Genetic Diversity Study Of Ceiba Spp

Ceiba spp.is a good gardening and greening species which is widely planted in Southern China and gradually introduced into other provinces.Currently,the planting of Ceiba speciosa in China is facing two main problems.First,the official name of Ceiba spp.is obscure since there are at least two names for it and it is also obscure as to the categories and classifications.According to records in history,China has introduced at least two different kinds of plants under the classification of Ceiba which shared the same name of Ceiba spp..Second,there are huge differences in florescence and shapes between each single plant of Ceiba spp.,making it hard to form a group beauty of a landscape.Therefore,this paper studies the florescence,shapes,and genetic relationships of Ceiba spp.so as to provide theoretical and technological reference for the application,combination with other plants,specific germplasm exploration,and directed breeding in the future.The main research results are as follows:1.The author monitored phenological phases of 172 Ceiba spp.in Guangzhou in two consecutive years.Based on the method Dafni described on flowering rhythm,the author monitored and recorded main events,including 7 phenological phases.By monitoring and analyzing the records,the author found in a same phenological phase,the Ceiba spp.would basically enter the phenological phase in two different periods of time.For example,late July to late August,and late September to late October are the two periods when the buds of Ceiba spp.would grow quickly,which demonstrated that there might be two or more kinds of Ceiba spp.in China.By analyzing the 7 phenological phases of Ceiba spp.,the variance of the year,and the phenotypic variation coefficient,it was found that except that during the early period of blossom,the variance of the year showed little difference?P>0.05?,in other periods,the differences were very distinct either in single plant or in different years?P<0.01?.The variances of the year may be resulted from the weather,while the differences in each single plant showed the variety in phenological phases of Ceiba spp..2.According to the identification key in Gibbs about Ceiba,the author selected 23morphological characters including the color of the petal apex to investigate 110 Ceiba spp.in terms of morphology.After analyzing the coefficient of variation,the author found the morphological characters all showed huge differences,with the color of lower stamen tube and the blossom largest at 135.54%and spiniform at 93.55%.The smallest coefficient is leave edge at12.66%.If dividing the 23 morphological characters into 6 main components,the length of styles,the color of stamen tube affiliations,the lengths of upper stamen tube,leaflet and petiole contribute most,while the width of flower,the length of lower stamen tube,the width of leaflet and leaf edge contribute least.Analyzing from the perspective of morphological cluster,if Euclidean distance at 15.5is set as the cluster threshold,we can divide the 110 Ceiba speciosa into 4 groups:I,II,III and IV.By referring to the identification key in Ceiba,the author found that the 4 groups are all related to C.insignis,C.ventricosa,C.lupuna and C.speciosa under C.insignis agg.,and they show a transitional connection.For example,the SD33 and HR06 in group I have the transitional characters in C.lupuna and C.speciosa as the petal apex is dark red and has dark red stripes.3.The author concludes a ISSR-PCR 10ul reaction system which is feasible to Ceiba spp.by ISSR-PCR system optimization.The systems include 10×buffer(with Mg²⁺),2mMdNTPs,50ng DNA template and 10pmol primer.After screening 100 ISSR general primers,14 primers with clear and polymorphic were used for amplification analysis.A total of 133 bands were amplified by the 14 primers,of which 113 were polymorphic fragments.8.1 primers were amplified by each primer by average and the percentage of polymorphisms was 84.96%.The ISSR cluster analysis of the Ceiba spp.showed that the genetic distance of the 172germplasms was between 0.0462-0.6277.Dividing the genetic distance at 0.245,these samples could be divided into six branches of A,B,C,D,E and F,of which A and B were the two largest branches,including 80 and 82 samples respectively,meanwhile C,D,E,F contain 3,5,1 and 1 samples respectively.4.Comparing the results in morphological cluster analysis and ISSR cluster analysis,they were highly consistent and the morphological differences in single plant of Ceiba spp.were caused by genetic variance.The correlation between the morphological characters and the results of ISSR clustering was analyzed.It was found that there was a good correlation between ISSR clustering and 4 morphological characters:the shape of stem,stem spines,the color of the stamen tube appendages and the florescence,while the other morphological characters were scattered in different branches,and there was no obvious correlation.As the results of florescence phenology and morphological clustering,local Ceiba spp.is derived from at least 4 species of the genus and their hybrids.