Evolution of fast root gravitropism in seed plants

Area of Science:

• Plant biology
• Evolutionary biology
• Developmental biology

Background:

• Gravitropism is crucial for plant survival on land, enabling roots to seek water and nutrients.
• Root gravitropism allows plants to anchor themselves firmly in the soil.

Purpose of the Study:

• To investigate the evolutionary origins of efficient root gravitropism in seed plants.
• To identify the key anatomical and functional innovations driving the evolution of root gravitropism.

Main Methods:

• Interspecies complementation experiments were used to study gene function.
• Protein domain swapping was employed to analyze the roles of specific protein regions.
• Investigated the subcellular localization of PIN proteins in root tips.

Main Results:

• An architectural innovation, with gravity perception in root tips and shootward auxin transport, emerged with seed plants.
• Functional innovations in PIN family auxin transporters led to the evolution of gravitropism-specific PINs.
• The apical/shootward localization of PIN proteins connected gravity perception sites with growth response via auxin.

Conclusions:

• The evolution of root gravitropism in seed plants involved coordinated anatomical and functional changes.
• This adaptation facilitated a rapid gravitropic response, crucial for terrestrial life.
• Specialized auxin transport mechanisms were key to the evolution of efficient root gravitropism in seed plants.