| Torreya grandis is an evergreen tree species of Torreya in Taxaceae, in which only Torreya grandis“Merrillii”, an excellent nut landrace native to China and formed through vegetative propagation of anexcellent natural variant, is cultivated on a large commercial scale. In recent years, increasingdevelopment of Torreya grandis “Merrillii” industry has led to grafting on trees of Torreya grandis anda short supply of pollen from Torreya grandis. In addition, previous utilization of Torreya grandis at alow level and felling of non-fruting male trees have resulted in damage to natural Torreya grandispopulations to a certain extent, which has had an impact on population genetic diversity in Torreyagrandis. Abundant genetic diversity is not only an expression of adaptability of a species but also amaterial basis of breeding and genetic improvement. Since Torreya grandis has a very high economicvalue, previous studies have focused on Torreya grandis “Merrillii” with no systematic studies onTorreya grandis. But male trees of Torreya grandis are the paternal parent of Torreya grandis “Merrillii”.Therefore, this paper systematically studies genetic diversity of male and female Torreya grandissaparately and that of Torreya grandis as a whole based on an optimized SRAP analysis protocol, in thehope of providing a theoretical basis for subsequent conservation and utilization of resources. The mainresults are as follows:1、With natural populations distributed in such main distribution areas of T. grandis as ZhutaVillage of Chunan County and Taihuyuan Village of Lin’an City, Zhejiang Province as well as Xiaorongand Qiaoshan villages of Huangshan City, Anhui Province,81male samples from such populationswere analyzed with35pairs of SRAP primers. As a result, a total of530loci were amplified with apercentage of polymorphic loci (PPL%) of76.6%, a Nei’s gene diversity (H) of0.2900, a ShannonInformation index (I) of0.4482, and a total genetic diversity (Ht) of0.2723. In addition, it was foundthat82.5%of genetic variation resided within a population, with no significant difference betweenpopulations and the geographical distance and genetic distance were not significantly correlated. Withthe genetic diversity index as an indicator for evaluation, Xiaorong population exhibited at the highestlevel of genetic diversity (h=0.2952and I=0.4421), followed by Zhuta (h=0.2381and I=0.3352), andQiaoshan (h=0.1879and I=0.2791) populations, with the lowest genetic diversity found in Taihuyuanpopulation (h=0.1661and I=0.2476). 2、86female samples from the same populations were analyzed with26pairs of SRAP primers. Asa result, a total of404loci were amplified with a PPL of81.68%, a Nei’s gene diversity (H) of0.2949, aShannon Information index (I) of of0.4545, and a total genetic diversity (Ht) of0.2880. In addition, itwas found that89.11%of genetic variation resided within a population, with no significant geneticdifference between populations and the geographical distance and genetic distance were notsignificantly correlated. With the genetic diversity index as an indicator for evaluation, Qiaoshanpopulation exhibited at the highest level of genetic diversity (h=0.2908and I=0.4418), followed byXiaorong (h=0.2800and I=0.4306), and Zhuta (h=0.2736and I=0.4194) populations, with the lowestgenetic diversity found in Taihuyuan population (h=0.1820and I=0.2773).3、At the species level,167male and female samples of Torreya grandis from the same populationswere analyzed with35pairs of SRAP primers. As a result, a total of546loci were amplified with a PPLof81.68%, a Nei’s gene diversity (H) of0.3247, a Shannon Information index (I) of of0.4949, and atotal genetic diversity (Ht) of0.3217. In addition, it was found that95.37%of genetic variation residedwithin a population, with no significant genetic difference between populations and the geographicaldistance and genetic distance were not significantly correlated. With the genetic diversity index as anindicator for evaluation, Xiaorong population exhibited at the highest level of genetic diversity(h=0.3218and I=0.4872), followed by Zhuta (h=0.3208and I=0.4844), and Qiaoshan (h=0.2963andI=0.4527) populations, with the lowest genetic diversity found in Taihuyuan population (h=0.2876andI=0.4331).The results showed that Torreya grandis was rich in genetic diversity and both male and femaleTorreya grandis made an important contribution to the genetic diversity of Torreya grandis as a whole.With the increasing and fast development of Torreya grandis industry nowadays, how to conserve,utilize and develop genetic resources of Torreya grandis deserves reflection. We hope that our resultscan provide some useful information. |
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