Molecular responses to recurrent drought in two contrasting rice genotypes

Area of Science:

• Plant Physiology
• Molecular Biology
• Agricultural Science

Background:

• Drought stress significantly impacts crop yields and food security.
• Plants may possess mechanisms to 'remember' previous stress events, influencing their response to subsequent stresses.
• Understanding drought memory is crucial for developing resilient crop varieties.

Purpose of the Study:

• To investigate the 'drought memory' phenomenon in two rice genotypes: BRS Querência (flooded) and AN Cambará (dryland).
• To determine if prior drought exposure enhances tolerance to subsequent water deficit through molecular and physiological changes.
• To evaluate the role of stomatal regulation and transcription factors in drought memory.

Main Methods:

• Two rice genotypes were subjected to a pre-treatment of water deficit (10% VWC) at the vegetative stage (V5).
• Plants were rehydrated and then exposed to a second drought period at the reproductive stage (R1-R2).
• Physiological (water status, stomatal regulation) and molecular (transcription factor expression) analyses were performed after rehydration and the second drought stimulus.

Main Results:

• Multivariate analysis confirmed a drought memory effect in the AN Cambará (dryland) genotype.
• Pre-treated and rehydrated AN Cambará plants showed improved water status maintenance after the second drought stimulus.
• Enhanced stomatal regulation in pre-treated AN Cambará plants contributed to better water status maintenance.

Conclusions:

• Drought pre-treatment induces a memory effect in the dryland rice genotype AN Cambará.
• This memory effect enhances the plant's ability to tolerate subsequent drought events through improved physiological responses.
• Stomatal regulation plays a key role in mediating drought memory and improving water deficit tolerance in rice.