Hydration-state-responsive proteins link cold and drought stress in spinach.

Area of Science:

• Plant Physiology
• Molecular Biology
• Stress Physiology

Background:

• Spinacia oleracea L. (spinach) seedlings undergo cold acclimation at nonfreezing temperatures (0-10° C).
• Cold acclimation enhances cellular dehydration tolerance and involves synthesizing cold-acclimation proteins.
• Two specific proteins (160 and 85 kDa) accumulate with prolonged low-temperature exposure.

Purpose of the Study:

• To investigate the relationship between cold acclimation, water stress, and the accumulation of specific cold-acclimation proteins in spinach.
• To determine if common mechanisms link responses to cold and osmotic stress.

Main Methods:

• Exposing spinach seedlings to low nonfreezing temperatures (0-10° C).
• Inducing water stress by withholding water from seedlings grown at 25° C.
• Monitoring the accumulation of 160 and 85 kDa proteins and assessing freezing tolerance.

Main Results:

• Low temperatures induced cold acclimation and increased accumulation of 160 and 85 kDa proteins.
• A slight decrease in tissue water content initiated protein accumulation at noninductive temperatures.
• Severe water stress in unstressed seedlings led to significant accumulation of these proteins and maximal freezing tolerance.

Conclusions:

• Cold acclimation and water stress responses in spinach share common underlying mechanisms.
• The 160 and 85 kDa proteins are strongly linked to osmotic stress responses, including cold acclimation and dehydration tolerance.