Chromium stress response effect on signal transduction and expression of signaling genes in rice

Abstract

Hexavalent chromium [Cr(VI)] is a non-essential metal for normal plants and is toxic to plants at high concentrations. However, signaling pathways and molecular mechanisms of its action on cell function and gene expression remain elusive. In this study, we found that Cr(VI) induced endogenous reactive oxygen species (ROS) generation and Ca(2+) accumulation and activated NADPH oxidase and calcium-dependent protein kinase. We investigated global transcriptional changes in rice roots by microarray analysis. Gene expression profiling indicated activation of abscisic acid-, ethylene- and jasmonic acid-mediated signaling and inactivation of gibberellic acid-related pathways in Cr(VI) stress-treated rice roots. Genes encoding signaling components such as the protein kinases domain of unknown function 26, receptor-like cytoplasmic kinase, LRK10-like kinase type 2 and protein phosphatase 2C, as well as transcription factors WRKY and apetala2/ethylene response factor were predominant during Cr(VI) stress. Genes involved in vesicle trafficking were subjected to functional characterization. Pretreating rice roots with a vesicle trafficking inhibitor, brefeldin A, effectively reduced Cr(VI)-induced ROS production. Suppression of the vesicle trafficking gene, Exo70, by virus-induced gene silencing strategies revealed that vesicle trafficking is required for mediation of Cr(VI)-induced ROS production. Taken together, these findings shed light on the molecular mechanisms in signaling pathways and transcriptional regulation in response to Cr stress in plants.

Role of Ethylene and Its Cross Talk with Other Signaling Molecules in Plant Responses to Heavy Metal Stress

“…The Cu-inducible expression of the ACS genes in potato (Solanum tuberosum) and the accumulation of the ACS transcripts in different varieties of tobacco (Nicotiana tabacum) have been reported . Recently, transcriptome analysis of chromium-treated rice (Oryza sativa) roots also indicated enhanced expression of four ethylene biosynthesis-related genes (ACS1, ACS2, ACO4, and ACO5), suggesting the participation of ethylene in chromium signaling in rice (Steffens, 2014;Trinh et al, 2014). These findings together demonstrated that ethylene is enhanced in response to various Figure 1.…”

Transcriptome Profiling and Physiological Studies Reveal a Major Role for Aromatic Amino Acids in Mercury Stress Tolerance in Rice Seedlings

“…Total RNA extraction involved use of the RNeasy Plant Mini kit (QIAGEN, Hilden, Germany) following the manufacturer’s instructions with some modifications. Semi-quantitative RT-PCR and quantitative RT-PCR (qRT-PCR) reactions were performed as previously described [13]. Relative quantification of specific mRNA levels was analyzed using the cycle threshold (Ct) (2 −ΔΔCt ) method [14].…”

Exogenous abscisic acid alleviates zinc uptake and accumulation in Populus × canescens exposed to excess zinc

“…; Trinh et al . ). Exogenous ABA application has been reported to reduce transpiration, leading to reduced Zn translocation from the soil to the aerial parts of plants, and to enhance the heavy metal tolerance of plants via defence priming in plants (Hsu & Kao 2003, 2005, 2008; Zhao et al .…”

“…ABA is involved in defence priming in plants (Luo et al 2009) and can activate antioxidative defence systems that contribute to the alleviation of heavy metal toxicity (Sharma & Kumar 2002;Wang et al 2013). Moreover, elevated ABA levels in plants can trigger the signalling cascades downstream of phytohormones, such as salicylic acid (SA) and auxin (IAA), which may also mitigate heavy metal-induced toxicity (Stroinski et al 2010;Noriega et al 2012;Disante et al 2014;Trinh et al 2014). Exogenous ABA application has been reported to reduce transpiration, leading to reduced Zn translocation from the soil to the aerial parts of plants, and to enhance the heavy metal tolerance of plants via defence priming in plants (Hsu & Kao 2003, 2008Zhao et al 2009).…”