Photosynthesis Optimized across Land Plant Phylogeny

Area of Science:

• Plant Physiology
• Evolutionary Biology

Background:

• Limited data previously existed on photosynthesis and its limiting factors in non-crop/model plants.
• Emerging data from basal terrestrial plants offer new insights into photosynthetic evolution.

Purpose of the Study:

• To explore the increase in photosynthetic capacity (Amax) from basal to advanced plant groups.
• To investigate the changing balance of limiting factors (mesophyll conductance (lm), stomatal conductance (ls)) across plant evolution.

Main Methods:

• Comparative analysis of photosynthetic data across diverse plant groups.
• Examination of the transition from single limitations to co-limitations of lm and ls.

Main Results:

• Bryophytes and lycophytes show predominant mesophyll conductance limitation (lm).
• Pteridophytes and gymnosperms exhibit co-limitation by stomatal conductance (ls) and lm.
• Angiosperms achieve a balanced co-limitation of all three factors, leading to maximum photosynthetic capacity (Amax).

Conclusions:

• Photosynthetic capacity (Amax) is optimized through a progressive balancing of limiting factors across plant evolution.
• Understanding these evolutionary shifts in photosynthetic limitations provides a basis for future crop improvement.
• The study highlights the importance of mesophyll and stomatal conductance in driving photosynthetic efficiency.