Studies On The Characteristics And Classification Of Several Allium Landraces

Allium L.is an important health care vegetable in China,which has important edible and medicinal values.Cultivation of Allium vegetables in China has a long history and there are lots of Allium landraces,but the research on them is relatively weak,and there are also controversies in the classification of them.In this study,18 Allium landraces were collected(most of which were landraces in Zhejiang Province),which were used as materials to investigate the morphological traits and determine the quality traits.Meanwhile the cluster analysis was carried out based on morphological traits and principal components,and ITS sequence analysis was used to explore their kinship.All the studies will lay solid foundation for the development and utilization of local Allium resources,and provide a reference for Allium classification research.The main results are as follows:1.The content of dry matter,soluble sugar,soluble protein,pyruvic acid in 18 cultivars was significantly different,especially pyruvic acid.Among storey onions,the content of dry matter and soluble sugar was relatively higher,while pyruvic acid was relatively lower.Among bunching onions,the content of soluble protein was relatively higher,while dry matter and soluble sugar was relatively lower.Among shallots,the content of soluble protein was relatively higher and dry matter and soluble sugar was generally between the first 2 variants.The pyruvic acid content of most cultivars of the latter 2 species(variants)was higher than that of the first variant.The amount of essential amino acids,non-essential amino acids and the sum of them of shallots were higher than that of bunching onions repectively.The amino acid content of storey onions was much lower than that of the first 2 species(variants).The coefficient of variation among cultivars within each species(variant)in scallions was greater than that of shallots,and the variation among storey onions was less.17 kinds of amino acids and 1 basic amino acid(gABA)could be detected in 18 cultivars,including 8 essential amino acids.Most cultivars had relatively higher Thr,Tyr and Ala content,while had lower Lys,Gly,and His content.Shollots had more contents of the essential amino acids and non-essential amino acids than bunching onions,and the amino acid content of storey onions was much lower than that of shallots and bunching onions.2.The headspace gas chromatography mass spectrometry method was used to determine the kinds and contents of volatile components in 18 Allium landraces,one green onion cultivar,and one onion cultivar.The determination results showed that the proportion of sulfide in volatile components was different whether in different species(variants)or in different cultivars(9~56%).A total of 31 kinds of sulfides were detected,of which alkyl substituted sulfides accounted for 61.33%.Among the components of alkyl substituted sulfides,propyl sulfides accounted for the highest proportion(48.53%),while allyl sulphide accounted for the lowest proportion(0.76%).There were significant differences in the kinds and contents of sulfides among Allium species and cultivars.The most sulfides of shallots,welsh onion and onion were monosulfides,while storey onions and bunching onions were disulfides.Benzothiazole was the only sulfide that could be detected in all 20 cultivars.3.A field survey of 9 quantitative traits and 21 qualitative traits of 18 Allium cultivars revealed that all the quantitative traits and qualitative traits had a high degree of diversity among different germplasms.All the investigated characters and 4 principal components were used for cluster analysis respectively,and the cluster results were basically the same.The cluster results divided all the germplasms into 5 groups in the smallest branches,namely A.ascalonicum L.(bolting)group,A.ascalonicum L.(non-bolting)group,A.fistulosum L.var.caespitosum Makino(bolting and blooming)group,A.fistulosum L.var.caespitosum Makino(non-bolting and non-blooming)group and A.fistulosum L.var.viviparum Makino group repectively.4.The analysis results of 20 Allium cultivars using the ITS sequence alignment method showed that the total length of ITS sequence of 20 Allium species was between 613-616 bp,and the GC content of all of them was 46%.20 mutation sites including insertion,deletion and substitution were found in this study.A20,A4,A1 and A5 had a relatively large number of mutation sites,which was 18,17,12 and 10 respectively,while other cultivars had no mutations.The cluster results showed that A1,A4,A5 were closely related to A20(A.cepa L.),and A2,A3,A6~A18 and welsh onion(A19)were grouped together.5.Synthesizing the results of morphological characters classification and ITS sequence classification,our study supports the view that welsh onion,bunching onion and storey onion belongs to A.fistulosum L.But eight cultivars of shallot group were separated according to ITS sequence alignment,three of them were closely related to A.cepa L.,while the other five were close to A.fistulosum L.Therefore,it is considered that the origin and evolution of shallot are more complex,and more classification methods are needed for comprehensive judgment.