AtLSG1-2 Regulates Leaf Growth by Affecting Cell Proliferation and the Onset of Endoreduplication and Synergistically Interacts with AtNMD3 during Cell Proliferation Process.

Huayan Zhao,Liming Xiong,Shiyou Lü

doi:10.3389/fpls.2017.00337

Abstract

AtLSG1-2 is a circularly permuted GTPase required for ribosome biogenesis and recently shown to be involved in early leaf development, although it was unclear how AtLSG1-2 affects leaf growth. Here, we found that atlsg1-2 mutants had reduced leaf size as a result of decreased cell size and cell number. Leaf kinematic analysis and CYCB1;1::GUS expression pattern in atlsg1-2 mutant indicated that loss of function of AtLSG1-2 delays the transition from cell division to cell expansion. Decreases in ploidy levels and trichome branch number suggest that AtLSG1-2 deficiency suppresses endoreduplication. Real-time PCR analysis showed that genes specifically expressed in the proliferation stage were highly expressed and those involved in endoreduplication were differentially regulated. LSG1 is known to mediate the recruitment of nucleocytoplasmic shuttling protein NMD3 back to the nucleus in yeast, yet their relationship was unclear in plants. Our genetic analysis revealed that the atlsg1 atnmd3 double mutant displayed enhanced phenotypes as compared with the respective single mutant and that AtLSG1-2 and AtNMD3 synergistically affect the cell proliferation process.

Highlights

The leaves of higher plants are important structures where photosynthesis takes place that provides carbon and energy for plant growth
Small-Sized atlsg1-2 Leaves Are Caused by Reduced Cell Size and Cell Number
Because cell expansion is closely related with the endoreduplication process, we examined the ploidy distribution by flow cytometry in the first pair of wild-type and atlsg1-2 mutant leaves

Summary

Introduction

The leaves of higher plants are important structures where photosynthesis takes place that provides carbon and energy for plant growth. Leaf development is a complicated process that is coordinately regulated by internal factors and environmental conditions. The final size of a leaf is determined by two factors: cell size and cell number. Cell size is influenced by vacuolar volume, cell wall expansion, macromolecular synthesis in the cytoplasm and nuclei size (Marshall et al, 2012). Many genes that control cell size, cell number or both have been identified (Kessler and Sinha, 2004; Gonzalez et al, 2012; Weis et al, 2015). Genes controlling cell division include, for example, transcription factor genes, microRNAs, genes involved in hormone

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