Study On Fertility Of Triploid Rose As Pollen Parents

The Rosa Genus has a very high ornamental value,and are popular among people because of their large flowers,bright colors and easy cultivation and application.Contrary to what is commonly considered to be “triploid infertility”,it has been found in previous studies that the triploid ancient rose ‘Chun Shui Lv Bo’ is not only fertile,but also has a high seed setting rate.In order to reveal the cause of the fertility of triploid rose plants,this study studied the fertility and genetic mechanism of triploid rose,aiming to provide theoretical support for the application of the triploid Rosa Genus in rose breeding.In this study,eight triploid rose were observed for palynological characteristics and pollen particle size analysis.Then,the 94 F1 progeny plants of the 3 hybrid combinations were tetraploid rose as the female parent,and the triploid and diploid were used as the pollen parent respectively.The morphological characteristics of 94 F1 progeny plants were observed,genetically analyzed and ploidy tested to explore the genetic characteristics of triploid traits.Finally,the chromosomal behavior during the meiosis of the triploid ancient rose ‘Chun Shui Lv Bo’ and triploid modern rose ‘Knock Out’ was observed.The specific results are as follows:1.Multiple comparisons of pollen polar axis lengths showed that the coefficient of variation of the polar lengths of the other seven triploids pollen was higher than that of diploid and tetraploid,except for Rosa Multiflora Thunb.The pollen particle size analysis showed that the particle size of the Rosa Multiflora Thunb.pollen conformed to the normal distribution,indicating that only one ploidy pollen was produced;the pollen grain size of the other seven triploids showed a bimodal distribution,indicating that it produced two ploidy of pollen.The frequency of 2n pollen in triploids was higher,with ‘Knock Out’ being the highest,reaching 78.07%,followed by ‘Hu Zhong Yue’(71.05%)and ‘Chun Shui Lv Bo’(64.9%).2.The traits of 94 F1 generations of three combination were observed,and two excellent single plants were screened.According to genetic analysis,it was found that except for plant height,F1 plants with different degrees of super-parentality appeared in each trait.Some F1 plants showed negative super-parentality;using flow cytometry to detect F1 ploidy which tetraploid as female parent,triploid ‘Chun Shui Lv Bo’ and ‘Knock Out’ as pollen parents.The results showed that the offspring were all tetraploid,which indicated that the triploid rose provides 2n pollen,and the 2n male gamete has fertility.3.In order to explore the reasons for the fertility of the triploid rose ‘Chun Shui Lv Bo’male gametes,the pollen mother cells were observed by compression,and it was found that mid-term I,the late I,the middle II,the late II,and the latest II,were found.Legging chromosomes,also found chromosome bridges,parallel spindles(56.25%)and spindles at an angle of 120 °(18.75%).The meiotic products were found to have a triad(6.65%),a quintile(24.21%),and a meiotic product with one or two microspores.The lagging chromosomes,triads,and quintiles in meiosis cause diploid pollen particle size to vary,resulting in different ploidy pollen.The appearance of parallel spindles is the cause of 2n pollen production.There are complete genomes in 2n pollen,so the fertility is good and can proproduce the offspring.