Abstract:The development of the plant root system is highly plastic, which allows the plant to adapt to various environmental stresses. Salt stress inhibits root elongation by reducing the size of the root meristem. However, the mechanism underlying this process remains unclear. In this study, we explored whether and how auxin and nitric oxide (NO) are involved in salt-mediated inhibition of root meristem growth in Arabidopsis (Arabidopsis thaliana) using physiological, pharmacological, and genetic approaches. We found… Show more
“…Treatment with SA reduces auxin responses by stabilizing Aux/IAA proteins (Wang et al, 2007). Gain-of-function mutations of Aux/IAA proteins such as IAA3 and IAA17 induce defective root development Liu et al, 2015). We found that MHPP treatment enhanced the degradation of Aux/IAA proteins, as revealed by GUS staining of the HS:AXR3-GUS reporter line, and thereby amplified auxin signaling in root tips.…”
Section: Discussion Mhpp Affects Root System Development By Modulatinmentioning
confidence: 62%
“…Treatment with the auxin transport inhibitor NPA or mutation of the PIN family of auxin carrier genes affects root growth (Blilou et al, 2005;Liu et al, 2015), and these observations suggest that disturbing PAT changes auxin accumulation in root tips and subsequently alters root growth. In this study, we found that NPA did not affect the MHPP-mediated inhibitory effects on PR elongation; this finding suggests that PAT is involved in MHPP-mediated root growth inhibition.…”
Section: Discussion Mhpp Affects Root System Development By Modulatinmentioning
confidence: 99%
“…Changes in Aux/IAA stability and, subsequently, the auxin perception level appear to represent a general strategy by which plants interplay with phytohormones and respond to environmental cues (Yuan et al, 2013;Bailly et al, 2014;Katz et al, 2015;Liu et al, 2015;Yuan and Huang, 2016). Treatment with SA reduces auxin responses by stabilizing Aux/IAA proteins (Wang et al, 2007).…”
Section: Discussion Mhpp Affects Root System Development By Modulatinmentioning
Methyl 3-(4-hydroxyphenyl)propionate (MHPP) is a root exudate that functions as a nitrification inhibitor and as a modulator of the root system architecture (RSA) by inhibiting primary root (PR) elongation and promoting lateral root formation. However, the mechanism underlying MHPP-mediated modulation of the RSA remains unclear. Here, we report that MHPP inhibits PR elongation in Arabidopsis (Arabidopsis thaliana) by elevating the levels of auxin expression and signaling. MHPP induces an increase in auxin levels by up-regulating auxin biosynthesis, altering the expression of auxin carriers, and promoting the degradation of the auxin/indole-3-acetic acid family of transcriptional repressors. We found that MHPP-induced nitric oxide (NO) production promoted reactive oxygen species (ROS) accumulation in root tips. Suppressing the accumulation of NO or ROS alleviated the inhibitory effect of MHPP on PR elongation by weakening auxin responses and perception and by affecting meristematic cell division potential. Genetic analysis supported the phenotype described above. Taken together, our results indicate that MHPP modulates RSA remodeling via the NO/ROS-mediated auxin response pathway in Arabidopsis. Our study also revealed that MHPP significantly induced the accumulation of glucosinolates in roots, suggesting the diverse functions of MHPP in modulating plant growth, development, and stress tolerance in plants.
“…Treatment with SA reduces auxin responses by stabilizing Aux/IAA proteins (Wang et al, 2007). Gain-of-function mutations of Aux/IAA proteins such as IAA3 and IAA17 induce defective root development Liu et al, 2015). We found that MHPP treatment enhanced the degradation of Aux/IAA proteins, as revealed by GUS staining of the HS:AXR3-GUS reporter line, and thereby amplified auxin signaling in root tips.…”
Section: Discussion Mhpp Affects Root System Development By Modulatinmentioning
confidence: 62%
“…Treatment with the auxin transport inhibitor NPA or mutation of the PIN family of auxin carrier genes affects root growth (Blilou et al, 2005;Liu et al, 2015), and these observations suggest that disturbing PAT changes auxin accumulation in root tips and subsequently alters root growth. In this study, we found that NPA did not affect the MHPP-mediated inhibitory effects on PR elongation; this finding suggests that PAT is involved in MHPP-mediated root growth inhibition.…”
Section: Discussion Mhpp Affects Root System Development By Modulatinmentioning
confidence: 99%
“…Changes in Aux/IAA stability and, subsequently, the auxin perception level appear to represent a general strategy by which plants interplay with phytohormones and respond to environmental cues (Yuan et al, 2013;Bailly et al, 2014;Katz et al, 2015;Liu et al, 2015;Yuan and Huang, 2016). Treatment with SA reduces auxin responses by stabilizing Aux/IAA proteins (Wang et al, 2007).…”
Section: Discussion Mhpp Affects Root System Development By Modulatinmentioning
Methyl 3-(4-hydroxyphenyl)propionate (MHPP) is a root exudate that functions as a nitrification inhibitor and as a modulator of the root system architecture (RSA) by inhibiting primary root (PR) elongation and promoting lateral root formation. However, the mechanism underlying MHPP-mediated modulation of the RSA remains unclear. Here, we report that MHPP inhibits PR elongation in Arabidopsis (Arabidopsis thaliana) by elevating the levels of auxin expression and signaling. MHPP induces an increase in auxin levels by up-regulating auxin biosynthesis, altering the expression of auxin carriers, and promoting the degradation of the auxin/indole-3-acetic acid family of transcriptional repressors. We found that MHPP-induced nitric oxide (NO) production promoted reactive oxygen species (ROS) accumulation in root tips. Suppressing the accumulation of NO or ROS alleviated the inhibitory effect of MHPP on PR elongation by weakening auxin responses and perception and by affecting meristematic cell division potential. Genetic analysis supported the phenotype described above. Taken together, our results indicate that MHPP modulates RSA remodeling via the NO/ROS-mediated auxin response pathway in Arabidopsis. Our study also revealed that MHPP significantly induced the accumulation of glucosinolates in roots, suggesting the diverse functions of MHPP in modulating plant growth, development, and stress tolerance in plants.
“…In another study, absence of ET and NO in apical root segments and cell suspension culture, respectively, caused ionic imbalance (Na + /K + ) that resulted in increased susceptibility to salinity stress [93]. AUX and NO involvement in inhibition of root meristem growth in salt-stressed Arabidopsis was revealed by Liu et al [94]. They reported that salinity stress repressed root meristem growth by inhibiting the expression of PINFORMED (PIN) genes, thereby reducing AUX levels.…”
Section: No-phytohormone Cross Talk Under Salinity Stressmentioning
Plants, being sessile, are concurrently exposed to various biotic and abiotic stresses. The perception of stress signals in plants involves a wide spectrum of signal transduction pathways that interact to induce tolerance against adverse environmental conditions. This functional overlapping among various stress signaling cascades also leads to the expression of genes that regulate biosynthesis or action of other hormones. Phytohormonal signals, activated by both developmental and environmental responses, play a crucial role to develop stress tolerance in plants. Nitric oxide (NO) is one of the major players in plant signaling networks. Emerging evidence supports that NO interplays with signaling pathways of auxins, gibberellins, abscisic acid, ethylene, jasmonic acid, brassinosteroids, and other plant hormones to control metabolism, growth, and development in plants. This chapter focuses on the current state of knowledge of cross talk between signaling pathways of NO and phytohormones in plants exposed to various abiotic stresses.
“…After 7 days of co-cultivation with V. dahliae in the presence of 100 mM NaCl, a greater number of root apex displayed pronounced GUS staining compared to control plants (Figure 3), indicating that increased auxin accumulation is associated with reduced inhibition of root growth in the presence of NaCl. A previous study showed that application of exogenous auxin led to increased length and cell number of root meristem in the presence of 100 mM NaCl (Liu et al 2015). 10.1080/21501203.2018.1448009-F0003Figure 3.Expression of GUS in root tips of transgenic A. thaliana Col-0 containing DR5::GUS .…”
Volatile compounds (VCs) produced by diverse microbes seem to affect plant growth, development and/or stress tolerance. We investigated how VCs released by soilborne fungi Fusarium oxysporum and Verticillium dahliae affect Arabidopsis thaliana responses to abiotic and biotic stresses. Under salt stress, VCs from both fungi helped its growth and increased chlorophyll content. However, in contrast to wild-type A. thaliana (Col-0), V. dahliae VCs failed to increase leaf surface area in auxin signalling mutants aux1-7, tir1-1 and axr1-3. Compared to wild-type Col-0, the degree of lateral root density enhanced by V. dahliae VCs in these mutants was also reduced. Consistent with the involvement of auxin signalling in fungal VC-mediated salt torelance, A. thaliana line carrying DR5::GUS displayed increased auxin accumulation in root apex upon exposure to V. dahliae VCs, and 1-naphthylphthalamic acid, an auxin transport inhibitor, adversely affected V. dahliae VC-mediated salt tolerance. F. oxysporum VCs induced the expression of PR1 but not PDF1.2 in A. thaliana lines containing PR1::GUS and PFD1.2::GUS. When challenged with Pseudomonas syringae after the exposure to F. oxysporum VCs, A. thaliana showed reduced disease symptoms. However, the number of bacterial cells in F. oxysporum VC-treated plants was not significantly different from that in control plants.
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