Glucose is a global regulator of growth and metabolism that is evolutionarily conserved from unicellular microorganisms to multi-cellular animals and plants. In photosynthetic plants, glucose shows hormone-like activities and modulates many essential processes, including embryogenesis, germination, seedling development, vegetative growth, reproduction and senescence. Expression analysis was carried out to evaluate the effect of glucose on ethylene biosynthesis and signaling in petunia flower. Flowers at the anthesis stage were treated with glucose solution and changes in ACS2, EIL-1 and EIN2 genes were monitored over time. While control flowers displayed a typical peak of ethylene production, flowers treated with glucose did not. Glucose appeared to exert its effect on ethylene biosynthesis by suppressing ACS2 expression. Interestingly, exposure to glucose treatment resulted in a rapid decrease in EIN2 expression in petals. However, EIN2 mRNA maintained to notably higher levels in petals of control flowers and decrease in mRNA level was slower than glucose-treated petals. Also, changes in EIL-1 mRNA levels in glucose-treated flowers showed that glucose delays increase of EIL-1 mRNA accumulation in petals. These results indicate that glucose may play an important role in ethylene-associated regulation of flower senescence.

Keywords