| Acer triflorum is a deciduous tree of the Sapindaceae family and is mainly distributed in the three provinces of Northeast China.As an autumn leaf tree species,it has high ornamental value.Due to the limitation of the distribution range and the deep dormancy characteristic of seeds,A.triflorum has not been cultivated on a large scale at present,the research on its physiological characteristics has not yet formed a system,and the value of its seed oil in edible and medicinal applications has not yet been developed.Through the study on the diversity of fruit-and-seed phenotypic traits,the genetic variation of A.triflorum can be understood deeply,reference for the collection and protection of germplasm resources,as well as breeding of improved varieties,can be provided.At the same time,in order to better realize the multi-purpose development of ornamental tree species and the sustainable development of nervonic acid raw material plants,it is necessary to explore more tree species with potential for development.It is of great significance to determine the characteristics of the seed oil of A.triflorum to evaluate whether it can be used as an ornamental and economic plant,that is,a source of nervonic acid.In this study,20 individual plants of A.triflorum in Liaoning and Jilin provinces of China were taken as the research object.Samaras were collected,whose morphological and qualitative traits were measured then.The diversity of fruit-and-seed phenotypic traits was analyzed,the variation rules were revealed.Correlation among the morphological and qualitative traits,as well as correlation among phenotypic traits and geographical and ecological factors,were clarified.The oil content and fatty acid composition of the kernel were determined,the diversity characteristics and variation rules of the seed oil were analyzed.The correlation among the characteristics of seed oil,as well as the correlation among characteristics,phenotypic traits and geographic ecological factors,were explored.Combined with the analysis results of fruit-and-seed phenotypic traits and seed oil traits,excellent germplasm of A.triflorum was screened,and a theoretical basis was provided for the protection and rational development of A.triflorum.The main findings are as follows:(1)There are extremely significant differences in seed-and-fruit phenotypic traits among individual plants of A.triflorum.The average coefficient of variation of the 19 phenotypic traits is 11.66%.The stability of morphological traits in seed-and-fruit phenotypic traits,especially the fruit morphological traits,is poor.The genetic differences of different individual plants and their adaptation to the environment lead to differences in the degree of variation among individual plants and among various traits.The morphology and quality of the seeds of A.triflorum are two relatively independent groups of traits.The correlation between the two types of traits is weak,and there are various correlations within each type of traits;except opening angle,connecting angle,fruit thickness and the seed size index,there is no significant correlation among most morphological traits and geographic ecological factors.Among qualitative traits,changes in geographical and ecological factors mainly affect the100-seed weight of samara.After principal component analysis,it was found that the variation of fruit morphology played a major role in the variation of seed-and-fruit phenotypic traits.From the results of cluster analysis,it can be seen that the fruit-and-seed phenotypic traits of A.triflorum are not clustered completely according to geographical location.The variation of phenotypic traits is discontinuous and unstable,and geographical and ecological factors are only part of the influencing factors,which shows that there are genetic differences between individual plants that are not affected by the environment,which makes our selection of excellent germplasm of A.triflorum more meaningful.(2)The oil content and fatty acid composition content of the kernel of A.triflorum are extremely different among individual plants.The average oil content is 36.31%.It is mainly composed of two types of saturated fatty acids [palmitic acid(C16:0)and stearic acid.(C18:0)] and six types of unsaturated fatty acids [oleic acid(C18:1),linoleic acid(C18:2),linolenic acid(C18:3),arachidonic acid(C20:1),erucic acid(C22:1),nervonic acid(C24:1)],the average total content of unsaturated fatty acids is 91.98%,and the average content of nervonic acid is 4.69%.Among the 13 seed oil traits,the largest coefficient of variation is the oil content(12.40%),the smallest is the total content of unsaturated fatty acids(0.47%),and the coefficient of variation of nervonic acid content is 6.37%.A.triflorum has the basis of being screened as high-oil germplasm resources,whose seed oil has stable and highly unsaturated characteristics.Compared with other traits,the stability of nervonic acid content is moderate,which shows that nervonic acid content in seed oil of A.triflorum can maintain a relatively stable level and A.triflorum has the potential to be screened for high nervonic acid germplasm.The oil content of the kernel of A.triflorum is a relatively independent trait,and there is no significant correlation with the content of fatty acid components,but there are various correlations among different fatty acid components;the characteristics of seed oil of A.triflorum.There are varying degrees of correlation among seed oil traits and some fruit-andseed phenotypic traits,while the correlation among the seed oil traits and the geographical and ecological factors is not significant.Compared with environmental diversity,genetic diversity plays a major role in the formation of seed oil traits.After principal component analysis,it was found that palmitic acid,oleic acid,linoleic acid,monounsaturated fatty acids,polyunsaturated fatty acids,linolenic acid,cis-11-Eicosenoicacid,erucic acid,and nervonic acid play major roles in the variation of seed oil.(3)After a comprehensive evaluation of the seed-and-fruit phenotypic traits,three individual plants of WN181,GGC215,and GGC260 with larger samaras and fuller kernels were selected.Based on the various seed oil traits,two individual plants of WN181(OC:40.35%,NA: 4.37%,EA: 11.80%)and WN190(OC: 38.44%,NA: 4.47%,EA: 12.15%)with“high OC and low EA” were selected;two individual plants of GGC260(OC: 48.52%,NA:5.07%,EA: 13.10%)and GGC215(OC: 38.21%,NA: 4.85%,EA: 12.70%)with “high OC and high NA” were slected.Integrating fruit-and-seed phenotypic traits and seed oil traits,three excellent germplasms of WN181,GGC260 and GGC215 that can be developed as oil and nervonic acid source tree species were finally screened out. |
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