| In grape production,the application of gibberellin can not only enlarge grape fruit,but also promote the formation of seedless grape fruit.In grape production,the application of gibberellin can not only enlarge grape fruit,but also promote the formation of seedless grape fruit.Streptomycin promotes the denuclearization of pitted grape fruits.At present,there are few studies on the seedless formation process and mechanism of grape fruits induced by gibberellin and streptomycin.Therefore,this paper observed the seedless formation process and analyzed the physiological mechanism of grape fruits of ’Shine Muscate’ induced by applying 25 mg/L GA3 and 200 mg/L SM before flowering.It provides theoretical basis for further research on the molecular mechanism of seedless formation and improving fruit quality.The main results are as follows:Streptomycin promotes the denuclearization of pitted grape fruits.The main results are as follows:1.The observation and study on flower morphology,pollen activity and stigma receptivity of ’Shine Muscat’ grape showed that the anther was the base drug and the anther color changed regularly.There was no pollen adhesion on stigma and pollen tube germination at the emergence stage and the initial stage of separation.Pollen grains were approximately spherical,and most germination pores were 3-pore grooves.From complete separation stage to full flowering stage,a large number of pollen grains were scattered,and pollen vitality was divided into 60.7%,73.2%and 80.3%.With the development of grape flower,the color of stigma of grape flower shows a regular trend of change.Mastoid cells on stigma surface first take on cell shape,and then the surface is full and smooth.At maturity,mastoid cells are long and cylindrical,and then gradually shrieve and disintegrated.The stigma acceptability shows a change rule of "none-stronger-stronger-stronger-none".The nucellar tissue within the ovule is well developed at the exudation stage and the early separation stage,a few pollen tubes can be seen in the style at the complete separation stage,a large number of pollen tubes can be seen at the beginning and full flowering stage to guide the tissue into the style through the stigma and into the ovule through the micropyle,and the development of the primary endosperm nucleus can be seen at the fruit setting stage.The results indicated that the complete separation stage was the initiation time of cleistogamy in ’Shine Muscat’ grape.2.Effects of GA3 and SM treatments on reactive oxygen species in the flowers of’Shine Muscat’ grape.The pollen activity of grape decreased,the length of pollen tube became shorter,and the activities of SOD,POD and CAT in grape flower organs decreased.In the control group,dormant zygotes appeared at 3d after anthems,two-cell proembryos appeared at 3d after anthems,heart-shaped embryos appeared at 9d after anthems,spherical embryos appeared at 12d after anthems,and mature embryos developed at 15d and 22d after anthems.After gibberellin induction,the endosperm of the embryo sac began to degenerate at 9d after anthesis,and the embryo sac was empty at 15d after anthesis.After SM induction,the embryo sac began to degenerate at 9d after anthesis,and the endosperm of the embryo sac was completely degenerate at 12d after anthesis.After mixed treatment with the two regulators,the embryo sac and endosperm cells began to degenerate at 6 days after anthesis,and the embryo sac was empty at 12 days after anthesis.Embryo abortion occurred after anthesis in all treatment groups.The seedless rate of grapes in all treatment groups was higher than that in control group,and different degrees of embryo abortion occurred after treatment.3.After GA3 and SM induction,the content of soluble sugar in grape flower increased,while the content of soluble protein and starch decreased.In the control group,polyamine content continued to increase,Put content first increased and then decreased after plant growth regulator induction,and was higher than the control group at 48h,Spm and Spd were significantly lower than the control group,(Spm+Spd)/Put continued to decrease,and was lower than the control group at 48h.After exogenous plant growth regulators,the contents of GA3,IAA and ABA in grape flowers increased first and then decreased,and the contents of GA3 and IAA were significantly lower than those in control group,while the content of ABA was significantly higher than that in control group.The ratio of(GA3+IAA)/ABA continued to decrease,and the decrease was the most significant in the mixed treatment group,indicating that there was a certain relationship between endogenous polyamines and flowering hormones induced by exogenous plant growth regulators,and the ratio of(GA3+IAA)/ABA and(Spm+Spd)/Put was closely related to embryo embryo development.Through the observation and physiological mechanism analysis of grape seedless formation induced by exogenous plant growth regulators,it was found that endogenous hormones and polyamines played an important role in the process of seedless formation.25 mg/L GA3+200mg/L SM was the best agent to induce grape seedless formation. |
