Research Of Pollen Germination Characteristics And Differentially Expressed Proteins Of Carya Illinoensis

Carya illinoensis is a deciduous tree that is originated in Northern Mexico and SouthernUnited States. The fruits and tree trunks are of high value, which are often praised byconsumers. In this study, we evaluated four different varieties of Carya illinoensis pollenswithrespect to germination and tube growth, storage characteristics and physiological as well asbiochemical characteristics of pollen during storage process, and differentially expressedproteins during pollen germination. Key findings are summarized as follow:1. Several factors affected germination and tube development of Carya illinoensis pollenunder in vitro culture conditions. The optimal culture time and temperature was24h and25-30℃. Germination and tube growth of pollen were inhibited when the pH value was over5.5; the concentration of sucrose was over20-25%; the concentration of boric acid is over0.03%; and the concentration of PEG-4000was over15%.2. Storage temperature and time greatly influenced pollen vitality. In general, the degree ofimpact was lower with lower storage temperature and shorter storage time.It was evident thatpollen cannot be sorted at room temperature at which its viability was markedly reduced. the4℃storage condition can be applied to collect pollen of male flowers powdering earliervarieties and artificial supplementary pollination for female flowers flowering later varieties,-20℃storage condition can be used to save pollen for artificial supplementary pollination nextyear, the storage effect of pollen vitality of-70℃is the best which can be used for pollengermplasm resources preservation.3. Under the tested four storage temperatures, the physiological and biochemical indexesvaried considerably with increasing storage time.Compared with room temperature and4℃,storage at-20℃or-70℃led to less accumulation of MDA in pollen, enhanced activity of SODand POD, and reduced pollen membranous peroxide and damage to membrane system.Moreover, storage at-20℃or-70℃also led to high soluble protein and soluble sugar content,enhancedfrost resistance, and ultimately translated to maintaining high pollen vitality.4. Some revisions are made in making2-D electrophoresis of proteins. It was found thatthe optimal method to extract proteins was phenol-methanol/ammonium acetate precipitation.When1500μg protein was separated using pH4-7IPG strip, protein spots were clearly resolvedand detected. The matching rate of2-DE maps of different varieties of Carya illinoensis wasover70%. The number of differentially expressed proteinswere as follows,3in Pawnee,9inMahan,10in Western, and3in‘Zhongshan25’. The differences in the detectedprotein numbersmay be related to differences in pollen germination rates. There were16new protein pointsappeared and4protein points disappeared. Expression of three proteins points were raisedin the germinated pollen map of Carya illinoensis.The differences of protein expressed in2-DE mapsbetween mature pollen and germinated pollen were not detected. Therefore, we concluded thatmature pollen use stored protein to supply for pollen germination and pollen tube growth.