| Paeonia is the only genus of Paeoniaceae.Its germplasm resources are widely distributed and the genetic traits are rich.Paeonia can be divided into three groups : Sect.Moutan,Sect.Paeonia and Sect.Onaepia.The main way to cultivate new varieties of peony is to use the abundant germplasm resources in the genus for intra-group and inter-group cross breeding.At present,the main hybridization between Sect.Moutan and Sect.Paeonia.In recent years,certain results have been achieved in carrying out intergroup crosses of the Paeonia in China.However,in the practice of breeding distant hybrids of the Paeonia,problems such as large number of progeny populations,variable performance of traits and the existence of false hybrids often arise.Therefore,after obtaining the progeny population,it is necessary to carry out selection and identification of hybrid authenticity according to the breeding objectives.In this study,204 distant hybrids were studied from four Intersectional hybrid combinations:(1)HL: P.lactiflora ‘Hangshao’×P.qiui;(2)ZL: P.lactiflora ‘Zi Fengyu’×P.qiui;(3)SZ:P.lactiflora cv.×P.rockii;(4)ZC: P.rockii‘Wenxian Fen’×P.veitchii.The superior plants of these hybrids were screened using hierarchical analysis;on this basis,the superior plants of the four combinations were authenticated using a combination of morphological and EST-SSR molecular identification methods.The main research and results are as follows:1.The progeny of the four combinations of flowering hybrids were investigated and analyzed for field traits,and the evaluation indexes were screened and a hierarchical evaluation system was established according to the selection objectives of different combination types.(1)In the HL combination,two superior plants were screened out of 51 flowering progeny,HL-11 and HL-23,both of which can be used in cut flowers and garden flowers;(2)In the ZL combination,five superior plants were screened out of 31 flowering progeny,ZL-6,ZL-37,ZL-45 and ZL-46(4 plants)can be used in cut flowers and garden flowers,and ZL-48 can be used in garden flowers;(3)In the ZL combination,five superior plants were screened out of 31 flowering progeny,ZL-6,ZL-37,ZL-45 and ZL-46(4 plants)can be used in cut flowers and garden flowers,and ZL-48 can be used in garden flowers.(3)In the SZ combination,13 superior plants were selected from 109 flowering progeny,SZ-21,SZ-45,SZ-47,SZ-77,SZ-80,SZ-82,SZ-85,SZ-102,SZ-113,SZ-115,SZ-121,SZ-124,SZ-132(13 plants)can be used in cut flowers and garden flowers.(4)In the ZC combination,four superior plants were selected from the 13 flowering progeny,ZC-13,ZC-18,ZC-21 and ZC-23(4 plants)can be used in garden flowers.2.Using phenotypic characters such as leaf shape,disc texture and degree of atrial coating,flower type and fruiting ability as morphological markers for authenticity identification of superior plants,and the appearance of phenotypic characters of the parents or the absence of fruiting ability as the basis for identification,the 24 superior plants and the related traits among their parents were analyzed for differences and authenticity identification.The 24 superior plants and the related traits between their parents were analysed for differences and authenticity,and 13 plants were initially identified as true hybrids.(1)the two superior plants screened by the HL combination did not have parent-specific phenotypes and were not identified as true hybrids because they had no parent-specific phenotypes and were fruit-bearing.(2)Among the five superior plants screened by the ZL combination,only ZL-6 showed broad leaf shape and lobed leaflets,which had parental characteristics;ZL-37,ZL-45,ZL-46 and ZL-48(four plants)had no fruiting ability.These five plants were all tentatively identified as true hybrids.(3)Among the 13 superior plants screened by the SZ combination,SZ-121 and SZ-132(2 plants)showed broad leaves and lobed leaflets with parental characteristics;SZ-21,SZ-45,SZ-102 and SZ-124(4 plants)had no fruiting ability;these 6 plants were tentatively identified as true hybrids.85,SZ-113 and SZ-115(7 plants)had no parent-specific phenotypes and were fruit-bearing.(4)Among the four superior plants screened by the SZ combination,ZC-18 and ZC-23(2 plants)had lobed leaflets,which were lobed or deeply lobed,and had parental characteristics,and ZC-18 was not capable of setting fruit;ZC-13 and ZC-21(2 plants)had no parental specific phenotypes and were fertile.The above 13 plants have identification reference in leaf shape or fruiting ability,and are tentatively designated as true hybrids.However,they did not show parental traits in disc texture and degree of atrial coating,and flower type,and even segregation of traits in flower type was observed.In order to avoid the instability of traits due to environmental effects,the results of morphological identification need to be combined with EST-SSR molecular markers for further identification.3.In this study,29 pairs of polymorphic EST-SSR primers from the transcriptome of peony and peony were used to screen for polymorphism among the parents of the 4combinations,and the results showed that 11 pairs of primers were polymorphic in the parents of the 4 combinations at the same time,namely primers PLE2,PLE12,PLE20,PLE22,PLE23,PLE31,PLE33,PLE39 Using these 11 primer pairs,PCR amplification was performed on the 24 superior plants selected from the four combinations mentioned above,and the capillary electrophoresis results showed that a total of 20 of the 24 superior plants had parent-specific bands and were identified as true hybrids,with the following results:(1)HL combination: HL-11 and HL-23(2 plants)were pseudo-hybrids;(2)ZL combination: ZL-6,ZL-37,ZL-45,ZL-46 and ZL-48(5 plants)were true hybrids;(3)SZ combination: SZ-21,SZ-45,SZ-47,SZ-77,SZ-80,SZ-82,SZ-85,SZ-102,SZ-113,SZ-115,SZ-121,SZ-124,SZ-132(13 plants)were true hybrids;(4)ZC combination: ZC-18 and ZC-23(2 plants)were true hybrids,and ZC-13 and ZC-21(2 plants)were false hybrids.The results of morphological identification and EST-SSR molecular marker identification showed that 20 of the 24 superior plants were identified as true hybrids,of which 13 were identified as true hybrids by both methods,and 7 were identified as true hybrids only by EST-SSR molecular markers.4.In summary,this study established a hierarchical evaluation system according to the selection objectives of different combination types,and a total of 24 superior plants were screened from the progeny populations of the four combinations,which can be applied in cut flowers or garden flowers.In addition,this study provided clear morphological markers and primers for EST-SSR markers,which are suitable for authenticity identification of progeny of intergroup crosses of the genus Paeonia.20 of the 24 superior plants were identified as true hybrids and 4 as false hybrids.These methods are helpful to shorten the breeding process and improve the breeding efficiency. |
