Expression analysis of the gene family associated with raffinose accumulation in rice seedlings under cold stress

A considerable increase in the concentration of raffinose was detected in rice seedlings exposed to chilling for more than 4 days. The content of raffinose in leaf blades increased from hardly detectable levels (0–1 days) to approximately 9 mg/g FW after 11 days of chilling treatment. Accumulation occurred in leaf blades but not in sheaths. Analysis of the expression of candidate genes related to galactinol and raffinose synthesis revealed that transcript levels of two galactinol synthase and four raffinose synthase genes increased in leaf blades before the accumulation of raffinose became detectable.