Dynamic temporal transcriptome analysis reveals grape VlMYB59-VlCKX4 regulatory module controls fruit set.

Area of Science:

• Plant Science
• Molecular Biology
• Agricultural Science

Background:

• Fruit set is critical for crop yield and quality.
• N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) is used to promote grape fruit set, but its molecular mechanism is unclear.

Purpose of the Study:

• To elucidate the molecular mechanism of CPPU-induced grape fruit set.
• To identify key genes and regulatory pathways involved in grape fruit set.

Main Methods:

• Stage-specific transcriptome profiling of 'Kyoho' grape under CPPU treatment and natural conditions.
• Value differentially expressed gene (VDEG) analysis.
• Gene overexpression in *Arabidopsis thaliana* to validate gene function.

Main Results:

• CPPU treatment significantly enriched cytokinin pathways during grape fruit set.
• The VlMYB59-VlCKX4 module was identified as a key regulator, with VlMYB59 directly activating VlCKX4 expression.
• Overexpression of VlCKX4 and VlMYB59 promoted fruit set in *Arabidopsis*.

Conclusions:

• A novel regulatory pathway involving VlMYB59 and VlCKX4 in CPPU-induced grape fruit set was uncovered.
• This finding provides crucial insights into grape fruit set mechanisms and potential genetic resources for breeding.