Heat Stress Factors Expressed during Seed Maturation Differentially Regulate Seed Longevity and Seedling Greening

Area of Science:

• Plant Biology
• Molecular Genetics

Background:

• Heat Stress Factor A9 (A9) is a seed-specific transcription factor known to influence seed longevity.
• A9 also plays a role in phytochrome-dependent seedling greening.

Purpose of the Study:

• To investigate the potential role of A9 in cryptochrome-mediated blue-light responses.
• To determine if A9 requires coactivators for its effects on seedling photomorphogenesis, contrasting with its role in seed longevity.

Main Methods:

• RNA sequencing of imbibed seeds to analyze A9's transcriptomic effects.
• Seed-specific overexpression of A9 to assess its impact on blue-light responses.
• Loss-of-function analyses using dominant-negative and inactive A9 forms to study greening and longevity.

Main Results:

• RNA-seq data suggested A9 influences blue-light responses.
• Overexpression of A9 enhanced blue-light responses in seedlings.
• Loss-of-function studies confirmed A9's role in greening and indicated it does not require A4a or other factors for this function.

Conclusions:

• A9 differentially regulates seed longevity and seedling photomorphogenesis.
• A9 alone is sufficient to enhance both phytochrome- and cryptochrome-dependent greening effects.
• A9's function in photomorphogenesis is independent of the coactivators needed for its role in seed longevity.