Study On Genetic Relationship Of Ulmus And The Radiation Induced Mutation

Elm is the general name of genus Ulmus L. It is one of the most important tree species which used as timberland and shelter forest in plains, saline-alkali soil and barren lands in China. There are thirty genus Ulmus species in the world and twenty-five species and six variants in China. Ulmus plants distribution area and Elm germplasm resources are decreasing every year. Originally hilly groud and sandy which belonged to Ulmus are serious of artificial destruction such as estrepement, overgrazing. It is significance to avoid Ulmus plant resources being further damaged, better protected of elm species in China and breeding new cultivars for landscaping.This study investigate the distribution of Ulmus in Heilongjiang, Shandong, Zhejiang and climate drier’s Gansu province. The genus Ulmus are investigated, collected, analyzed and evaluated. Secondly morphological markers and ISSR molecular markers are used to study the genetic relationships among all Ulmus. Finally in order to obtain excellent ornamental characteristics and resistant plants, U. pumila seeds are radiated by60Co-γ. This research will lay a foundation of Ulmus breeding and landscape application. The main results are as follows:1)70%percent of Ulmus plants were collected and investigated which belonged to three sections and two series. It was included all Ulmus germaplasm resources in Heilongjiang among others there was two endemic species. Ulmus species and cultivars which distributed in Shandong, Zhejiang and Gansu province were also collected and investigated. Analsis hierarchy process(AHP) was used to evaluate Ulmus germaplasm. U.pumila L.、U.laevis Pall.、U.glaucescens Franch.、U. macrocarpa planch.、U. parvifolia Jacq.、U. pumila L. cv."jinye "and U.pumila L. cv."tenue" were excellent materials in landscape applications. U.pumila L.、U.laevis Pall.、U.propinqua Koidz.、 U. taihangshan-ensis S.Y Wang、U.americana L.、U.castaneifolia Hemsl.were excellent materials in economic applications. U.densa Litv.、U.lamellosa T.wang were excellent materials resistance to drought and salinity. U.glaucescens Franch., U. macrocarpa planch., U.lamellosa T.wang were excellent materials in fruit oil production. U.laciniata Schneid.、U. taihangshan-ensis S.Y Wang and ’TY’ were high resistance to insects. Among them leaves of U.laciniata Schneid. had less pests except for Alternatus, so it was a good tree species in Alternatus controllable area.’TH’ was not only had beautiful leaf color but also had less pests, so it was an excellent materials in landscaping.2) Ulmus species and varieties which collected from Heilongjiang and Shandong province were classified based on morphological traits. Twenty-eight morphological characteristics were encoded as classified information which including ten qualitative binary characters, ten qualitative polymorphic characters and eight quantitative characters. Q cluster showed that Ulmus varieties and half-sib families were in the same group. The results of cluster were similar to the traditional classification except siberian elm. The independence of each character was presented by R cluster. Twenty-eight morphological characteristics had independent significance in the evolution of Ulmus. The principal component analysis showed that first five principal components accumulative contributor ratio amounted to71.02%, and some representative characters which could be used in classification, such as fruit characters and leaf characters.3) The optimal ISSR-PCR reaction system were built.11ISSR primers which had clear bands and polymorphisms were select from93primers.97bands were produced after using11ISSR primers,86bands were polymorphic(88.66%). The range of genetic similarity coefficient was from0.5490to0.9216. The genetic similarity coefficient of siberian elm068and siberian elm061were the biggest (0.9216). The genetic similarity coefficient of siberian elm34and G6were the smallest (0.6863). The result of ISSR clustering was similar to the traditional classification in Ulmus. U. pumila L. cv.sp was far away from other cultivars. The genetic relationships of U. pumila L. cv.’Pyramidalis’ and genus Ulmus were relatively close. The Genetic similarity coefficient of U. pumila L. cv.’jinye’ and U. parvifolia Jacq was relatively high. Half-sib families and U.pumila were clustered in the same group. U.pumila L was close to U.pumila L. cv.’tenue’, U.laevis Pall, U. pumila L. cv.’pendula’. Ulmus species were divided into three sections. Cultivar varieties and U.pumila L. were in the same clustering. U.americana L.and U.laevis Pall were belonged to the same clustering in section Ⅱ. The relationship of U. macrocarpa planch, U.laciniata Schneid and U. parvifolia Jacq was relatively close. U.davidiana Planch. U.propinqua Koidz and U.densa Litv were belonged to the same clustering in section III.4) The optimal60Co-γ lethal dose of U.pumila seeds was50Gy.60Co-γ had negative effection on young plant growing, the more dose, the more damage. Low dose(30-70Gy) had positive effection on plant height and plant fresh weight.60Co-γ increase growing of Lateral root, but inhibit main roots. Radiation between30-90Gy was helpful to the growth of plants. Radiation between30-100Gy could produce mutation on ornamental traits.60Co-γ can also effect phenophase of Ulmus, Radiation between30-50Gy was useful to leaves growth. leaves were inhibited when radiation was over50Gy. Lenticel shape was ellipse when radiation was30Gy and Lenticel shape became almost round when radiation was over30Gy.5) Low radiation dose can enlarge the stigma of white elm, which has stimulatory effect to the development of stigma. While high radiation dose made the development dysplasia, acted inhibition effect to the development of stigma. The ratio of pollen axis and equator was decrease following the increase of preirradiation dosage. The ornamentation of pollen exine were fine quasi reticular with no radiation, the reticular became sparse and the size of small particles became smaller and spare following the increase of radiation dosage. There were some effects on leaf ultrastructure of elm under radiation with different dose, the changes to leaf ultrastructure was obviously at radiation dose of70to100Gy. The structure of chloroplast became intumesced, double-layer membrane disappeared and thylakoid fused; the double-layer membrane of mitochondria was disappear and occurred vacuolar degeneration and cristae fragmentation; the nuclear membrane was also disappeared. 6) There were negative correlation between chlorophyll content and radiation, radiation dose; the value of chlorophyll a/b has a jump at70Gy and showed on leaves with yellow-white colour; when the radiation dose was100Gy, there were extremely significant difference of chlorophyll a/b between treatments and control and showed on leaves with red colour; the activities of SOD and POD increased at first and then decreased following the increase of radiation dose. The activities of CAT has the top value at the peak with radiation dose of30Gy and then decrease, there were a steadily and slightly rises at radiation dose50to100Gy.