Seed-to-Seedling Transition in Pisum sativum L.: A Transcriptomic Approach.

Area of Science:

• Plant Biology
• Developmental Biology
• Molecular Biology

Background:

• The transition from seed to seedling is a critical developmental stage in the plant life cycle.
• This transition involves significant physiological and molecular changes, including the initiation of embryonic root growth.
• Understanding the regulatory mechanisms governing this shift is essential for plant science.

Purpose of the Study:

• To investigate the molecular changes occurring during the seed-to-seedling transition in *Pisum sativum* L.
• To identify key genes and pathways involved in the loss of desiccation tolerance during this transition.
• To compare transcriptomic profiles before and after radicle protrusion.

Main Methods:

• Germination of *Pisum sativum* L. seeds for 72 hours.
• Sampling of embryonic axes before and after radicle protrusion.
• RNA sequencing-based transcriptomics to analyze gene expression differences.

Main Results:

• Identified 24,184 differentially expressed genes during the seed-to-seedling transition.
• 2101 genes showed increased expression, related to metabolism, photosynthesis, cell wall biosynthesis, redox status, and stress response.
• 415 genes showed decreased expression, including those involved in water deprivation and abscisic acid (ABA) response, with specific genes (LTI65, LTP4, HVA22E) and ABA transcription factors (ABI3, ABI4, ABI5) highlighted.

Conclusions:

• The loss of desiccation tolerance during the seed-to-seedling transition is linked to a metabolic switch and changes in water and oxidative status.
• Specific genes involved in water deprivation and ABA signaling, such as HVA22E, ABI4, and ABI5, play crucial roles and are conserved across species.
• These findings provide insights into the genetic regulation of seed dormancy release and early seedling development.