Correlation Between Telomere Length And Telomerase Activity With Plant Age In Elymus Sibiricus L

As the model species of genus Elymus in Gramineae,Elymus sibiricus is the perennial sparse clustered mesoxerophytes and has many excellent characteristics,such as strong adaptability,high nutritional value,good palatability,easy cultivation and so on.Elymus sibiricus have been widely planted in the northwest and northeast of China since the 1960s.However,it has been found that the productivity of Elymus sibiricus decreased significantly after the fourth year of planting and degraded seriously in the seventh year.Short utilization period has become the main bottleneck problem that limits its large-scale cultivation for a long time.At present,Elymus sibiricus grassland is faced with many critical problems that need to be solved urgently.Based on these problems and referring to some researches ideas about senescence in other plants,the changes of telomere length and telomerase activity during the growth stages of Elymus sibiricus were determined.And also the relationships between plant age and telomere length as well as telomerase activity were studied.By which the main causes of senescence of Elymus sibiricus were analyzed.At the same time,the effects of exogenous nitrogen on telomerase activity were further explored.The results are as follows:1.The telomerase activitives in the leaves of different parts of the same Elymus sibiricus were different.At the 3,5 and 7-year Elymus sibiricus,the order of telomerase activity at the same growth stage was third upper leaves>second upper leaves>flag leaf.And also the telomerase activity increased gradually from the top to the base at any growth stage.The telomerase activitives of different organs（roots,stems and leaves）of the same Elymus sibiricus were also different at heading stage.The order of telomerase activitives in different organs of 3-year Elymus sibiricus was leaf>stem>root while 5-year was leaf>stem>root and 7-year Elymus sibiricus was stem>root>leaf.2.The telomerase activity of the whole leaf tissue of the same age Elymus sibiricus was different in different growth stages.The change of the telomerase activity of 3-year Elymus sibiricus was small in different growth stages.The telomerase activity of 5-year Elymus sibiricus increased gradually and reached the maximum（97.47 IU/L）at heading period and then decreased.The telomerase activity of 7-year Elymus sibiricus had similar variation trend,which reached the maximum（94.18IU/L）at the flowering stage while it was 7 years>3 years>5 years at the jointing stage.Elymus sibiricus leaf tissue of different plant age had different change rule.The order of telomerase activity was 7years>3 years>5 years at heading stage while it was 5 years>7 years>3 years at flowering stage and 5-year>3-year>7-year at milk-ripe stage.3.The telomere length and telomerase activity of the Elymus sibiricus decreased with the increasing of the plant age at the milk-ripe stage.A mathematical model based on the relationship between telomere length and Elymus sibiricus ages was then established by using Microsoft Excel 2016 software.It was y=-0.856.59x²-4769.2x+102535,with R²=0.8758.The mathematical model associated with telomerase activity and Elymus sibiricus age was y=1.45x²-19.683x+121.35,with R²=0.8948.4.The telomerase activitives of roots,stems,and leaves of Elymus sibiricus under different levels of nitrogen treatments were higher than that of non-nitrogen treatment.The telomerase activitives of roots,stems and leaves had significant difference at the same nitrogen treatment.The telomerase activity was leaves>stems>roots at the treatments of N₄₅ and N₆₀.Leaves had the highest telomerase activity（80.44 IU/L and72.47 IU/L,respectively）and were significant difference from stems and roots（P<0.05）,while at the level of N₇₅,the telomerase activity was stems（78.79 IU/L）>leaves>roots（63.78 IU/L）.At the N₉₀ level,the telomerase activity was roots（82.56 IU/L）>stems>leaves（57.63 IU/L）.The telomerase activity of leaves was significantly different from roots and stems（P<0.05）.At the N₁₀₅ level,the telomerase activity was leaves>roots>stems.It can be concluded that the regulations of telomerase activity during plant growth and development process is complicated.