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Multiple roles of the transcription factor AtMYBR1/AtMYB44 in ABA signaling, stress responses, and leaf senescence.

Jaradat MR, Feurtado JA, Huang D, Lu Y, Cutler AJ - BMC Plant Biol. (2013)

Bottom Line: MYBR1 appears to exhibit partially redundant functions with AtMYBR2 (MYB77) and double mybr1 X mybr2 mutants exhibited stronger senescence and stress related phenotypes than single mybr1 and mybr2 mutants.MYBR1 is a negative regulator of ABA, stress, wounding responses and blocks senescence.It appears to have a homeostatic function to maintain growth processes in the event of physical damage or stress.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Biotechnology Institute, National Research Council of Canada, 110 Gymnasium Place, Saskatoon S7N 0W9, Canada. adrian.cutler@nrc-cnrc.gc.ca.

ABSTRACT

Background: The transcription factor AtMYBR1 (MYB44) is a member of the MYB family of transcription factors and is expressed throughout the plant life cycle and especially in senescing and wounded leaves. It has previously been shown to be involved in responses to abiotic stress and is regulated by phosphorylation.

Results: When MYBR1 was over-expressed under the control of the constitutive 35S promoter in Arabidopsis thaliana (OxMYBR1), leaf senescence was delayed. In contrast loss-of-function mybr1 plants showed more rapid chlorophyll loss and senescence. The MYBR1 promoter strongly drove β-GLUCURONIDASE reporter gene expression in tissues immediately after wounding and many wounding/pathogenesis genes were downregulated in OxMYBR1. OxMYBR1 plants were more susceptible to injury under water stress than wildtype, which was correlated with suppression of many ABA inducible stress genes in OxMYBR1. Conversely, mybr1 plants were more tolerant of water stress and exhibited reduced rates of water loss from leaves. MYBR1 physically interacted with ABA receptor PYR1-LIKE8 (PYL8) suggesting a direct involvement of MYBR1 in early ABA signaling. MYBR1 appears to exhibit partially redundant functions with AtMYBR2 (MYB77) and double mybr1 X mybr2 mutants exhibited stronger senescence and stress related phenotypes than single mybr1 and mybr2 mutants.

Conclusions: MYBR1 is a negative regulator of ABA, stress, wounding responses and blocks senescence. It appears to have a homeostatic function to maintain growth processes in the event of physical damage or stress.

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Related in: MedlinePlus

Primary root lengths of MYBR1 genotypes. Primary roots were measured in soil-grown 8 day old plants. The results are expressed as the percentage of roots of each genotype that fell within the four indicated length ranges. For each genotype, the total number of measured roots and the total range of lengths in cm were: OxMYBR1 42–6, 380 (range 0.54-2.12); OxMYBR1 31–3, 203 (range 0.71-2.71); Wild type, 270 (range 0.62-3.57); mybr1, 372 (range 1.22-3.59).
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Figure 8: Primary root lengths of MYBR1 genotypes. Primary roots were measured in soil-grown 8 day old plants. The results are expressed as the percentage of roots of each genotype that fell within the four indicated length ranges. For each genotype, the total number of measured roots and the total range of lengths in cm were: OxMYBR1 42–6, 380 (range 0.54-2.12); OxMYBR1 31–3, 203 (range 0.71-2.71); Wild type, 270 (range 0.62-3.57); mybr1, 372 (range 1.22-3.59).

Mentions: We examined the roots of gain-and loss of MYBR1 function genotypes (Figure 8). Primary roots of OxMYBR1 lines were drastically shorter, whereas those of mybr1 were notably longer relative to WT. This shorter root phenotype of OxMYBR1 may contribute toward reduced water uptake in the OxMYBR1 lines as noted earlier, and may help explain the differences between results of PEG treatments and soil drying experiments described above.


Multiple roles of the transcription factor AtMYBR1/AtMYB44 in ABA signaling, stress responses, and leaf senescence.

Jaradat MR, Feurtado JA, Huang D, Lu Y, Cutler AJ - BMC Plant Biol. (2013)

Primary root lengths of MYBR1 genotypes. Primary roots were measured in soil-grown 8 day old plants. The results are expressed as the percentage of roots of each genotype that fell within the four indicated length ranges. For each genotype, the total number of measured roots and the total range of lengths in cm were: OxMYBR1 42–6, 380 (range 0.54-2.12); OxMYBR1 31–3, 203 (range 0.71-2.71); Wild type, 270 (range 0.62-3.57); mybr1, 372 (range 1.22-3.59).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4219380&req=5

Figure 8: Primary root lengths of MYBR1 genotypes. Primary roots were measured in soil-grown 8 day old plants. The results are expressed as the percentage of roots of each genotype that fell within the four indicated length ranges. For each genotype, the total number of measured roots and the total range of lengths in cm were: OxMYBR1 42–6, 380 (range 0.54-2.12); OxMYBR1 31–3, 203 (range 0.71-2.71); Wild type, 270 (range 0.62-3.57); mybr1, 372 (range 1.22-3.59).
Mentions: We examined the roots of gain-and loss of MYBR1 function genotypes (Figure 8). Primary roots of OxMYBR1 lines were drastically shorter, whereas those of mybr1 were notably longer relative to WT. This shorter root phenotype of OxMYBR1 may contribute toward reduced water uptake in the OxMYBR1 lines as noted earlier, and may help explain the differences between results of PEG treatments and soil drying experiments described above.

Bottom Line: MYBR1 appears to exhibit partially redundant functions with AtMYBR2 (MYB77) and double mybr1 X mybr2 mutants exhibited stronger senescence and stress related phenotypes than single mybr1 and mybr2 mutants.MYBR1 is a negative regulator of ABA, stress, wounding responses and blocks senescence.It appears to have a homeostatic function to maintain growth processes in the event of physical damage or stress.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Biotechnology Institute, National Research Council of Canada, 110 Gymnasium Place, Saskatoon S7N 0W9, Canada. adrian.cutler@nrc-cnrc.gc.ca.

ABSTRACT

Background: The transcription factor AtMYBR1 (MYB44) is a member of the MYB family of transcription factors and is expressed throughout the plant life cycle and especially in senescing and wounded leaves. It has previously been shown to be involved in responses to abiotic stress and is regulated by phosphorylation.

Results: When MYBR1 was over-expressed under the control of the constitutive 35S promoter in Arabidopsis thaliana (OxMYBR1), leaf senescence was delayed. In contrast loss-of-function mybr1 plants showed more rapid chlorophyll loss and senescence. The MYBR1 promoter strongly drove β-GLUCURONIDASE reporter gene expression in tissues immediately after wounding and many wounding/pathogenesis genes were downregulated in OxMYBR1. OxMYBR1 plants were more susceptible to injury under water stress than wildtype, which was correlated with suppression of many ABA inducible stress genes in OxMYBR1. Conversely, mybr1 plants were more tolerant of water stress and exhibited reduced rates of water loss from leaves. MYBR1 physically interacted with ABA receptor PYR1-LIKE8 (PYL8) suggesting a direct involvement of MYBR1 in early ABA signaling. MYBR1 appears to exhibit partially redundant functions with AtMYBR2 (MYB77) and double mybr1 X mybr2 mutants exhibited stronger senescence and stress related phenotypes than single mybr1 and mybr2 mutants.

Conclusions: MYBR1 is a negative regulator of ABA, stress, wounding responses and blocks senescence. It appears to have a homeostatic function to maintain growth processes in the event of physical damage or stress.

Show MeSH
Related in: MedlinePlus