Grafting is widely used in cucumbers to enhance their tolerance to environmental stress.Compatibility is a key factor for successful grafting,however,the physiological mechanisms that affect grafting compatibility are...Grafting is widely used in cucumbers to enhance their tolerance to environmental stress.Compatibility is a key factor for successful grafting,however,the physiological mechanisms that affect grafting compatibility are not clear.This study aimed to investigate the physiological mechanism underlying cucumber/pumpkin grafting compatibility.Two pumpkin cultivars with significant differences in compatibility,Figleaf gourd(compatible rootstock,Cf)and Dongyangshenli(incompatible rootstock,Cmo),were used as rootstocks.Three cucumber cultivars with different growth rates were used as scions,including cucumber‘Shenluchunsi’(strong growth,V1),‘Cuilü’(weak growth,V2),and‘Liangyoulüjian 102’(medium growth,V3).Six grafting combinations(V1/Cf,V2/Cf,V3/Cf,V1/Cmo,V2/Cmo,and V3/Cmo)were used to analyze the effect of scion and rootstock varieties,as well as the chemical composition of the exudate from the stem cutting surface,on the compatibility of grafted plants.Here,we found that rootstock was closely correlated with the compatibility of cucumber/pumpkin grafted plants.The sucrose content in the exudate of the stem,enzyme activity,and the expression of genes related to sucrose biosynthesis in Cmo were significantly higher than those in Cf.Correlation analysis showed that the sucrose content difference between the exudate of rootstock and scion stems was negatively correlated with graft compatibility.Exogenous treatment with a 0.5%sucrose solution on the scions significantly reduced the difference in sucrose content between rootstock and scion and enhanced graft survival rate in the incompatible combination.The stem segment grafting experiment in vitro found that the high difference in sucrose concentration between the rootstock and scion decreased the grafting compatibility of cucumber/pumpkin by reducing the adhesion of the cutting surface.Taken together,the higher sucrose concentration difference between rootstock and scion decreased the adhesion of the cutting surface,resulting in the incompatibility of cucumber/pumpkin grafted plants.展开更多
The yellowing of leaves caused by the decomposition of chlorophyll(Chl)is a characteristic event during senescence,which can be induced by various environmental stresses.However,the molecular mechanisms of high temper...The yellowing of leaves caused by the decomposition of chlorophyll(Chl)is a characteristic event during senescence,which can be induced by various environmental stresses.However,the molecular mechanisms of high temperature-induced Chl degradation in horticultural plants remain poorly understood.Here,we found that heat stress induced Chl degradation and the expression of ABI5 and MYB44 in cucumber.Silencing of ABI5 compromised heat stress-induced Chl degradation,and the transcription of pheophytinase(PPH)and pheophorbide a oxygenase(PAO),two key genes in Chl catabolic pathway,but silencing of MYB44 exhibited the opposite results.Furthermore,ABI5 interacted with MYB44 in vitro and in vivo.ABI5 positively regulated heat stress-induced Chl degradation through two pathways.ABI5 directly bound to PPH and PAO promoters to promote their expression,leading to accelerating Chl degradation.On the other hand,the interaction between ABI5 and MYB44 reduced the binding of MYB44 to PPH and PAO promoters and led to the ubiquitination-depended protein degradation of MYB44,thereby alleviating the transcription inhibitory effect of MYB44 on PPH and PAO.Taken together,our findings propose a new regulatory network for ABI5 in regulating heat stress-induced Chl degradation.展开更多
基金supported by grants from the Gansu Provincial Science and Technology Plan Project(Grant No.22CX8NA030)the National Natural Science Foundation of China(Grant No.32272793)the China Agriculture Research System(Grant No.CARS-23).
文摘Grafting is widely used in cucumbers to enhance their tolerance to environmental stress.Compatibility is a key factor for successful grafting,however,the physiological mechanisms that affect grafting compatibility are not clear.This study aimed to investigate the physiological mechanism underlying cucumber/pumpkin grafting compatibility.Two pumpkin cultivars with significant differences in compatibility,Figleaf gourd(compatible rootstock,Cf)and Dongyangshenli(incompatible rootstock,Cmo),were used as rootstocks.Three cucumber cultivars with different growth rates were used as scions,including cucumber‘Shenluchunsi’(strong growth,V1),‘Cuilü’(weak growth,V2),and‘Liangyoulüjian 102’(medium growth,V3).Six grafting combinations(V1/Cf,V2/Cf,V3/Cf,V1/Cmo,V2/Cmo,and V3/Cmo)were used to analyze the effect of scion and rootstock varieties,as well as the chemical composition of the exudate from the stem cutting surface,on the compatibility of grafted plants.Here,we found that rootstock was closely correlated with the compatibility of cucumber/pumpkin grafted plants.The sucrose content in the exudate of the stem,enzyme activity,and the expression of genes related to sucrose biosynthesis in Cmo were significantly higher than those in Cf.Correlation analysis showed that the sucrose content difference between the exudate of rootstock and scion stems was negatively correlated with graft compatibility.Exogenous treatment with a 0.5%sucrose solution on the scions significantly reduced the difference in sucrose content between rootstock and scion and enhanced graft survival rate in the incompatible combination.The stem segment grafting experiment in vitro found that the high difference in sucrose concentration between the rootstock and scion decreased the grafting compatibility of cucumber/pumpkin by reducing the adhesion of the cutting surface.Taken together,the higher sucrose concentration difference between rootstock and scion decreased the adhesion of the cutting surface,resulting in the incompatibility of cucumber/pumpkin grafted plants.
基金This work was funded by the National Natural Science Foundation of China(31872152)the Open Fundation of the Key Laboratory of Horticulture for Southern Mountainous Regions,Ministry of Education,Southwest University,the China Agriculture Research System(CARS-23)the Postdoctoral Research Funding Scheme of Jiangsu Province(2019 K071).
文摘The yellowing of leaves caused by the decomposition of chlorophyll(Chl)is a characteristic event during senescence,which can be induced by various environmental stresses.However,the molecular mechanisms of high temperature-induced Chl degradation in horticultural plants remain poorly understood.Here,we found that heat stress induced Chl degradation and the expression of ABI5 and MYB44 in cucumber.Silencing of ABI5 compromised heat stress-induced Chl degradation,and the transcription of pheophytinase(PPH)and pheophorbide a oxygenase(PAO),two key genes in Chl catabolic pathway,but silencing of MYB44 exhibited the opposite results.Furthermore,ABI5 interacted with MYB44 in vitro and in vivo.ABI5 positively regulated heat stress-induced Chl degradation through two pathways.ABI5 directly bound to PPH and PAO promoters to promote their expression,leading to accelerating Chl degradation.On the other hand,the interaction between ABI5 and MYB44 reduced the binding of MYB44 to PPH and PAO promoters and led to the ubiquitination-depended protein degradation of MYB44,thereby alleviating the transcription inhibitory effect of MYB44 on PPH and PAO.Taken together,our findings propose a new regulatory network for ABI5 in regulating heat stress-induced Chl degradation.
