The Mutation of Glu at Amino Acid 3838 of AtMDN1 Provokes Pleiotropic Developmental Phenotypes in Arabidopsis

Abstract

MDN1/Rea1, as an AAA-type ATPase, is predicted to be the largest protein involved in pre-ribosome maturation in most organisms. However, its function in plant growth and development is poorly understood. Here, we characterized a novel Arabidopsis mutant, dwarf & short root (dsr) 1, which shows pleiotropic developmental phenotypes, such as slow germination, short root, dwarf shoot, and reduced seed set under normal growth conditions. Using positional cloning, we revealed that the AtMDN1 function is impaired by a ‘glutamic acid’ to ‘lysine’ change at position 3838 of the amino acid sequence in dsr1. Multiple sequence alignment analysis revealed that the mutated Glu residue, which located in the linker domain of AtMDN1, is extremely conserved among organisms. AtMDN1 is expressed in various tissues, particularly in the shoot apex and root tip. Moreover, the results of transcript profile analyses showed that the dysfunction of AtMDN1 in dsr1 impairs the expression of genes related to plant growth and development, which is tightly associated with the pleiotropic phenotypes of dsr1. Thus, we concluded that the Glu residue plays a vital role in maintaining AtMDN1 functions, which are essential for plant growth and development.

The AAA-ATPase MIDASIN 1 Functions in Ribosome Biogenesis and Is Essential for Embryo and Root Development

“…1A). The phenotype of the mdn1-1 silique has been presented in our previous study (Li et al, 2016b). As described by Chantha et al (2010), a heterozygous T-DNA insertion mutant allele of MDN1 (Salk_057010), which we call "mdn1-2/+" in this study, also exhibits the phenotype of reduced seed set per silique.…”

“…In maize (Zea mays), the reduced function of RIBOSOME EXPORT ASSO-CIATED1 (the counterpart of MDN1) results in delayed embryo, endosperm, and seedling development (Qi et al, 2016). Furthermore, we previously characterized an Arabidopsis mutant, dwarf and short root (dsr1; renamed mdn1-1 in this study), which contained a missense mutation in MDN1 and displayed phenotypes such as a short root and low seed set under normal growth conditions (Li et al, 2016b). These results imply that MDN1 is also vital for normal plant growth and development.…”

“…These results imply that MDN1 is also vital for normal plant growth and development. Through transcript profile analyses, we found that many biological processes were affected in mdn1-1 (Li et al, 2016b). Nevertheless, the molecular function of MDN1 in Arabidopsis remains poorly understood.…”

Whole Root Transcriptomic Analysis Reveals a Role for Auxin Pathways in Resistance toRalstonia solanacearumin Tomato

“…In Arabidopsis, MCM2 is involved in DNA replication and is important for root meristem maintenance (Ni et al 2009), and mutations in a DNA helicase/nuclease result in very short roots (Jia et al 2016). Further, mutation of AtMDN1, an AAA-ATPase that is a component of the pre-60S ribosome, results in several developmental defects including a shorter root (Li et al 2016). Histone modifications have also been shown to be critical for proper root growth and development (reviewed in Takatsuka and Umeda 2015).…”

Ribosome Biogenesis in Plants: From Functional 45S Ribosomal DNA Organization to Ribosome Assembly Factors

“…No plant homologs of yeast Rsa4 have thus far been reported. However, characterization of the dwarf and short root1 (dsr1) mutant revealed that DSR1 is the Arabidopsishomolog of the yeast Rea1 and human MDN1 proteins (Li et al, 2016). Mutating a key amino acid position in ArabidopsisMDN1 (Glu to Lys at position 3838) induces pleiotropic developmental phenotypes, including slow germination, short roots, dwarf shoots, and reduced seed set (Li et al, 2016).…”