The Effect Of High Temperature On Pollen Germination And Tube Growth Of Pera

Based on the screening of pear pollens insensitive to high temperature,distribution of calcium,the variation of actin cytoskeleton structure,endocytosis and mitochondria structure and other signal molecules in growing pear pollen under high temperature had been investigated to elucidate the mechanism of the stopped growth of pear pollen under high-temperature stress.Finally,through the screening of against different chemical agentscontrol resisted to effect of high temperature during the period of 'Cuiguan pear'agent of flowering,pollen and chemical agents in combination of economy and high temperature resistance were found out.The main results are as follows:1.To filter out a high temperature resistant varieties of pear,the statistics of pollen germination rate and pollen tube growth in length of 73 pear cultivars were performed under different temperature(26?,37?,39?).Resistance against high temperature of pollen viability varies among different varieties.The results showed that germination rates of most of growing pollen in vitro under normal temperature are higher,while the growth of pollen tube length of different varieties change significant.After 3h in 37?,the vast majority of pear pollen tube show a pollen tube deformation,distortion and alienation of tumor like nodules.But 'Zaojinsu','26-3',,'Chexialv',,'Hongxiangsu','Zaosu','Korla pear','Qiurong' and 'Ningmengxiang' of 9 pear cultivars pollen are resistant to a high temperature of 37?.Then the 9 varieties were cultured at an extremely high temperature of 39?,and pollen tube growth stopped,even death,loss of life force.Finally 'Korla fragrant pear' in the 73 pear varieties shows a best resistance to the high temperature.2.To find mechanism that triggering the stop of pollen growth under high temperature,the physiological characteristics of the pollen tube were analyzed.The results show that,with the temperature rising,the growth of pollen tube gradually slowed,the survival rate had been reduced;when the temperature was up to 37?,the survival rate of pollen was below 40%.At the same time,along with the increasing of temperature,the relative leakage rate from the body tube has been improved.Therefore,that high temperature stress can induce the death of pear pollen tube.3.A plurality of subcellular structure and signaling molecules involved in the regulation of pear pollen tube growth.Actin cytoskeleton plays an important role during the growth of pollen tube.Respectively by optical microscope and laser confocal microscope,under the conditions of high temperature change trend of pear from actin cytoskeleton in the pollen tube structure was observed.Results showed that cultured in normal temperature of 26? in vitro pollen,pollen tube to actin filaments is a bundle of parallel to the long axis of the cell,and the pollen tube growth direction aggregation;and in the cultivation of high temperature of 37? for the pollen,pollen tube in microfilament structure has no obvious depolymerization of actin yet tip ring structure disappeared,but with the time prolonged,the pollen tube tip gradually expanded.For the function of mitochondria organelles,provides the material and energy for life activities of cells,known as the "power station",is the source of all life activities of cells.After high temperature treatment,the structure of mitochondria ridge structure confusion,blurred,or even the entire mitochondrial swelling,intima and adventitia fuzzy not clear.High temperature leading to mitochondrial structure of pear pollen tube disordered,disorder of energy metabolism,can not produce enough energy to meet the needs of all kinds of life activities of cells.Among them,the high temperature results in cessation of pear pollen tube tip of endocytosis.In the calcium signal analysis,after a high temperature of 37? treatment,the calcium distribution in the pollen tube was disrupted and gradient phenomenon disappeared.4.Eight years old of 'Cuiguan' pear was chosen to screen for the high temperature resistant agents.At the time of flowering,aqueous solution pretreatment for picked flowers were sprayed with different high temperature anti-drug combination,and daytime sub high temperature stress(35?)treatment to 26?,spraying the distilled water as the reference,screening of anti-high temperature chemical combination effect is better.The conductivity of the female flower,the content of MDA and two kinds of protective enzyme activities of superoxide dismutase(SOD)and peroxidase(POD)for the determination of physiological index 'resistance to high temperature of Cuiguan' pear.The results show that,0.4 g/L CaCl2+ 0.6 mol/L SA high temperature anti-drug combination treatment was best effective,which significantly increased the two important protective enzyme activity while the MDA content and cell membrane permeability were significantly decreased.