Laticifers in Sapindaceae: Structure, Evolution and Phylogenetic Importance.

Area of Science:

• Plant anatomy
• Plant evolution
• Phytochemistry

Background:

• Laticifer presence and structure in Sapindaceae are not well-documented, likely due to low latex production in many species.
• Previous research has underestimated the occurrence of laticifers within this plant family.

Purpose of the Study:

• To investigate the occurrence, structure, development, and chemical composition of laticifers in 67 Sapindaceae species.
• To reconstruct the evolutionary history of laticifers within the Sapindaceae family.

Main Methods:

• Histological analysis of shoot tissues from herbarium and fresh specimens.
• Coding of laticifer-derived characters for phylogenetic analysis.
• Reconstruction of ancestral states using Bayesian stochastic mapping and maximum likelihood estimation.

Main Results:

• Only articulated non-anastomosing laticifers were identified in Sapindaceae, differentiating early in shoot development and located in cortex, phloem, and pith.
• Latex is primarily composed of lipids, with callose and suberin found in laticifer cell walls in certain genera.
• Laticifers have five independent origins in Sapindaceae, with secondary losses observed; callose in laticifer cell walls evolved independently twice, notably in Paullinieae.

Conclusions:

• Laticifer occurrence in Sapindaceae is more extensive than previously reported, with significant evolutionary events including multiple origins and losses.
• The presence of callose in laticifer cell walls, particularly in Paullinia and Serjania, may represent a key innovation promoting diversification.
• Laticifer characteristics offer valuable insights into generic relationships and evolutionary patterns within the Sapindaceae family.