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Maize miRNA and target regulation in response to hormone depletion and light exposure during somatic embryogenesis.

Chávez-Hernández EC, Alejandri-Ramírez ND, Juárez-González VT, Dinkova TD - Front Plant Sci (2015)

Bottom Line: Stress-related miRNA targets showed greater differences between cultivars than development-related targets. miRNA/target inverse relationship was more frequently observed in darkness than light.Overall our results demonstrate that hormone depletion exerts a great influence on specific miRNA expression during plant regeneration independently of light.The reproducibility or differences observed for particular miRNA-target regulation between two different highly embryogenic genotypes provide clues for conserved miRNA roles within the SE process.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México Mexico City, Mexico.

ABSTRACT
Maize somatic embryogenesis (SE) is induced from the immature zygotic embryo in darkness and under the appropriate hormones' levels. Small RNA expression is reprogrammed and certain miRNAs become particularly enriched during induction while others, characteristic to the zygotic embryo, decrease. To explore the impact of different environmental cues on miRNA regulation in maize SE, we tested specific miRNA abundance and their target gene expression in response to photoperiod and hormone depletion for two different maize cultivars (VS-535 and H-565). The expression levels of miR156, miR159, miR164, miR168, miR397, miR398, miR408, miR528, and some predicted targets (SBP23, GA-MYB, CUC2, AGO1c, LAC2, SOD9, GR1, SOD1A, PLC) were examined upon staged hormone depletion in the presence of light photoperiod or darkness. Almost all examined miRNA, except miR159, increased upon hormone depletion, regardless photoperiod absence/presence. miR528, miR408, and miR398 changed the most. On the other hand, expression of miRNA target genes was strongly regulated by the photoperiod exposure. Stress-related miRNA targets showed greater differences between cultivars than development-related targets. miRNA/target inverse relationship was more frequently observed in darkness than light. Interestingly, miR528, but not miR159, miR168 or miR398, was located on polyribosome fractions suggesting a role for this miRNA at the level of translation. Overall our results demonstrate that hormone depletion exerts a great influence on specific miRNA expression during plant regeneration independently of light. However, their targets are additionally influenced by the presence of photoperiod. The reproducibility or differences observed for particular miRNA-target regulation between two different highly embryogenic genotypes provide clues for conserved miRNA roles within the SE process.

No MeSH data available.


Related in: MedlinePlus

The abundance of stress-related miRNA targets is dependent on the genotype during maize plant regeneration through SE. Transcript levels of miRNA stress-related targets were analyzed by qRT-PCR in the same samples as miRNAs for VS-535 (A) and H-565 (B). The18S rRNA was used as reference control and plotted values represent the expression of each mRNA relative to 100% hormones (a, set to 1). Fold changes are shown accordingly for 50% hormones (b, d); 0% hormones (c, e) and plantlet (f). Filled bars represent darkness and empty bars, photoperiod. The corresponding miRNA Northern blots are shown at the top of each chart. miR397 target: GRMZM2G146152_T01 (LAC2); miR398 target: GRMZM2G058522_T01 (SOD9); miR408 target: GRMZM2G384327_T03 (GR1); miR528 targets: GRMZM2G106928_T01 (SOD1A) and GRMZM2G107562_T01 (PLC). Error bars represent + Standard Error; n = 6. Statistically significant differences were identified using Two-Way ANOVA and Tukey as described in Methods at *P < 0.05.
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Figure 4: The abundance of stress-related miRNA targets is dependent on the genotype during maize plant regeneration through SE. Transcript levels of miRNA stress-related targets were analyzed by qRT-PCR in the same samples as miRNAs for VS-535 (A) and H-565 (B). The18S rRNA was used as reference control and plotted values represent the expression of each mRNA relative to 100% hormones (a, set to 1). Fold changes are shown accordingly for 50% hormones (b, d); 0% hormones (c, e) and plantlet (f). Filled bars represent darkness and empty bars, photoperiod. The corresponding miRNA Northern blots are shown at the top of each chart. miR397 target: GRMZM2G146152_T01 (LAC2); miR398 target: GRMZM2G058522_T01 (SOD9); miR408 target: GRMZM2G384327_T03 (GR1); miR528 targets: GRMZM2G106928_T01 (SOD1A) and GRMZM2G107562_T01 (PLC). Error bars represent + Standard Error; n = 6. Statistically significant differences were identified using Two-Way ANOVA and Tukey as described in Methods at *P < 0.05.

Mentions: Several of the miRNA targets analyzed in this study (SBP23, GAMYB, CUC2) encode for transcription factors known to participate in plant developmental switches including zygotic embryogenesis (Table 1). Others represent enzymes involved in plant stress response (targets of miR397, miR398, miR408, miR528) or the miRNA biogenesis pathway itself (miR168). According to this, we separated the results from qRT-PCR in development-related and stress-related miRNA targets (Figures 3, 4). The levels of GRMZM2G039455_T01, an AGO-like transcript also termed AGO117 or AGO1c (Qian et al., 2011) were considered within the development-related targets, but according to its proposed function in miRNA biogenesis it actually corresponds to any of the subdivisions.


Maize miRNA and target regulation in response to hormone depletion and light exposure during somatic embryogenesis.

Chávez-Hernández EC, Alejandri-Ramírez ND, Juárez-González VT, Dinkova TD - Front Plant Sci (2015)

The abundance of stress-related miRNA targets is dependent on the genotype during maize plant regeneration through SE. Transcript levels of miRNA stress-related targets were analyzed by qRT-PCR in the same samples as miRNAs for VS-535 (A) and H-565 (B). The18S rRNA was used as reference control and plotted values represent the expression of each mRNA relative to 100% hormones (a, set to 1). Fold changes are shown accordingly for 50% hormones (b, d); 0% hormones (c, e) and plantlet (f). Filled bars represent darkness and empty bars, photoperiod. The corresponding miRNA Northern blots are shown at the top of each chart. miR397 target: GRMZM2G146152_T01 (LAC2); miR398 target: GRMZM2G058522_T01 (SOD9); miR408 target: GRMZM2G384327_T03 (GR1); miR528 targets: GRMZM2G106928_T01 (SOD1A) and GRMZM2G107562_T01 (PLC). Error bars represent + Standard Error; n = 6. Statistically significant differences were identified using Two-Way ANOVA and Tukey as described in Methods at *P < 0.05.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4510349&req=5

Figure 4: The abundance of stress-related miRNA targets is dependent on the genotype during maize plant regeneration through SE. Transcript levels of miRNA stress-related targets were analyzed by qRT-PCR in the same samples as miRNAs for VS-535 (A) and H-565 (B). The18S rRNA was used as reference control and plotted values represent the expression of each mRNA relative to 100% hormones (a, set to 1). Fold changes are shown accordingly for 50% hormones (b, d); 0% hormones (c, e) and plantlet (f). Filled bars represent darkness and empty bars, photoperiod. The corresponding miRNA Northern blots are shown at the top of each chart. miR397 target: GRMZM2G146152_T01 (LAC2); miR398 target: GRMZM2G058522_T01 (SOD9); miR408 target: GRMZM2G384327_T03 (GR1); miR528 targets: GRMZM2G106928_T01 (SOD1A) and GRMZM2G107562_T01 (PLC). Error bars represent + Standard Error; n = 6. Statistically significant differences were identified using Two-Way ANOVA and Tukey as described in Methods at *P < 0.05.
Mentions: Several of the miRNA targets analyzed in this study (SBP23, GAMYB, CUC2) encode for transcription factors known to participate in plant developmental switches including zygotic embryogenesis (Table 1). Others represent enzymes involved in plant stress response (targets of miR397, miR398, miR408, miR528) or the miRNA biogenesis pathway itself (miR168). According to this, we separated the results from qRT-PCR in development-related and stress-related miRNA targets (Figures 3, 4). The levels of GRMZM2G039455_T01, an AGO-like transcript also termed AGO117 or AGO1c (Qian et al., 2011) were considered within the development-related targets, but according to its proposed function in miRNA biogenesis it actually corresponds to any of the subdivisions.

Bottom Line: Stress-related miRNA targets showed greater differences between cultivars than development-related targets. miRNA/target inverse relationship was more frequently observed in darkness than light.Overall our results demonstrate that hormone depletion exerts a great influence on specific miRNA expression during plant regeneration independently of light.The reproducibility or differences observed for particular miRNA-target regulation between two different highly embryogenic genotypes provide clues for conserved miRNA roles within the SE process.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México Mexico City, Mexico.

ABSTRACT
Maize somatic embryogenesis (SE) is induced from the immature zygotic embryo in darkness and under the appropriate hormones' levels. Small RNA expression is reprogrammed and certain miRNAs become particularly enriched during induction while others, characteristic to the zygotic embryo, decrease. To explore the impact of different environmental cues on miRNA regulation in maize SE, we tested specific miRNA abundance and their target gene expression in response to photoperiod and hormone depletion for two different maize cultivars (VS-535 and H-565). The expression levels of miR156, miR159, miR164, miR168, miR397, miR398, miR408, miR528, and some predicted targets (SBP23, GA-MYB, CUC2, AGO1c, LAC2, SOD9, GR1, SOD1A, PLC) were examined upon staged hormone depletion in the presence of light photoperiod or darkness. Almost all examined miRNA, except miR159, increased upon hormone depletion, regardless photoperiod absence/presence. miR528, miR408, and miR398 changed the most. On the other hand, expression of miRNA target genes was strongly regulated by the photoperiod exposure. Stress-related miRNA targets showed greater differences between cultivars than development-related targets. miRNA/target inverse relationship was more frequently observed in darkness than light. Interestingly, miR528, but not miR159, miR168 or miR398, was located on polyribosome fractions suggesting a role for this miRNA at the level of translation. Overall our results demonstrate that hormone depletion exerts a great influence on specific miRNA expression during plant regeneration independently of light. However, their targets are additionally influenced by the presence of photoperiod. The reproducibility or differences observed for particular miRNA-target regulation between two different highly embryogenic genotypes provide clues for conserved miRNA roles within the SE process.

No MeSH data available.


Related in: MedlinePlus