Project description:Root exudates play an important role in plant-microbe interaction. The transcriptional profilings of plant growth-promoting rhizobacteria Bacillus amyloliquefaciens SQR9 in response to maize root exudates under static condition, were investigated by an Illumina RNA-seq for understanding the regulatory roles of the root exudates.
Project description:Plants are naturally associated with diverse microbial communities, which play significant roles in plant performance, such as growth promotion or fending off pathogens. The roots of Alkanna tinctoria L. are rich in naphthoquinones, particularly the medicinally used chiral compounds alkannin, shikonin and their derivatives. Former studies already have shown that microorganisms may modulate plant metabolism. To further investigate the potential interaction between A. tinctoria and associated microorganisms we performed a greenhouse experiment, in which A. tinctoria plants were grown in the presence of three distinct soil microbiomes. At four defined plant developmental stages we made an in-depth assessment of bacterial and fungal root-associated microbiomes as well as all primary and secondary metabolites. Our results showed that the plant developmental stage was the most important driver influencing the plant metabolite content, revealing peak contents of alkannin/shikonin at the fruiting stage. In contrast, the soil microbiome had the biggest impact on the plant root microbiome. Correlation analyses performed on the measured metabolite content and the abundance of individual bacterial and fungal taxa suggested a dynamic, at times positive or negative relationship between root-associated microorganisms and root metabolism. In particular, the bacterial Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium group and the fungal species Penicillium jensenii were found to be positively correlated with higher content of alkannins.
Project description:The root system is a crucial determinant of plant growth potential because of its important functions, e.g., acquisition of water and nutrients, structural support, and interaction with symbiotic organisms. Elucidating the molecular mechanisms of root development and functions is therefore necessary for improving plant productivity, particularly for crop plants including rice. As an initial step towards developing a comprehensive understanding of the root system, we performed a large-scale transcriptome analysis of the rice root via a combined laser microdissection and microarray analysis approach.
Project description:Aim: To determine the effect of an AtrbohC mutation on the gene expression pattern in primary root tissue, to identify candidate genes acting downstream of AtrbohC, particularly any encoding antioxidant-related proteins, signal transduction components or proteins known to be required for normal root-hair development. Background: Root-hairs are a model system for investigating plant cell polarity. The root-hair mutant rhd2 (Schiefelbein and Somerville, 1990. Plant Cell, 2:235) has short hairs that burst at their tips, (Jones and Smirnoff, unpublished). RHD2 has been cloned and is identical to AtrbohC (L. Dolan, pers. comm.), which encodes a homologue of the superoxide-generating neutrophil respiratory burst oxidase catalytic subunit gp91phox (Torres et al., 1998. Plant J., 14:365). Superoxide rapidly dismutates to hydrogen peroxide (H2O2), suggesting that the rhd2 phenotype may result from reduced H2O2 levels in root-hair cells. Low doses of exogenous antioxidants phenocopy the rhd2 root-hair phenotype in wild-type plants (Jones and Smirnoff, unpublished) further supporting a role for H2O2 in root-hair growth. Fluorescent dyes that detect H2O2 show distinct localisation patterns in growing root-hair cells, (Jones and Smirnoff, unpublished). H2O2 may be an important second messenger in plant cell signalling with proposed roles in the development of cotton fibres (Potikha et al., 1999. Plant Physiol., 119: 849) and in ABA-induced stomatal closure (Zhang et al., 2001. Plant Physiol., 126: 1438). In cultured Arabidopsis cells H2O2 induces gene expression, including that of a gp91phox homologue, (Desikan et al., 1998. J. Exp. Bot., 49: 1767; Desikan, et al., 2000. Free Rad. Biol. Med., 28: 773; Baxter-Burrell et al., 2002. Science, 296: 2026) and activates a MAP kinase cascade (Desikan et al., 1999. J. Exp Bot., 50: 1863). cDNA microarray technology has been used previously to examine the effects of H2O2 on gene expression during oxidative stress (Desikan et al., 2001. Plant Physiol., 127: 159). We wish to investigate the effects of H2O2 on gene expression during root development using the rhd2 mutant. We are currently determining the expression pattern of RHD2. By extracting RNA from the small region of the primary root (for wild-type and rhd2 plants grown in sterile conditions) where root hairs are growing we hope to enrich for root-hair RNAs. This may reveal candidate genes that could be examined more closely at the single-cell level. This approach will provide new insights into the role of H2O2 in root-hair development. Keywords: strain_or_line_design