Spermidine Effects On Physiological Mechanism Of Resistance To Paraquat In Goosegrass(Eleusine Indica L.)

Goosegrass?Eleusine indica L.Gaertn?is an annual grass in the family Poaceae with a strong adaptability under various ecological conditions and listed as one of the top 10 world's worst weeds.Paraquat?PQ?,a bipyridyl,quick-acting herbicide,is widely used of weeds control in orchards,forests,fields,and roadsides.The paraquat resistance in goosegrass has become a thorny problem in the prevention and control of weeds in orchards in South China.However,the mechanism of paraquat resistance is not yet clear.Endogenous polyamines have been reported to be involved in resistance to paraquat in goosegrass,but there is relatively little research on the role of exogenous polyamines in the resistance of paraquat.The paraquat-resistant and sensitive biotypes were used as materials in this study.The physiological and biochemical parameters of goosegrass seedlings were determined under Spd and PQ treatments.The growth and development characteristics of two biotypes were compared.The physiological and biochemical parameters of resistant biotypes and Spd-treated sensitive biotypes were analyzed under PQ conditions.To further reveal the mechanism of paraquat resistance in goosegrass.Reveal the physiological mechanism of PQ resistance induced by exogenous Spd-enhanced biotypes of goosegrass.The results are as follows:?1?Pretreatment with 0,0.5,1.0,1.5,and 2.0 mmol·L^-1 Spd could alleviate the effect of paraquat on S biotype of goosegrass.The specific performance is the increase of fresh and dry weight of goosegrass.Spd treatment with 1.0 mmol·L^-1 exhibited significantly highest effects on the growth of seedlings.?2?Compared with PQ-treated R biotype,the fresh and dry weight of S biotype treated with Spd+PQ had similar trends.The fresh and dry weights of S biotypes of goosegrass were decreased after PQ treatment within 0 to 48 h.Compared with PQ treatment,the fresh and dry weight of S biotype were significantly increased after exposure to Spd+PQ treatment.But PQ would not affect the fresh and dry weight of R biotype within 0 to 48 h.?3?Compared with PQ treated R biotype,the changes of chlorophyll content and Fv/Fm of S biotypes treated with Spd+PQ had similar trends.The chlorophyll content and Fv/Fm of S biotype were decreased with the prolongation of after PQ treatment within 0 to48 h.Compared with PQ treatment,the chlorophyll content and Fv/Fm of S biotype were significantly increased after exposure to Spd+PQ treatment.There was no difference in the change of chlorophyll content and Fv/Fm within 0 to 48 h after PQ treatment.?4?Compared with the R biotype,the soluble protein content of S biotype was decreased after PQ treatment within 0 to 48 h.In comparison,the changes of SOD activity and MDA content of R biotypes showed an increase after PQ treatment within 0 to48 h.Compared with the control,the activities of CAT and POD of two biotypes of goosegrass showed an increase after PQ treatment within 0 to 48 h,except for the sensitive biotypes after 24 h.?5?Compared with S biotype,the content of endogenous Spd of R biotype was increased from 0 to 48 h after PQ treatment.The content of endogenous Spd of R biotype showed a decrease and then increase within 0 to 48 h after PQ treatment.Compared with PQ treatment,the content of endogenous Spd showed slowly rises and then rises rapidly within 0 to 48 h Spd+PQ treatment.The content of endogenous Spd of S biotypes was increased after 0 to 12 h and then remained in a gentle state after exposure to Spd,PQ,and Spd+PQ treatments.In summary,the S biotypes pretreatment with exogenous Spd could alleviate the control effects of PQ to some extent.PQ treatment significantly increases the content of endogenous Spd of R biotypes.To a certain extent,it was further proved that Spd participates in the mechanism of PQ resistance action in goosegrass.