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Brassinosteroids suppress ethylene-induced fruitlet abscission through LcBZR1/2-mediated transcriptional repression of LcACS1/4 and LcACO2/3 in litchi
Abscission in plants is tightly controlled by multiple phytohormones and the expression of various genes. However, whether the plant hormone brassinosteroids (BRs) are involved in this process is largely unknown. Here, we found that exogenous application of BRs reduced the ethylene-induced fruitlet...
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Published in: | Horticulture research 2021-05, Vol.8 (1) |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Abscission in plants is tightly controlled by multiple phytohormones and the expression of various genes. However, whether the plant hormone brassinosteroids (BRs) are involved in this process is largely unknown. Here, we found that exogenous application of BRs reduced the ethylene-induced fruitlet abscission of litchi due to lower ethylene (ET) production and suppressed the expression of the ethylene biosynthetic genes
LcACS1
/
4
and
LcACO2
/
3
in the fruitlet abscission zone (FAZ). Two genes that encode the BR core signaling components brassinazole resistant (BZR) proteins, namely,
LcBZR1
and
LcBZR2
, were characterized. LcBZR1/2 were localized to the nucleus and acted as transcription repressors. Interestingly, the
LcBZR1
/
2
transcript levels were not changed during ET-induced fruitlet abscission, while their expression levels were significantly increased after BR application. Moreover, gel shift and transient expression assays indicated that LcBZR1/2 could suppress the transcription of
LcACS1
/
4
and
LcACO2
/
3
by specifically binding to their promoters. Importantly, ectopic expression of
LcBZR1
/
2
in
Arabidopsis
significantly delayed floral organ abscission and suppressed ethylene biosynthesis. Collectively, our results suggest that BRs suppress ET-induced fruitlet abscission through LcBZR1/2-controlled expression of genes related to ethylene biosynthesis in litchi. In addition, similar results were observed in the
Arabidopsis
gain-of-function mutant
bzr1-1D
, which showed delayed floral organ abscission in parallel with lower expression of
ACS
/
ACO
genes and reduced ethylene production, suggesting that the mechanism of BZR-controlled organ abscission via regulation of ethylene biosynthesis might be conserved in
Arabidopsis
. |
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ISSN: | 2662-6810 2052-7276 2052-7276 |
DOI: | 10.1038/s41438-021-00540-z |