低温胁迫对白菜型冬油菜根中3种酶活性的影响OA

The growth of winter Brassica rapa is easily affected by low temperature environments.Investigating changes in the activities of key enzymes involved in respiratory metabolism in the roots of winter Brassica rapa under low temperature can provide a theoretical basis for germplasm innovation and cold-resistance breeding of winter rapeseed.Seedlings of Longyou 7 and Tianyou 4 were used as materials,3 low temperature treatments were set at day/night temperatures of 15℃/10℃,10℃/5℃,and 5℃/0℃,with 20℃/15℃as the control.The activities of hexokinase,phosphofructokinase,and pyruvate kinase in roots of winter Brassica rapa after low temperature stress were determined.Results showed that with the decrease of stress temperature,the 3 enzyme activities in the roots of winter Brassica rapa increased first and then decreased.Under low temperature stress,the activities of hexokinase,phospho-fructokinase,and pyruvate kinase in the roots of Longyou 7 were significantly enhanced,and the magnitude of change was greater than that in Tianyou 4.When the day/night temperature was 10℃/5℃,the activities of the 3 enzymes in winter rapeseed roots reached their highest levels.Compared with the control,the activities of hexokinase,phosphofructokinase,and pyruvate kinase in Longyou 7 in-creased by 196.59％,54.43％,and 112.83％,respectively.At a day/night temperature of 15℃/10℃,these activities in Longyou 7 in-creased by 140.11％,23.60％,and 77.45％,respectively,compared with the control.At a day/night temperature of 5℃/0℃,they in-creased by 148.75％,26.35％,and 73.16％,respectively.Principal component analysis showed that phosphofructokinase was the key enzyme index,and the variance contribution rate of the first principal component was 92.63％.The membership function analysis showed that the comprehensive membership function value of Longyou 7 was significantly higher than that of Tianyou 4,and that a day/night temperature of 10℃/5℃ was the critical low temperature for the enhancement of enzyme activity in the root.Hexokinase and phosphofructokinase were the key enzymes of respiratory metabolism in the root of winter Brassica rapa.The results of linear combina-tion coefficient and weight analysis showed that hexokinase activity in the root of winter Brassica rapa was the dominant index in re-sponse to low temperature.In summary,Longyou 7,a strong cold-resistant variety of winter Brassica rapa at low temperature,adapts to low temperature stress by enhancing the activities of hexokinase,phosphofructokinase and pyruvate kinase in roots,phosphofructoki-nase activity playing a key role.Therefore,phosphofructokinase activity can be used as a major respiratory indicator for screening.