Circadian Rhythm Synchronization Of Physiological Metabolism Among Inter-ramets In Buchloe Dactyloides (Nutt.) Engelm Under Heterogeneous Photoperiod

It is the basis of biological survival of life on earth and development to keep circadianclocks and periodic rhythm synchronized. Up to date, the physiological metabolism associatedwith biological clock adjustment mechanism is not clear. The study about when and how tokeep circadian clocks and exogenous periodic rhythm synchronized after the biological clockperceived the exogenous environment changes has no breakthrough. In addition, physiologicalintegration is a property of many rhizomatous and stoloniferous clonal plant species, whichimproves their ability for survival, propagation and resource to cope with habitat heterogeneity.At present, researchs about clonal plants under heterogeneous moisture, nutrients and otherheterogeneous resources well documented, whereas studys of clonal plants underheterogeneous photoperiod enviroment have been little explored.In this project, we used ramets of Buchloe dactyloides (Nutt.) Engelm. to comprehend thereactions of physiological metabolism in the process of entrainment using the characteristics ofphysiological integration of clonal plants, we studied the time-course of concentration ofsoluble sugar and hormones and activityof antioxidase in leaves of connected ramets inbuffalograss under homogeneous photoperiod during24hours to confirm whether the twoconnectedclonal ramets won synchronized circadian clocks. On that basis, we continued tostudied physiological metabolism in leaves of connected clonal ramets in buffalograss underheterogeneous photoperiod. According to that, we would know whether and how the clonalramets in buffalograss to complete the synchronization. The results were shown as follows:(1) We used B. dactyloides. connected ramets cultivated under homogeneous photoperiodfor7days as materials to research physiological metabolic response of buffalograss leaves, bymeasuring soluble sugar and hormones content and antioxidase activity every4hours. Wefound that the time-course of concentrationof soluble sugar, IAA and ABA, and activity ofsuperoxide dismutase (SOD), peroxidase (POD), catalase (CAT) in leavesshowed circadian rhythmics expression patterns (with peaks at20o’clock and trough at8o’clock). Then wefound the same circadian rhythmics when cultivating connected ramets under continuous lightenvironment. We considered physiological metabolic response tends to be synchronized withthe environmental light dark cycle rhythm.(2) Then we used B. dactyloides. connected rametscultivated under heterogeneousphotoperiod envirnments for7days to research physiological metabolic response of connectedramets by measuring soluble sugar and hormones content and antioxidase activity every4hours. We found that the time-course of concentrationof soluble sugar, IAA and ABA, andactivity of superoxide dismutase, peroxidase, catalasein leaves of connected ramets showedthe opposite variation trend, The old ramets still showed circadian rhythmics expression whichis nearly sinusoidalrhythmics. While the new ramets are opposite with the old ramets; theyshowed approximate cosinerhythmics. With the prolonging of treatment time, the time-courseof concentrationof soluble sugar, IAA and ABA, and activity of SOD, CAT in leaves ofconnected ramets presented convergence of variation trend, and they all showed circadianrhythmics expression which is nearly sinusoidalrhythmics except POD. It indicated thatheterogeneous photoperiodenvirnments can be percept by connected clonal ramet ofbuffalograss. Then regulation of physiological integration can realize the materialtransportation and signal transduction through the two connected ramets, and it played animportant roles in the adaptability of heterogeneous photoperiodenvirnments.In conclusion, the time-course of concentrationof soluble sugar, IAA and ABA, andactivity of in buffalograss,which are cultured under homogeneous photoperiod enviromentsshowed circadian rhythmics synchronized with enviroments’ photoperiod. When buffalograssare cultured under heterogeneous photoperiod, the circadian rhythmics which is synchronizedwith enviroments’ photoperiod would change. But regulation of physiological integrationcanregulationphysiological metabolism resulting in circadian rhythmics synchronized.