Systematic deletion of the ER lectin chaperone genes reveals their roles in vegetative growth and male gametophyte development in Arabidopsis

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.

Root hairs enhance Arabidopsis seedling survival upon soil disruption

“… 0.28 ± 0.16 Supplementary Table S1 Root hair diameter c (μm) 9.9 ± 2.2 26 – 29 Primary root length c (cm) 0.72 ± 0.4 70.15 ± 0.88 Supplementary Table S1 , 30 – 33 Primary root diameter c (μm) 126.5 ± 36.8 145.3 ± 41.2 Supplementary Table S1 , 27 , 28 , 34 – 39 Total lateral root length c (cm/seedling) N.A. 5.93 ± 0.20 32 , 33 Lateral root diameter c (μm) N.A. 126.7 ± 47.1 Supplementary Table S1 , 35 – 38 Total length of root tip regions lacking root hair c (mm/seedling) 0.95 ± 0.1 13.25 ± 1.7 Supplementary Table S1 , 30 , 31 , 33 , 40 Epidermal (H-) cell length c (μm) 146.2 ± 36.1 191.5 ± 44.2 Supplementary Table S1 , 27 , 34 , 35 , 39 Epidermal (H-) cell length of lateral root d (μm) N.A.…”

“… 126.7 ± 47.1 Supplementary Table S1 , 35 – 38 Total length of root tip regions lacking root hair c (mm/seedling) 0.95 ± 0.1 13.25 ± 1.7 Supplementary Table S1 , 30 , 31 , 33 , 40 Epidermal (H-) cell length c (μm) 146.2 ± 36.1 191.5 ± 44.2 Supplementary Table S1 , 27 , 34 , 35 , 39 Epidermal (H-) cell length of lateral root d (μm) N.A. 137.4 ± 17.5 Supplementary Table S1 Root hair density (hair No./mm root) 47.5 43.6 Total surface area of root hairs (mm 2 /seedling) 4.53 51.93 Total surface area of root (mm 2 /seedling) 7.39 107.55 Ratio of root hair surface area e (%) 61.3 48.6 a Among the accessions used in 15 references, 12 were Columbia-0 (Col-0) 26 – 30 , 32 , 33 , 35 , 37 – 40 and three were Landsberg erecta (L er ) 31 , 34 , 36 . Root hair densities were similar between Col-0 and L er 31 , 41 – 43 .…”

“… a Among the accessions used in 15 references, 12 were Columbia-0 (Col-0) 26 – 30 , 32 , 33 , 35 , 37 – 40 and three were Landsberg erecta (L er ) 31 , 34 , 36 . Root hair densities were similar between Col-0 and L er 31 , 41 – 43 .…”

Brassinosteroid‐mediated reactive oxygen species are essential for tapetum degradation and pollen fertility in tomato

“…The development and environmental adaptation of higher plant pollen are influenced by a series of processes, wherein phytohormonal regulation, carbohydrate accumulation and metabolism play critical roles (Cecchetti et al , ; Vu et al , ). Arabidopsis thaliana mutants impaired in auxin transporters ABCB 1 /PGP 1 and ABCB 19 /PGP 19 are defective in stamen development (Cecchetti et al , ).…”

“…In addition, defects in autophagy result in the decreased accumulation of endogenous gibberellins (GAs) in anthers, delayed tapetal programmed cell death (PCD) and abnormal pollen morphology in rice (Kurusu et al , ). Moreover, the calnexin triple mutant, crt1 crt2 crt3 , shows impaired pollen viability and pollen tube growth in Arabidopsis (Vu et al , ).…”