Are We Chasing a Wild Goose? Rethinking Breeding Targets for Salinity Stress Tolerance in Rice.

Area of Science:

• Agricultural Science
• Plant Physiology
• Molecular Biology

Background:

• Salinity stress poses a significant threat to global agriculture, particularly impacting rice production due to its high sensitivity.
• Developing salt-tolerant rice is crucial for food security, as rice is a staple for over half the world's population.

Purpose of the Study:

• To investigate the effects of salt stress on rice growth and identify key physiological parameters for high-throughput screening.
• To build predictive regression models for rice salinity tolerance based on stomatal conductance, chlorophyll content, and ion content.

Main Methods:

• Ten rice genotypes were subjected to three salinity levels (0, 50, and 100 mM NaCl).
• Regression models were developed to correlate plant growth (shoot dry weight) with physiological parameters: stomatal conductance (Gs), chlorophyll content (SPAD), and shoot potassium (K+) and sodium (Na+) concentrations.
• In silico modeling was employed to determine the best predictive model.

Main Results:

• The most effective model for predicting shoot dry weight (SDW) incorporated Gs, SPAD, and shoot K+ content.
• Shoot Na+ content did not significantly influence biomass accumulation under salinity stress.
• These findings challenge the conventional breeding approach focused on Na+ exclusion.

Conclusions:

• Enhancing potassium (K+) retention and optimizing stomatal regulation are more promising strategies for improving rice salinity tolerance than solely focusing on sodium (Na+) exclusion.
• Revisiting genetic targets for Gs regulation, K+ homeostasis, and chlorophyll maintenance is essential for developing climate-resilient rice varieties.