Transcriptional profiling of aluminum toxicity and tolerance responses in maize roots

Plant perception of pathogen-associated molecular patterns (PAMPs) and other environmental stresses trigger transient ion fluxes at the plasma membrane. Apart from the role of Ca 2+ uptake in signaling, the regulation and significance of PAMPinduced ion fluxes in immunity remain unknown. We characterized the functions of INTEGRIN-LINKED KINASE1 (ILK1) that encodes a Raf-like MAP2K kinase with functions insufficiently understood in plants. Analysis of ILK1 mutants impaired in the expression or kinase activity revealed that ILK1 contributes to plant defense to bacterial pathogens, osmotic stress sensitivity, and cellular responses and total ion accumulation in the plant upon treatment with a bacterial-derived PAMP, flg22. The calmodulin-like protein CML9, a negative modulator of flg22-triggered immunity, interacted with, and suppressed ILK1 kinase activity. ILK1 interacted with and promoted the accumulation of HAK5, a putative (H + )/K + symporter that mediates a high-affinity uptake during K + deficiency. ILK1 or HAK5 expression was required for several flg22 responses including gene induction, growth arrest, and plasma membrane depolarization. Furthermore, flg22 treatment induced a rapid K + efflux at both the plant and cellular levels in wild type, while mutants with impaired ILK1 or HAK5 expression exhibited a comparatively increased K + loss. Taken together, our results position ILK1 as a link between plant defense pathways and K + homeostasis.

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“…The dried tissue was homogenized and analyzed by inductively coupled plasma emission spectrometry as previously described in Maron et al (2008).…”

Section: Ion Content Measurementmentioning

confidence: 99%

The Raf-like kinase ILK1 and the high affinity K+ transporter HAK5 are required for Innate Immunity and Abiotic Stress Response

et al. 2016

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“…The physiological aspects for Al resistance have been well studied, but the molecular regulatory mechanisms controlling the Al response are not completely known. In maize, a monocot plant species like rice, more genes were found in the Al-sensitive genotype than in the Al-tolerant genotype (Maron et al, 2008). However, a citrate-exclusion mechanism was suggested to release toxic Al in maize, which is known to be different for rice (Khan et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Aluminum triggers broad changes in microRNA expression in rice roots

Lima

Arenhart²,

Margis‐Pinheiro³

et al. 2011

Genet. Mol. Res.

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ABSTRACT. MicroRNAs are small 21-nucleotide RNA molecules with regulatory roles in development and in response to stress. Expression of some plant miRNAs has been specifically associated with responses to abiotic stresses caused by cold, light, iron, and copper ions. In acid soils, aluminum solubility increases, thereby causing severe damage to plants. Although physiological aspects of aluminum toxicity in plants have been well characterized, the molecular mediators are not fully elucidated. There have been no reports about miRNA responses to aluminum stress. Modulation of miRNA expression may constitute a key element to explain the mechanisms implicated in aluminum toxicity and tolerance. We examined the expression of at least one miRNA member from each miRNA family in rice roots of Oryza sativa spp indica cv. Embrapa Taim and Oryza sativa spp japonica cv. Nipponbare under high concentrations of aluminum. Forty-six miRNA families were effectively detected by quantitative PCR. Among these, 13 were down-regulated and six were up-regulated in roots of the Nipponbare cultivar after 8 h of aluminum treatment. In roots of the Embrapa Taim cultivar, five miRNAs were down-regulated and three were upregulated. Analyses of their putative targets suggest that these rice miRNAs are involved in the regulation of various metabolic pathways in response to high concentrations of aluminum.

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“…We recently reported on the characterization of the maize Al tolerance gene MATE1 (15), originally identified in a microarray study (16) as the most up-regulated gene in root tips of an Al-tolerant maize line under Al stress. MATE1 was mapped to the telomeric region of chromosome 6, colocalizing with the QTL of largest effect on Al tolerance identified by Ninamango-Cárdenas et al (14), explaining 16.2% of the phenotypic variance.…”

mentioning

confidence: 99%

Aluminum tolerance in maize is associated with higherMATE1gene copy number

Maron

Guimarães

Kirst

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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271

221

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Genome structure variation, including copy number variation and presence/absence variation, comprises a large extent of maize genetic diversity; however, its effect on phenotypes remains largely unexplored. Here, we describe how copy number variation underlies a rare allele that contributes to maize aluminum (Al) tolerance. Al toxicity is the primary limitation for crop production on acid soils, which make up 50% of the world's potentially arable lands. In a recombinant inbred line mapping population, copy number variation of the Al tolerance gene multidrug and toxic compound extrusion 1 (MATE1) is the basis for the quantitative trait locus of largest effect on phenotypic variation. This expansion in MATE1 copy number is associated with higher MATE1 expression, which in turn results in superior Al tolerance. The three MATE1 copies are identical and are part of a tandem triplication. Only three maize inbred lines carrying the three-copy allele were identified from maize and teosinte diversity panels, indicating that copy number variation for MATE1 is a rare, and quite likely recent, event. These maize lines with higher MATE1 copy number are also Al-tolerant, have high MATE1 expression, and originate from regions of highly acidic soils. Our findings show a role for copy number variation in the adaptation of maize to acidic soils in the tropics and suggest that genome structural changes may be a rapid evolutionary response to new environments. abiotic stress | selection

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Transcriptional profiling of aluminum toxicity and tolerance responses in maize roots

Cited by 129 publications

References 58 publications

The Raf-like kinase ILK1 and the high affinity K+ transporter HAK5 are required for Innate Immunity and Abiotic Stress Response

The Raf-like kinase ILK1 and the high affinity K+ transporter HAK5 are required for Innate Immunity and Abiotic Stress Response

Aluminum triggers broad changes in microRNA expression in rice roots

Aluminum tolerance in maize is associated with higherMATE1gene copy number

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