The Comparative Studies On Brugmansia’s Nectar Components Antibiotic Activity And Culturable Nectar Dwelling Microorganism Diversity

Nectar is liquid secreted by higher plants floral organs under normal conditionswith specific ecophysiological function related with plant pollination andreproduction. Nectar production is an innovative step in the course of angiospermevolution. Higher plants with nectar in their fertilization process can be an effectiveuse of animals as a medium, accurate delivery of genetic material to improve theplant genetic diversity. But the importance of nectar for different breeding types(self-compatibility and self-incompatibility) is not the same. In addition tocarbohydrates, as well as proteins, amino acids, polyphenols, lipids, organic acids,alkaloids and volatile organic compounds and other secondary metabolites, nectaralso has symbiotic microorganisms, including bacteria and fungi. Nectar microbialcommunities have unique physiological functions. Nectar composition dynamicchanges and the activity of particular components closely associated with the floralorgan characters, pollinator types and others. Therefore the characteristics of nectarmicrobial communities are directly related to plant breeding system type, andpossessed a kind of species-specific.The main scientific problems to be solved in this study are:1, the nectarmicrobial composition of different plant breeding systems;2, nectar microorganismsorigin, exogenous（including pollinator-borne）or endogenous;3，Whether nectarantibiotic mechanisms are different in plants with breeding systems. Materials andmethods to be adopted include:1, two closely related species of Brugmansia,Brugmansia suaveolens (BS)(self-incompatible) and the horticultural species B.’DrSeuss’(BDSS)(self-compatible) are selected as the experimental plant materials,Datua stramonium (DS)(self-compatible) as a control;2, using selective mediumand the methods of molecular identification to identify the cultured microbialspecies in nectar and the endophytes in stalk, determine the origin of nectarmicroorganisms;3, the conventional methods for determining nectar microbialdensity, morphological analysis and preservation;4, using chemical and enzymaticactivity analysis methods for the determination of the main components of nectar and antibacterial ingredients which are generally believed to be involved in nectarantibiotic mechanisms, correlated with the nectar microbial density to informed itsantibiotic role.The main results of this study include:1, identified BS, BDSS, DS majorfungal and bacterial species, a total of68bacterial species, belonging to21families;27fungal species, belonging to14families;2, BS, BDSS and DS nectar containsexogenous and endogenous bacteria, part of the exogenous bacteria were introducedby pollinators. BS and BDSS nectar fungi are completely exogenous.Self-incompatible BS nectar fungus were completely from pollinators;3, it is stillunclear that the chitinase, glucanase, xylanase, hydrogen peroxide, etc possessantibiotic function in the nectar we tested, except for polyphenols. A general view ofnectar broad-spectrum antimicrobial ingredient-hydrogen peroxide in BS, BDSSdoes not exist. The hydrogen peroxide antibiotic mechanism may not widespread inplants;4, there are some differences in nectar antibacterial mechanism in plants withdifferent breeding systems.This study laid the initial foundation for further studies on the floral nectardwelling microorganisms ecophysiological function, floral nectar antibioticmechanisms in different breeding systems. The endophytes’ role in floral nectar，polyphenols antibiotic mechanisms and the comprehensive nectar antibioticmechanism are worthy follow-depth study.