Cytological studies of F1 hybrid sterility between Lagerstroemia speciosa and Lagerstroemia indica'Ebony Embers'
[Objective]The progeny of Lagerstroemia speciosa and Lagerstroemia indica'Ebony Embers'are highly sterile,In order to analyze the reasons for the sterility of their offspring.[Method]In this experiment,L.indica'Xiaoxiang Huaxiu'was used as the material which was the F1 hybrid of L.speciosa as the female parent and L.indica'Ebony Embers'as the male parent,by paraffin section microscopy to observe the growth and development process of the stamens and pistils of male,and the mature pollen grains in the accumulation of soluble sugar,starch,lipid;and the contents of soluble sugar,starch,free proline in different growth stages were determined.[Result]1)The sterility of L.indica'Xiaoxiang Huaxiu'was the result of combined male and female sterility.Pollen grains exhibit aberrant characteristics including shriveled appearance,deformities,and size variations,leading to the majority of pollen grains being unable to germinate.2)Compared with L.speciosa and L.indica'Ebony Embers',abnormalities occurred in the F1 generation during meiosis,specifically,some chromosomes were not arranged normally to the center of the equatorial plate during meiosis,and the chromosomes segregation was not uniform,developing into abnormal dyads,micronucleated dyads,micronucleated tetrads,pentads and sexads,and most pollen nuclei dissolve during the binucleate pollen grains stage.Mature pollen grains were mostly deformed without contents and couldnot sprout,the germinable pollen grains were 2n pollen grains.3)The megaspore atrophies and dissolved in the tetrad stage,and formed a cavity with a few embryo sac traces in the later stage.4)The contents of soluble sugar,starch and free proline in F1 generation's flower bud were lower than those in the parent's flower bud of the same period.Lipid,soluble sugar and starch accumulation was not observed in most pollen.[Conclusion]The abnormal behavior of chromosomes leads to the appearance of abnormal tetrads and the disintegration of nuclei in the period of binucleate pollen grains are the main reasons for pollen abortion.Atrophy and disintegration of megaspore during tetrad is the main cause of female sterility.
Lagerstroemia speciosaLagerstroemia indica'Ebony Embers'hybrid sterilitynutrients in pollencytology
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