Drought stress is one of the major factors that reduce plant growth and productivity. This study was conducted to investigate the effect of exogenous acetic acid pretreatment on drought stress tolerance response in plants. Fourteen-day-old alfalfa plants were pretreated with 15 mM acetic acid, and then subsequently subjected to drought stress for 6 days. The fresh weight and relative water content in the leaves of acetic acid pretreated alfalfa plants were increased compared to the control group. The chlorophyll and carotenoid contents were slightly decreased in the acetic acid treatment. The H2O2 and proline contents were also significantly decreased in the acetic acid treatment. These results suggest that the scavenging mechanism of reactive oxygen species in alfalfa activated by acetic acid pretreatment is involved in conferring tolerance to drought stress.

Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. Growth conditions and treatments
    2. Measurement of plant relative water content (RWC)
    3. Analysis of chlorophyll and carotenoid contents
    4. Hydrogen peroxide and proline analysis
    5. Statistical analysis
Ⅲ. RESULTS AND DISCUSSION
Ⅳ. CONCLUSIONS
Ⅴ. ACKNOWLEDGMENTS
Ⅵ. REFERENCES

• Myung-Ju Kim(Division of Applied Life Science (BK21) and Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea)
• Min-Jun Kim(Division of Applied Life Science (BK21) and Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea)
• Il-Kyu Yoon(Division of Applied Life Science (BK21) and Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea)
• Byung-Hyun Lee(Division of Applied Life Science (BK21) and Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea) Corresponding author