Spectral-dependence of light-inhibited hypocotyl elongation in photomorphogenic mutants ofArabidopsis: evidence for a UV-A photosensor

CBL-interacting protein kinase (CIPK) family is a unique group of serine/threonine protein kinase family identified in plants. Among this family, AtCIPK23 and its homologs in some plants are taken as a notable group for their importance in ions transport and stress responses. However, there are limited reports on their roles in seedling growth and development, especially in Solanaceae plants. In this study, NtCIPK23, a homolog of AtCIPK23 was cloned from Nicotiana tabacum. Expression analysis showed that NtCIPK23 is mainly expressed in the radicle, hypocotyl, and cotyledons of young tobacco seedlings. The transcriptional level of NtCIPK23 changes rapidly and spatiotemporally during seed germination and early seedling growth. To study the biological function of NtCIPK23 at these stages, the overexpressing and CRISPR/Cas9-mediated knock-out (ntcipk23) tobacco lines were generated. Phenotype analysis indicated that knock-out of NtCIPK23 significantly delays seed germination and the appearance of green cotyledon of young tobacco seedling. Overexpression of NtCIPK23 promotes cotyledon expansion and hypocotyl elongation of young tobacco seedlings. The expression of NtCIPK23 in hypocotyl is strongly upregulated by darkness and inhibited under light, suggesting that a regulatory mechanism of light might underlie. Consistently, a more obvious difference in hypocotyl length among different tobacco materials was observed in the dark, compared to that under the light, indicating that the upregulation of NtCIPK23 contributes greatly to the hypocotyl elongation. Taken together, NtCIPK23 not only enhances tobacco seed germination, but also accelerate early seedling growth by promoting cotyledon greening rate, cotyledon expansion and hypocotyl elongation of young tobacco seedlings.

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Guard cells control hypocotyl elongation through HXK1, HY5, and PIF4

Communications Biology ◽

10.1038/s42003-021-02283-y ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Gilor Kelly ◽

Danja Brandsma ◽

Aiman Egbaria ◽

Ofer Stein ◽

Adi Doron-Faigenboim ◽

...

Keyword(s):

Transcription Factors ◽

Blue Light ◽

Opposite Effect ◽

Red Light ◽

Guard Cells ◽

Cell Types ◽

Hypocotyl Elongation ◽

Sugar Production ◽

Effect Of Light

AbstractThe hypocotyls of germinating seedlings elongate in a search for light to enable autotrophic sugar production. Upon exposure to light, photoreceptors that are activated by blue and red light halt elongation by preventing the degradation of the hypocotyl-elongation inhibitor HY5 and by inhibiting the activity of the elongation-promoting transcription factors PIFs. The question of how sugar affects hypocotyl elongation and which cell types stimulate and stop that elongation remains unresolved. We found that overexpression of a sugar sensor, Arabidopsis hexokinase 1 (HXK1), in guard cells promotes hypocotyl elongation under white and blue light through PIF4. Furthermore, expression of PIF4 in guard cells is sufficient to promote hypocotyl elongation in the light, while expression of HY5 in guard cells is sufficient to inhibit the elongation of the hy5 mutant and the elongation stimulated by HXK1. HY5 exits the guard cells and inhibits hypocotyl elongation, but is degraded in the dark. We also show that the inhibition of hypocotyl elongation by guard cells’ HY5 involves auto-activation of HY5 expression in other tissues. It appears that guard cells are capable of coordinating hypocotyl elongation and that sugar and HXK1 have the opposite effect of light on hypocotyl elongation, converging at PIF4.

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HsfA1d promotes hypocotyl elongation under chilling via enhancing expression of ribosomal protein genes in Arabidopsis

New Phytologist ◽

10.1111/nph.17413 ◽

2021 ◽

Author(s):

Huimin Liu ◽

Yan Zhang ◽

Shan Lu ◽

Hao Chen ◽

Jiawen Wu ◽

...

Keyword(s):

Ribosomal Protein ◽

Hypocotyl Elongation ◽

Ribosomal Protein Genes

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THE BAND GAP ESTIMATION OF ZINC MANGANESE PHOSPHATE GLASSES

Modern Physics Letters B ◽

10.1142/s0217984908015255 ◽

2008 ◽

Vol 22 (12) ◽

pp. 1265-1272 ◽

Cited By ~ 1

Author(s):

S. A. SIDDIQI ◽

M. A. GHAURI ◽

M. J. S. BAIG

Keyword(s):

Electric Fields ◽

Spectral Dependence ◽

Transport Mechanism ◽

Phosphate Glasses ◽

Band Gaps ◽

Spectral Energy ◽

Charge Transport Mechanism ◽

Optical Band Gaps ◽

Manganese Phosphate ◽

Made In

Zinc manganese phosphate glasses ( ZnO - MnO - P 2 O 5) of different compositions are synthesized. The optical band gaps are measured in the UV-VIS region. Photoconduction measurements are also made in the spectral energy range 1.5–6.2 eV. At various applied electric fields, the values of the energy band gaps have been deduced from the spectral dependence curves. Furthermore, the band gaps at zero applied voltage were also obtained for different compositions. The charge transport mechanism in these glasses is studied under the Mott's model.

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