BRASSICA NAPUS( بررسي اثر دماي بهاره سازي بر تغييرات كمي و الكتروفورزي پروتيين هاي محلول برگ ارقام بهاره و پاييزه كلزا

Study of a vernalization temperature on quantitative and electrophoretic changes of leaf soluble proteins in winter and spring canola (Brassica napus) cultivars

Quantitative and electrophoretic patterns of leaf soluble proteins of canola (Brassica napus L.) winter (cv. Symbol) and spring (cv. Hyola 401) cultivars were assessed in response to a vernalization temperature (4°C). Seeds were grown in a growth chamber at 15/10°C (day/night), with 140 W m z light density and 1618 h photoperiod. Control plants were grown continuously in these conditions until day 56. On day 30 (4ʹ1ʹ fully expanded leafy stage), cold treated seedlings were transferred to 4°C, followed by transfer to original conditions. Seedlings were sampled every 48 h for leaf fresh weight measurements. Soluble proteins were extracted from the leaves, and their amounts were measured, using spectrophotometery. Proteins data were analysed as 3-factorial experiment on the basis of completely random design (CRD): cultivar (2 levels), temperature (2 levels), and sampling time (14 levels) in 3 replications. Then, 45 µg of proteins was loaded on SDS-PAGE gel with 15% density. ANOVA results showed that all main effects and their interactions were highly significant. Temperature alterations showed no substantial effects on proteins amount in the cold-treated leaves of spring canola but, considerable accumulation of proteins was recognized in those of winter canola. This accumulation was detected from 8 day at 4°C continuing until 2 day of transfer from cold to the 15°C-conditions (day 54) in the winter cultivar. In the latter cultivar, the 2-week cold-treated seedlings (day 44) produced a new 47.7 kDa cold-induced polypeptide in their leaves compared with the controls: such response was identified 2 d later in the cold-treated seedlings of spring cultivar. This pattern was lasted until 18 d at 4°C (day 48) in the leaves of both cultivars but, after the return to 15°C, it disappeared in the spring earlier than the winter canola. Moreover, changes in the intensity of some protein patterns were distinguished in both cultivars at 4°C compared with those in the controls.