Study On Male Sterility And Hybridization Progenies Of Ulmus Pumila D33

In order to explore the mechanism of pollen abortion in male sterile of the U.pumila D33,solve the difficult problem of elm hybridization,create a new elm germplasm resource and cultivate even better hybrid offspring.From 2016 to 2017,used an infertility experiment at the nursery of the Third Branch Plant of Hebei Agricultural University.Male sterility D33 and common clones such as HLS1?Heilongshan No.1?;Y3?Yanshan No.3?,and Y4?Yanshan No.4?were used as test materials,observed the changes in the external morphology of the flower buds of elms,and paraffin section method was adopted from the perspective of cytology and study its development process.The full-sib families of the two-year-old trees which D33×Y1?U.pumila?,D33×B28?U.laciniata?,D33×D2?U.davidiana Planch.var.japonica?,D33×B18?U.davidiana?,and D33 half-sib families were used as test materials.Through the field investigation and indoor analysis,studied the seedling growth,fruit characteristics,progeny identification,photosynthetic characteristics,fluorescence characteristics and correlation analysis of five families.The main results were as follows:?1?It was found that the discovered the cause of microspore abortion by observing the external morphology anatomy and microstructure of male flower sterility D33 and flower bud development of HLS1,Y3,and Y4.Due to the abnormal development of the tapetum,it disintegrates prematurely,causing the anther to shrink and fail to form normal pollen.The ratio of gibberellin and GA3/IAA in male sterile D33 was the lowest,which was significantly lower than other elm clones.?2?Male sterile D33 can bear normal fruits after crossing with the different elms clones,but there were obvious differences in seed setting rate and seedling emergence rate because of the different father.Through the fitness test of leaf phenotypic characteristics of the hybrid offspring of D33 and U.pumila'Jinye',it can be seen that the fitness between the actual number and the theoretical number meets the separation rule of1:1.SSR test results confirmed that all seedlings were hybrids.?3?The mean height and average ground diameter of the five families were significantly different.The D33×B18 families had the highest growth rate and the D33half-sib families had the worst growth.The coefficient of variation of leaf morphological of the D33×B28 families was significantly higher than other families.There was a highly significant positive correlation between seedling height and ground diameter.There was a highly significant positive correlation between leaf perimeter,leaf length,leaf width,and leaf area.?4?The chlorophyll a content,chlorophyll b content and total chlorophyll content of D33×D2 and D33×B18 families were significantly higher than other families.The chlorophyll a content/chlorophyll b were significantly greater in the D33×B28,D33×B18and D33 half-sib families than other families.?5?The variation trend of photosynthetic parameters and fluorescence parameters in5 families was not consistent between June and September.?6?There was no significant difference in the maximum photochemical efficiency?Fv/Fm?and potential activity of PSII?Fv/Fo?in five families.There was a significant positive correlation between Fv/Fm and Fv/Fo in five families.There was a significant negative correlation between NPQ and qP in 5 families.In summary,the cause of the abomination of microspores in male sterile D33 was due to the abnormal development of the tapetum,and the tapetums disintegrate prematurely and cannot form normal pollen.The gibberellin content and the ratio of GA₃/IAA were the lowest,which may be the main reason why filaments did not grow.After male sterile D33 hybridized with different elms,normal fruits could be produced,but the seed setting rate and seedling emergence rate were significantly different due to the difference in male parents.The tests showed that the offspring obtained were all hybrids.There were significant differences in growth,morphology,chlorophyll content,photosynthetic characteristics,and fluorescence characteristics among the different families,which different families obtained different hybrid elm.The D33×B18 families had higher growth and diameter growth than other families.The coefficient of variation of leaf morphological of the D33×B28 families was significantly higher than other families.