In germinating seeds under unfavorable environmental conditions, the mobilization of stores in the cotyledons is delayed, which may result in a different modulation of carbohydrates balance and a decrease in seedling vigor. Tall fescue (Festuca arundinacea Schreb.) caryopses grown at 4°C in the dark for an extended period in complete absence of nutrients, showed an unexpected ability to survive. Seedlings grown at 4°C for 210 days were morphologically identical to seedlings grown at 23°C for 21 days. After 400 days, seedlings grown at 4°C were able to differentiate plastids to chloroplast in just few days once transferred to the light and 23°C. Tall fescue exposed to prolonged period at 4°C showed marked anatomical changes: cell wall thickening, undifferentiated plastids, more root hairs and less xylem lignification. Physiological modifications were also observed, in particular related to sugar content, GA and ABA levels and amylolytic enzymes pattern. The phytohormones profiles exhibited at 4 and 23°C were comparable when normalized to the respective physiological states. Both the onset and the completion of germination were linked to GA and ABA levels, as well as to the ratio between these two hormones. All plants showed a sharp decline in carbohydrate content, with a consequent onset of gradual sugar starvation. This explained the slowed then full arrest in growth under both treatment regimes. The analysis of amylolytic activity showed that Ca2+ played a central role in the stabilization of several isoforms. Overall, convergence of starvation and hormone signals meet in crosstalk to regulate germination, growth and development in tall fescue.

• MeSH
• alfa-amylasy metabolismus   MeSH
• buněčná stěna metabolismus   fyziologie   MeSH
• časové faktory MeSH
• Festuca metabolismus   fyziologie   MeSH
• fyziologická adaptace fyziologie   účinky záření   MeSH
• fyziologický stres fyziologie   MeSH
• gibereliny metabolismus   MeSH
• kořeny rostlin metabolismus   fyziologie   MeSH
• kotyledon metabolismus   fyziologie   MeSH
• kyselina abscisová metabolismus   MeSH
• lignin metabolismus   MeSH
• nízká teplota MeSH
• rostlinné proteiny metabolismus   MeSH
• sacharidy analýza   MeSH
• semenáček fyziologie   MeSH
• světlo MeSH
• tma MeSH
• vápník metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH