Field-work reveals a novel function for MAX2 in a native tobacco's high-light adaptions

Area of Science:

• Plant Biology
• Molecular Ecology
• Genetics

Background:

• Strigolactone (SL) and karrikin (KAR) signaling pathways regulate plant development and stress responses.
• Understanding the ecological roles of these pathways in natural environments is crucial for crop improvement.

Purpose of the Study:

• To investigate the ecological function of SL and KAR signaling in wild tobacco (Nicotiana attenuata).
• To determine the role of MAX2 in SL/KAR signaling and its impact on plant fitness and stress adaptation in the field.

Main Methods:

• Generated transgenic Nicotiana attenuata lines with silenced SL/KAR signaling components (irMAX2, irD14, irKAI2).
• Grew plants in controlled glasshouse conditions and natural field environments over four seasons.
• Conducted transcriptomic analysis and manipulated light conditions (PAR, UV-B) to assess plant responses.

Main Results:

• irMAX2 plants exhibited increased shoot branching, leaf bleaching, reduced sugar content, and increased amino acid content in the field, but not in the glasshouse.
• Field-grown irMAX2 plants showed decreased lifetime fitness and increased susceptibility to herbivory.
• Leaf bleaching in irMAX2 was linked to high-light intensity responses, including decreased lutein and altered gene expression, and was reversible by reducing PAR.

Conclusions:

• NaMAX2 plays a critical role in high-light adaptation and fitness optimization, independent of its function in SL and KAR signaling.
• Studying gene function in natural environments is essential for understanding plant adaptation and potential applications.