| Solanum melongena L.is a popular vegetable crop in China.After long-term breeding,the genetic background of eggplant is becoming narrower,and many resistance genes of Wild Eggplant resources are lacking.Distant hybridization is an effective way to improve the resistance of eggplant.Previous studies have shown that there are reproductive barriers in eggplant hybridization with related species,and there are significant differences in the number of seeds per fruit in interspecific hybridization,which may be related to the biological characteristics of pollination and fertilization.At present,the mechanism of this phenomenon is not clear in the interspecific hybridization of eggplant.Therefore,the study on the mechanism of difference in fertilization process of interspecific cross combinations is helpful to further understand the reasons for the significant difference in the number of seeds per fruit in interspecific cross combinations,and is of great significance to enrich the theoretical basis of eggplant cross breeding.In this paper,the hybrid compatibility of cultivated eggplant 177,SHF and wild relatives(Solanum aethiopicum)53 and Y11 was analyzed by pollen morphology observation,pollen vigor detection,fruit setting rate comparison in spring and autumn,and number of seeds per fruit statistics.The pollen tube behavior and double fertilization process were observed.Finally,Transcriptome sequencing was performed on ovaries of 177? at 0 day after pollination,177?at 4 days after pollination and 177? at 6 days after pollination,177×53 at 4 days after pollination,177×53 at 6 days after pollination,177×Y11 at 4 days after pollination and177×Y11 at 6 days after pollination.The differences among different combinations during double fertilization were analyzed,and the internal mechanism of differences was discussed.The main results are as follows:1.The pollen grains of cultivated eggplant 177 and SHF are similar to those of wild relatives 53 and Y11 in morphology(the equatorial view is long ellipse,the polar view is trilobate circular,and the pollen extine decoration type is graininess),but the pollen grains ofcultivated eggplant are significantly larger than those of wild relatives;hybrid can set fruit and produce seeds.However,there were differences in fruit setting rate between self-crossing and cross-crossing combinations.The fruit setting rate of self-crossing combinations was higher than that of cross-crossing combinations,but it was greatly affected by the environment.The fruit setting rate of cultivated eggplant was higher than that of female parent in autumn,and that of Wild Eggplant in spring was higher than that of autumn.In spring and autumn,the fruit setting rate of 177?was 74.59%,84.44%,177×Y11 was 28.80%,55.37% and 17.9%,and that of 177×53was 17.93%,53.78% respectively.177 as female parent had significantly higher fruit setting rate in spring and autumn than hybrid combination,and 177 had higher fruit setting rate and better stability in spring and autumn.There were differences in seed number of single fruit between self-crossing and hybrid combinations,and the number of seeds per fruit of self-crossing was significantly more than that of hybrid combinations.2.The pollen germination and tube growth of self-crossing and cross combinations were normal,and the growth rates of self-crossing and cross-crossing pollen tubes were basically the same.All combinations germinated on stigma 2 hours after pollination.177? 、 177×53 、177×Y11、SHF?、SHF×53、SHF×Y11 reached the base of the style at 24 h after pollination and 48-72 hours after pollination,they all reached ovule nearly.53?、53×177、53×SHF、Y11?、Y11×177、Y11×SHF reached the base of the style at 16 h after pollination and 24-48 hours after pollination,they all reached ovule nearly.3.177?、177×53、177×Y11 was found to be close to the nucleus and polar nucleus of oocyte 4 days after pollination,and double fertilization began.On the 6th day after pollination,sperm cells fused with oocyte,and SHF was consistent with that.53?、53×177、53×SHF、Y11?、Y11×177、Y11×SHF was found that sperm cells fused with egg cells to form zygotes 4days after pollination.Complete synergids could still be seen 2 days after 177? combination pollination.4.By transcriptome sequencing the ovaries of ovaries of 177? at 0 day after pollination,177? at 4 days after pollination and 177? at 6 days after pollination,177×53 at 4 days after pollination,177×53 at 6 days after pollination,177×Y11 at 4 days after pollination and177×Y11 at 6 days after pollination.,83870 unigenes were obtained.Seven samples were compared with NP blank control,AP1774 D vs AP534 D,AP1774D vs APY114 D,AP1776D vs536 D,AP1776D vs AP1776 D,APY116D vs APY116 D,346 DEGs,2559 DEGs,8207 DEGs and 2131 DEGs were obtained respectively.The time-series expression patterns of these DEGs were analyzed.It was found that there were differences between self-crossing and cross-crossing time-series expression patterns,and the time-series expression patterns of the two hybrids were similar.The differentially expressed genes in hybrid combinations were mainly concentrated in the “kinesin complex”,“ATP dependent micro tubule motor activity,plus end directed ”"and“ATP dependent micro tubule motor activity”.The differentially expressed genes in self-crossing combinations were mainly concentrated in the“nucleobase-containing compound metabolic process”,“cellular aromatic compound metabolic process”,“cellular macromolecule metabolic process”,“Nitrogen compound metabolic process”,“heterocyclic metabolic process” and “nucleic acid metabolic process”.KEGG enrichment of DEGs revealed that DEGs were mainly concentrated in plant signal transduction,plant pathogen interaction,ubiquitin-mediated protein hydrolysis,and MAPK signal transduction which may be involved in double fertilization.5.The expression patterns of 12 genes were analyzed by q-PCR.TRINITY＿DN21699＿c0＿g1,TRINITY＿DN2934＿c0＿g1 and TRINITY＿DN12370＿c0＿g1 were down-regulated after 4 and 6 days of pollination.TRINITY＿DN11326＿c0＿g1 and TRINITY＿DN25513＿c0＿g1 were up-regulated after 4 and 6 days of pollination.TRINITY＿DN29891＿c2＿g3 and TRINITY＿DN22701＿c0＿g1 were up-regulated by self-pollination and down-regulated by hybridization after 4 or 6 days of pollination.TRINITY＿DN27571＿c11＿g1 was up-regulated by self-pollination,down-regulated by hybridization and down-regulated by 6 days after pollination.TRINITY＿DN29103＿c1＿g1 was down-regulated by self-pollination and up-regulated by hybridization 4 days after pollination,and up-regulated by 6 days after pollination.TRINITY＿DN37493＿c0＿g1 was up-regulated by self-pollination and down-regulated by hybridization after 4 days of pollination,and up-regulated after 6 days of pollination.TRINITY＿DN1996＿c0＿g1 was up-regulated by self-pollination and down-regulated by hybridization after 4 days of pollination.After 6 days of pollination,down-regulated by self-pollination and up-regulated by hybridization.TRINITY＿DN30426＿c4＿g2 only AP536 D was up-regulated 6 days after pollination,while other combinations were down-regulated 4 and 6 days after pollination.These 12 differentialgene expression trends were basically consistent with RNA-Seq results,indicating the reliability of transcriptome data. |
PDF Full Text Request