Cell-Autonomous and Non-Cell-Autonomous Mechanisms Concomitantly Regulate the Early Developmental Pattern in the Kelp...

Area of Science:

• Developmental Biology
• Marine Botany
• Algal Research

Background:

• Brown algae, like Saccharina latissima, are unique multicellular organisms with distinct embryogenesis.
• Understanding brown algal embryogenesis is limited to a few species across different orders.
• Saccharina latissima belongs to the Laminariales order, exhibiting unique developmental patterns.

Purpose of the Study:

• To investigate the control of cell growth and division orientation in Saccharina latissima embryos.
• To elucidate the roles of apical and basal cells in early brown algal development.
• To compare Saccharina latissima embryogenesis with other known brown algal models.

Main Methods:

• Laser ablation experiments were performed on early-stage Saccharina latissima embryos (pre-8-cell stage).
• Cellular functions related to growth and division orientation were analyzed post-ablation.
• Cell-autonomous and non-cell-autonomous mechanisms were assessed by observing developmental compensation.

Main Results:

• Apical cells primarily contribute to embryo growth.
• Basal cells regulate cell division orientation by inhibiting longitudinal divisions, preventing premature widening.
• Growth appears cell-autonomous, with no compensatory growth observed after ablation.
• Division orientation in the apical region is influenced by basal cells, indicating a polarized, non-cell-autonomous mechanism.

Conclusions:

• Early embryogenesis in Saccharina latissima involves a complex interplay of cell-autonomous growth and non-cell-autonomous division orientation.
• This developmental control mechanism differs significantly from other brown algae, which rely on environmental cues for polarity establishment.
• The findings provide novel insights into the early developmental strategies of brown algae.