WUSCHEL-Related Homeobox Genes Cooperate with Cytokinin Signalling to Promote Bulbil Formation in Lilium lancifolium

The bulbil is an important vegetative reproductive organ in triploid Lilium lancifolium. Based on our previously obtained transcriptome data, we screened two WUSCHCEL-related homeobox (WOX) genes closely related to bulbil formation, LlWOX9 and LlWOX11. However, the biological functions and regulatory mechanisms of LlWOX9 and LlWOX11 are unclear. In this study, we cloned the full-length coding sequences of LlWOX9 and LlWOX11. Transgenic Arabidopsis showed increased branch numbers, and the overexpression of LlWOX9 and LlWOX11 in stem segments promoted bulbil formation, while the silencing of LlWOX9 and LlWOX11 inhibited bulbil formation, indicating that LlWOX9 and LlWOX11 are positive regulators of bulbil formation. Cytokinins acting through type-B response regulators (type-B RRs) could bind to the promoters of LlWOX9 and LlWOX11 and promote their transcription. LlWOX11 could enhance cytokinin pathway signalling by inhibiting the transcription of type-A LlRR9. Our study enriches the understanding of the regulation of plant development by the WOX gene family and lays a foundation for further research on the molecular mechanism of bulbil formation in lily.

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Cytokinin Type-B Response Regulators Promote Bulbil Initiation in Lilium lancifolium

International Journal of Molecular Sciences ◽

10.3390/ijms22073320 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3320

Author(s):

Guoren He ◽

Panpan Yang ◽

Yuwei Cao ◽

Yuchao Tang ◽

Ling Wang ◽

...

Keyword(s):

Gene Expression ◽

Amino Acids ◽

Reproductive Organ ◽

Plant Tissues ◽

Axillary Meristem ◽

Type B ◽

Response Regulators ◽

N Terminus ◽

Lilium Lancifolium ◽

First Time

The bulbil is an important vegetative reproductive organ in triploid Lilium lancifolium whose development is promoted by cytokinins. Type-B response regulators (RRs) are critical regulators that mediate primary cytokinin responses and promote cytokinin-induced gene expression. However, the function of cytokinin type-B Arabidopsis RRs (ARRs) in regulating bulbil formation is unclear. In this study, we identified five type-B LlRRs, LlRR1, LlRR2, LlRR10, LlRR11 and LlRR12, in L. lancifolium for the first time. The five LlRRs encode proteins of 715, 675, 573, 582 and 647 amino acids. All of the regulators belong to the B-I subfamily, whose members typically contain a conserved CheY-homologous receiver (REC) domain and an Myb DNA-binding (MYB) domain at the N-terminus. As transcription factors, all five type-B LlRRs localize at the nucleus and are widely expressed in plant tissues, especially during axillary meristem (AM) formation. Functional analysis showed that type-B LlRRs are involved in bulbil formation in a functionally redundant manner and can activate LlRR9 expression. In summary, our study elucidates the process by which cytokinins regulate bulbil initiation in L. lancifolium through type-B LlRRs and lays a foundation for research on the molecular mechanism of bulbil formation in the lily.

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NMR Solution Structure of B-Motif, a Signature Motif of Type-B Response Regulators for His-to-Asp Phosphorelay Signal Transduction System, and Its Interactions with DNA

Peptides: The Wave of the Future ◽

10.1007/978-94-010-0464-0_190 ◽

2001 ◽

pp. 411-412

Author(s):

Kazuo Hosoda ◽

Etsuko Katoh ◽

Tomohisa Hatta ◽

Takeshi Mizuno ◽

Toshimasa Yamazaki

Keyword(s):

Signal Transduction ◽

Solution Structure ◽

Type B ◽

Response Regulators ◽

Signal Transduction System ◽

Nmr Solution Structure ◽

Signature Motif

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Type-B ARABIDOPSIS RESPONSE REGULATORs Specify the Shoot Stem Cell Niche by Dual Regulation of WUSCHEL

The Plant Cell ◽

10.1105/tpc.16.00640 ◽

2017 ◽

Vol 29 (6) ◽

pp. 1357-1372 ◽

Cited By ~ 82

Author(s):

Wen Jing Meng ◽

Zhi Juan Cheng ◽

Ya Lin Sang ◽

Miao Miao Zhang ◽

Xiao Fei Rong ◽

...

Keyword(s):

Stem Cell ◽

Stem Cell Niche ◽

Type B ◽

Response Regulators ◽

Cell Niche

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Type-B ARABIDOPSIS RESPONSE REGULATORs Directly Activate WUSCHEL

Trends in Plant Science ◽

10.1016/j.tplants.2017.08.007 ◽

2017 ◽

Vol 22 (10) ◽

pp. 815-817 ◽

Cited By ~ 10

Author(s):

Fei Zhang ◽

Alan May ◽

Vivian F. Irish

Keyword(s):

Type B ◽

Response Regulators

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Arabidopsis type B cytokinin response regulators ARR1, ARR10, and ARR12 negatively regulate plant responses to drought

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1600399113 ◽

2016 ◽

Vol 113 (11) ◽

pp. 3090-3095 ◽

Cited By ~ 75

Author(s):

Kien Huu Nguyen ◽

Chien Van Ha ◽

Rie Nishiyama ◽

Yasuko Watanabe ◽

Marco Antonio Leyva-González ◽

...

Keyword(s):

Drought Tolerance ◽

Anthocyanin Biosynthesis ◽

Stomatal Density ◽

Control Plant ◽

Membrane Integrity ◽

Plant Responses ◽

Type B ◽

Response Regulators ◽

Triple Mutant ◽

Critical Function

In this study, we used a loss-of-function approach to elucidate the functions of three Arabidopsis type B response regulators (ARRs)—namely ARR1, ARR10, and ARR12—in regulating the Arabidopsis plant responses to drought. The arr1,10,12 triple mutant showed a significant increase in drought tolerance versus WT plants, as indicated by its higher relative water content and survival rate on drying soil. This enhanced drought tolerance of arr1,10,12 plants can be attributed to enhanced cell membrane integrity, increased anthocyanin biosynthesis, abscisic acid (ABA) hypersensitivity, and reduced stomatal aperture, but not to altered stomatal density. Further drought-tolerance tests of lower-order double and single mutants indicated that ARR1, ARR10, and ARR12 negatively and redundantly control plant responses to drought, with ARR1 appearing to bear the most critical function among the three proteins. In agreement with these findings, a comparative genome-wide analysis of the leaves of arr1,10,12 and WT plants under both normal and dehydration conditions suggested a cytokinin (CK) signaling-mediated network controlling plant adaptation to drought via many dehydration/drought- and/or ABA-responsive genes that can provide osmotic adjustment and protection to cellular and membrane structures. Expression of all three ARR genes was repressed by dehydration and ABA treatments, inferring that plants down-regulate these genes as an adaptive mechanism to survive drought. Collectively, our results demonstrate that repression of CK response, and thus CK signaling, is one of the strategies plants use to cope with water deficit, providing novel insight for the design of drought-tolerant plants by genetic engineering.

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