Phosphofructokinase and glucose-6-phosphate dehydrogenase in response to drought and bicarbonate stress at transcriptional and functional levels in mulberry

Drought and bicarbonate stress are the most common abiotic stresses limiting plant growth and crop production all over the world. Glycolytic and pentose phosphate pathways have important effects on the resistance response of plants to abiotic stress. Phosphofructokinase (PFK) and glucose-6-phosphate dehydrogenase (G6PDH) are the rate limiting enzymes of the two pathways which control carbon flow through the two pathways, respectively. In Morus alba L. leaves, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and the proline content increased under drought and bicarbonate stress at first, and then decreased. At the functional level, drought and bicarbonate stress exert an activating effect on the G6PDH activity and an inhibitory effect on the PFK activity in M. alba leaves. At the transcriptional level ATP-PFK , PPi-PFK and G6PDH genes showed no significant change under 80 g/L PEG 6000 treatment. The changes were observed at the ATP-PFK , PPi-PFK and G6PDH mRNA levels under 30 mM NaHCO 3 treatment. Although M. alba stopped growing under two different treatments and the changes of G6PDH and PFK are different suggesting that may be additional factors playing important roles in glucose and energy metabolism in plant responses to stresses.