Collection And Evaluation Of Germplasms And Identification Of Core Germplasms In Torreya Grandis

Torreya grandis is a species of Torreya in Taxaceae, in which Torreya grandis cv. Merrillii, an elite variant, is the only variety cultivated on a large commercial scale. But there are a variety of variations within the species in the wild natural population. As an important economic trait, seeds vary greatly in shape, size, physico-chemical characteristics, main nutrients and taste and there exist some individuals that are superior or close to Torreya grandis cv. Merrillii in comprehensive traits or quality. In order to develop superior resources, utilize their potential in genetics and breeding, and break the phenomenon that only Torreya grandis cv. Merrillii has been under cultivation for more than one thousand years, investigation, collection and evaluation of Torreya grandis germplasm resources were conducted in main distribution areas. The thiesis is a summary of the work done, the details of which are as follows:1. Physico-chemical traits of 110 single tree-based germplasm resources collected from such distribution areas of T. grandis as Zhejiang, Anhui , Fujian, and Jiangxi were analyzed in terms of length, diameter and weight of the seed with and without peel as well as protein and fat contents that affect the post-processing taste. It has been revealed that the seed size varied greatly and 3 individuals had a fat content and 9 ones had a protein content higher than or close to those of Torreya grandis cv. Merrillii. The result has paved the way for the multi-purpose exploitation of the resources.2. For a total of 213 germplasm resources collected including 103 ones previously collected (out of which 142 have seed data), morphological data of their leaves and seeds were analyzed, based on which two primary germplasm pools with a number of 51and 19 each were constructed with the help of SPSS. ANOVA suggested that the primary germplasm pools constructed could well represent original germplasms collected. With a newly established SRAP protocol and a well established ISSR protocol, the individuals of the primary germplasm pools were analyzed at the DNA level, the data of which were analyzed with NYSTS 2.0 according to DICE and clustered according to UPGMA. Finally, two core germplasm pools were constructed, with one having 15 individuals from the seed data-based primary germplasm pool and the other having 8 individuals from the leaf data-based primary germplasm pool. Both core pools have no individual overlapped and form a core germplasm pool composed of 23 individuals, which accounts for 10.8% of original germplasm resources collected. A comparison conducted between the primary and core germplasm pools in Na, Ne, H, I and PPB% showed that the core germplasm pool conserved more than 89% genetic diversity of the primary one, which means that the core germplasm pool constructed was a good representative of the primary one. The technical protocol for indentification of core germplasms could be applied to other non-timber species.3. Some special individual seedlings of T. grandis were discovered in the field, which are 1.75 times of the annual height of and over 2 times of the annual radical diameter of common seedlings in T. grandis. With a SRAP protocol, the phylogenetic relationship among 8 samples of 6 species of Torreya including the special Torreya individual (T. grandis var. Merrillii, T. yunnanensis, T. fargesii, T. grandis var. jiulongshanensis var. nov., T. nucifera, T. graendis cv. Dielsii, T. jackii and the special Torreya individual) has been studied in combination with analysis of variance (ANOVA) in leaf shape index. It has been revealed that 8 samples of 6 species including the special Torreya individual could be categorized into 4 groups and the special Torreya individual is grouped with T. grandis var. jiulongshanensis var. nov. and T. jackii; the special Torreya individual is close to T. jackii in terms of leaf morphology; and there is most significant difference among the species tested in leaf shape index, with the special Torreya individual significantly different from other samples. It is inferred that the special Torreya individual is a hybrid between T. grandis and T. jackii. This result has laid a foundation for the development of this special individuals in production and breeding in shortening the period of vegetative growth.4. A comparison among different male individuals of T. grandis from the same producing area in leaves, inflorescence, weight of pollen from a single inflorescence, etc. showed that there existed variations with a maximal variation coefficient found in pollen weight, which reached 55.29%, flowering lasted for 7 days, which means early, mid- and late flowering pollen donators could be selected, and the difference in pollen morphology is not obvious among the male trees from different locations or the same place. The results showed that diversity of male trees made an important contribution to diversity of female ones, which has paved the way for selection of superior male trees.