely rescued by either the CNX1 or CNX2 cDNA under the control of the CNX1 promoter, suggesting functional redundancy between CNX1 and CNX2. Taken together, these results provide genetic evidence that CNX and CRT play essential and overlapping roles during vegetative growth and male gametophyte development in Arabidopsis. |
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Keywords: | Arabidopsis CNX/CRT cycle endoplasmic reticulum secretory pathway protein folding quality control |
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