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MADS-box transcription factor AGL21 regulates lateral root development and responds to multiple external and physiological signals.

Yu LH, Miao ZQ, Qi GF, Wu J, Cai XT, Mao JL, Xiang CB - Mol Plant (2014)

Bottom Line: AGL21 was induced by many plant hormones and environmental stresses, suggesting a function of this gene in root system plasticity in response to various signals.Furthermore, AGL21 was found positively regulating auxin accumulation in lateral root primordia and lateral roots by enhancing local auxin biosynthesis, thus stimulating lateral root initiation and growth.We propose that AGL21 may be involved in various environmental and physiological signals-mediated lateral root development and growth.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China.

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AGL21 Expression Is Regulated by Hormones.(A–C) qRT–PCR analyses of AGL21 expression in wild-type seedlings during the time course after IAA (A), MeJA (B), or ABA (C) treatment. Eight-day-old Col-0 seedlings were incubated in MS liquid cultures with 10 μM IAA, 50 μM MeJA, and 20 μM ABA, respectively, and whole seedlings were harvested at indicated time points for RNA extraction and qRT–PCR analyses. The transcript levels of AGL21 were normalized to the UBQ5 expression. Values are mean ± SD and asterisks denote Student’s t-test significance compared with untreated plants: * P < 0.05; ** P < 0.01; *** P < 0.001.(D, E) IAA, MeJA, and ABA-induced pAGL21::GUS expression in the primary root (D), LRP, and LR (E). Seven-day-old seedlings of pAGL21::GUS transgenic line grown on MS agar medium were transferred either to hormone-free MS agar medium or to MS agar medium supplemented with 10 μM IAA, 10 μM MeJA, or 10 μM ABA for 1 d, respectively. The seedlings were harvested for GUS staining for 8h.
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Figure 4: AGL21 Expression Is Regulated by Hormones.(A–C) qRT–PCR analyses of AGL21 expression in wild-type seedlings during the time course after IAA (A), MeJA (B), or ABA (C) treatment. Eight-day-old Col-0 seedlings were incubated in MS liquid cultures with 10 μM IAA, 50 μM MeJA, and 20 μM ABA, respectively, and whole seedlings were harvested at indicated time points for RNA extraction and qRT–PCR analyses. The transcript levels of AGL21 were normalized to the UBQ5 expression. Values are mean ± SD and asterisks denote Student’s t-test significance compared with untreated plants: * P < 0.05; ** P < 0.01; *** P < 0.001.(D, E) IAA, MeJA, and ABA-induced pAGL21::GUS expression in the primary root (D), LRP, and LR (E). Seven-day-old seedlings of pAGL21::GUS transgenic line grown on MS agar medium were transferred either to hormone-free MS agar medium or to MS agar medium supplemented with 10 μM IAA, 10 μM MeJA, or 10 μM ABA for 1 d, respectively. The seedlings were harvested for GUS staining for 8h.

Mentions: Several types of cis-acting elements, including auxin response element (AuxRE), ABA response element like (ABRE-like), G-box, GCC-box like, and JA-responsive cis-element (JARE) were found in the AGL21 promoter (Supplemental Figure 2), implicating that AGL21 could respond to various plant hormones and environmental stresses. We thus performed qRT–PCR to test this. The results showed that the expression of AGL21 was indeed up-regulated by IAA, MeJA, and ABA (Figure 4A–4C). To confirm these results, we treated the pAGL21::GUS reporter line with IAA, MeJA, and ABA. GUS staining showed that IAA and MeJA clearly induced the expression of AGL21 in the meristematic and elongation zones of PRs (Figure 4D). IAA and MeJA could enhance the expression of AGL21 in early stages of LPRs and emerged LRs and even the later stages of LRPs, where it was not expressed without hormone treatments (Figure 4E). The response of AGL21 expression to IAA was particularly intense in LRPs (Supplemental Figure 3). Interestingly, ABA could induce AGL21 expression in the PR tips, meristematic zone, and elongation zone (Figure 4D). However, in the middle and upper differentiation zone, GUS activity was diminished (Figure 4E). It should be noted that, in roots, AGL21 was preferentially enhanced by IAA and MeJA in the central cylinder, root tips, and LRPs.


MADS-box transcription factor AGL21 regulates lateral root development and responds to multiple external and physiological signals.

Yu LH, Miao ZQ, Qi GF, Wu J, Cai XT, Mao JL, Xiang CB - Mol Plant (2014)

AGL21 Expression Is Regulated by Hormones.(A–C) qRT–PCR analyses of AGL21 expression in wild-type seedlings during the time course after IAA (A), MeJA (B), or ABA (C) treatment. Eight-day-old Col-0 seedlings were incubated in MS liquid cultures with 10 μM IAA, 50 μM MeJA, and 20 μM ABA, respectively, and whole seedlings were harvested at indicated time points for RNA extraction and qRT–PCR analyses. The transcript levels of AGL21 were normalized to the UBQ5 expression. Values are mean ± SD and asterisks denote Student’s t-test significance compared with untreated plants: * P < 0.05; ** P < 0.01; *** P < 0.001.(D, E) IAA, MeJA, and ABA-induced pAGL21::GUS expression in the primary root (D), LRP, and LR (E). Seven-day-old seedlings of pAGL21::GUS transgenic line grown on MS agar medium were transferred either to hormone-free MS agar medium or to MS agar medium supplemented with 10 μM IAA, 10 μM MeJA, or 10 μM ABA for 1 d, respectively. The seedlings were harvested for GUS staining for 8h.
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Figure 4: AGL21 Expression Is Regulated by Hormones.(A–C) qRT–PCR analyses of AGL21 expression in wild-type seedlings during the time course after IAA (A), MeJA (B), or ABA (C) treatment. Eight-day-old Col-0 seedlings were incubated in MS liquid cultures with 10 μM IAA, 50 μM MeJA, and 20 μM ABA, respectively, and whole seedlings were harvested at indicated time points for RNA extraction and qRT–PCR analyses. The transcript levels of AGL21 were normalized to the UBQ5 expression. Values are mean ± SD and asterisks denote Student’s t-test significance compared with untreated plants: * P < 0.05; ** P < 0.01; *** P < 0.001.(D, E) IAA, MeJA, and ABA-induced pAGL21::GUS expression in the primary root (D), LRP, and LR (E). Seven-day-old seedlings of pAGL21::GUS transgenic line grown on MS agar medium were transferred either to hormone-free MS agar medium or to MS agar medium supplemented with 10 μM IAA, 10 μM MeJA, or 10 μM ABA for 1 d, respectively. The seedlings were harvested for GUS staining for 8h.
Mentions: Several types of cis-acting elements, including auxin response element (AuxRE), ABA response element like (ABRE-like), G-box, GCC-box like, and JA-responsive cis-element (JARE) were found in the AGL21 promoter (Supplemental Figure 2), implicating that AGL21 could respond to various plant hormones and environmental stresses. We thus performed qRT–PCR to test this. The results showed that the expression of AGL21 was indeed up-regulated by IAA, MeJA, and ABA (Figure 4A–4C). To confirm these results, we treated the pAGL21::GUS reporter line with IAA, MeJA, and ABA. GUS staining showed that IAA and MeJA clearly induced the expression of AGL21 in the meristematic and elongation zones of PRs (Figure 4D). IAA and MeJA could enhance the expression of AGL21 in early stages of LPRs and emerged LRs and even the later stages of LRPs, where it was not expressed without hormone treatments (Figure 4E). The response of AGL21 expression to IAA was particularly intense in LRPs (Supplemental Figure 3). Interestingly, ABA could induce AGL21 expression in the PR tips, meristematic zone, and elongation zone (Figure 4D). However, in the middle and upper differentiation zone, GUS activity was diminished (Figure 4E). It should be noted that, in roots, AGL21 was preferentially enhanced by IAA and MeJA in the central cylinder, root tips, and LRPs.

Bottom Line: AGL21 was induced by many plant hormones and environmental stresses, suggesting a function of this gene in root system plasticity in response to various signals.Furthermore, AGL21 was found positively regulating auxin accumulation in lateral root primordia and lateral roots by enhancing local auxin biosynthesis, thus stimulating lateral root initiation and growth.We propose that AGL21 may be involved in various environmental and physiological signals-mediated lateral root development and growth.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province 230027, China.

Show MeSH
Related in: MedlinePlus