Genetic diversity and genetic structure of different types of natural populations in Osmanthus fragrans Lour. and the relationships with sex ratio, population structure, and geographic isolation.

Hongbo Zhao,Shaoqing Hu,Shuai Wu,Yiguang Wang,Yuanyan Zhang

doi:10.1155/2014/817080

Hongbo Zhao, Shaoqing Hu + Show 3 more

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https://doi.org/10.1155/2014/817080

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Abstract

Osmanthus fragrans Lour., an evergreen small tree, has the rare sexual system of androdioecy (coexistence of males and hermaphrodites), once with wide-spread natural distribution in the areas of the South Yangzi river basin. However, due to excessive human utilization, natural distribution became fragmented and the number and size of natural populations reduced sharply. With four different types of natural populations from the same region as research object, we aim to provide a comparative analysis on the relationships among genetic diversity, sexual system, population structure and size, and geographic isolation by ISSR. In genetic parameters of N e, H e, and I, the LQGC population had the highest value and the LQZGQ population had the lowest value. These indicated that LQGC population showed the highest genetic diversity, followed by QDH and JN population, and LQZGQ population exhibited the lowest genetic diversity. Genetic diversity in populations is closely related to population structure, reproduction mode, and sex ratio. However, there seems to be no obvious correlation between genetic diversity and population size. The results of AMOVA showed that genetic variations mostly occurred within populations. It indicates that no significant genetic differentiation among populations occurs, and geographic isolation has no significant effect on genetic diversity.

Highlights

IntroductionOsmanthus fragrans Lour. (Oleaceae), an evergreen small tree with the sexual system of androdioecy (coexistence of males and hermaphrodites in natural populations), is one of the most important ornamental plants and is a famous aromatic plant in China
Osmanthus fragrans Lour. (Oleaceae), an evergreen small tree with the sexual system of androdioecy, is one of the most important ornamental plants and is a famous aromatic plant in China
The amplification results of 15 Intersimple sequence repeat (ISSR) primers for 188 samples of four natural populations indicated high genetic diversity at the species level, and genetic variance mainly occurs within the population

Summary

Introduction

Osmanthus fragrans Lour. (Oleaceae), an evergreen small tree with the sexual system of androdioecy (coexistence of males and hermaphrodites in natural populations), is one of the most important ornamental plants and is a famous aromatic plant in China. The species has been utilized for many years and has a long history of cultivation (more than 2500 years) [1]. Osmanthus fragrans consists of four cultivar groups, namely, Aurantiacus, Albus, Lutes, and Asiaticus, with approximately 120 cultivars [1, 2]. The cultivars are mostly produced from artificial selection from natural populations and cultivar groups. Wild germplasm, which exhibits high morphological and genetic variation, is an important gene bank that could be useful for breeding improvement [3]. Excessive exploitation and utilization for natural resources have resulted in severe decline in the number and size of natural populations and damage and loss of the suitable habitats. Comprehensive analysis on genetic diversity of natural populations is necessary for the further utilization and protection of wild resources in this species

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