Cell division and turgor mediate enhanced plant growth in Arabidopsis plants treated with the bacterial signalling molecule lumichrome

Abstract

Transcriptomic analysis indicates that the bacterial signalling molecule lumichrome enhances plant growth through a combination of enhanced cell division and cell enlargement, and possibly enhances photosynthesis. Lumichrome (7,8 dimethylalloxazine), a novel multitrophic signal molecule produced by Sinorhizobium meliloti bacteria, has previously been shown to elicit growth promotion in different plant species (Phillips et al. in Proc Natl Acad Sci USA 96:12275-12280, https://doi.org/10.1073/pnas.96.22.12275 , 1999). However, the molecular mechanisms that underlie this plant growth promotion remain obscure. Global transcript profiling using RNA-seq suggests that lumichrome enhances growth by inducing genes impacting on turgor driven growth and mitotic cell cycle that ensures the integration of cell division and expansion of developing leaves. The abundance of XTH9 and XPA4 transcripts was attributed to improved mediation of cell-wall loosening to allow turgor-driven cell enlargement. Mitotic CYCD3.3, CYCA1.1, SP1L3, RSW7 and PDF1 transcripts were increased in lumichrome-treated Arabidopsis thaliana plants, suggesting enhanced growth was underpinned by increased cell differentiation and expansion with a consequential increase in biomass. Synergistic ethylene-auxin cross-talk was also observed through reciprocal over-expression of ACO1 and SAUR54, in which ethylene activates the auxin signalling pathway and regulates Arabidopsis growth by both stimulating auxin biosynthesis and modulating the auxin transport machinery to the leaves. Decreased transcription of jasmonate biosynthesis and responsive-related transcripts (LOX2; LOX3; LOX6; JAL34; JR1) might contribute towards suppression of the negative effects of methyl jasmonate (MeJa) such as chlorophyll loss and decreases in RuBisCO and photosynthesis. This work contributes towards a deeper understanding of how lumichrome enhances plant growth and development.

A Sheathed Spike Gene, TaWUS-like Inhibits Stem Elongation in Common Wheat by Regulating Hormone Levels

“…As previous reports, the division and elongation of plant cells are closely related to the function of Cyclins and Expansins in plants [14]. Here, the expression levels of Cyclins and Expansins were signi cantly reduced in TaWUS-like-OE lines.…”

AtCAF‐1 mutants show different DNA damage responses after ultraviolet‐B than those activated by other genotoxic agents in leaves

“…In addition, XTH9 and XTH22 were different in WT compared with CAF‐1 mutants (Figure c,d). Increased XTH9 expression was reported to improve cell‐wall loosening to allow rearrangement of the cell wall and subsequent cell expansion (Pholo et al, ). XTH enzymes have the potential to control plant cell growth; thus, changes in cell size measured after UV‐B exposure in fas1 and fas2 mutants could be due to differences in XTH levels and activities.…”

Increased algicidal activity of Aeromonas veronii in response to Microcystis aeruginosa: interspecies crosstalk and secondary metabolites synergism

“…Although, it has a different structure then N ‐acyl homoserine lactones implicated in bacterial quorum sensing, it was found that it can activate, with up to 40% effectiveness, the bacterial receptor LasR, by entering the same active site in the protein as the signal molecule 3‐oxo‐C12‐HSL (Rajamani et al ., ). Lumichrome also affects the development of plants (Pholo et al ., ) by an unknown mechanism that resembles the plant hormone abscisic acid (Dakora et al ., ).…”