Development And Application Of EST-SSR Markers For Cunninghamia Lanceolata

Cunninghamia lanceolata is one of the most important fast-growing timber tree in southernof China. In order to develop effective molecular markers, for the genetic diversity analysis andmolecular assistant breeding in C. lanceolata, the transcriptome sequences of C. lanceolata wasalso used to exploit SSR sites and markers. The polymorphic EST-SSR markers were used forgenotyping of150Chinese fir clones. Based on LD analysis and population structure, theassociation analysis between EST-SSR markers and3important phenotypic traits were furtherperformed using TASSEL GLM. These results of this study are summarized as follows:(1) Based on the analysis of growth traits and wood properties of150Chinese fir clones,thewood basic density is mostly between0.3123g.cm-3and0.3454g.cm-3, and the heart sapwoodratio between1.9824and3.0652,and the DBH between21.22-27.02cm. The variation andcharacteristics of the growth and wood properties of C. lanceolata between the clones andbetween the11populations were analyse. Result indicates that there are great differences in DBHand basic density between the clones of the C. lanceolata, while an insignificant difference wasfound in heart sapwood ratio;there are great differences in DBH and heart sapwood ratio betweenthe populations of the C. lanceolata, while an insignificant difference was found in basic density.(2)83248sequences were screened by using MISA software to search for SSR motifs.There were8628SSRs present in7129sequences, the frequency of SSRs was8.36%.Trinucleotide repeats were the most abundant (56.88%). According to these sequences,105pairsof EST-SSR primers were designed. Through PCR and sequencing,30pairs of EST-SSR primerswith polymorphism were isolated.(3) The number of alleles of these primers with polymorphism varied from2to6, and themean number was2.47alleles per locus. The polymorphism information content (PIC) valueranged from0.0134to0.4752, with an average of0.3074.The results of POPGENE showed thatthe average effective number of alleles was1.5350and Shannon’s index of polymorphicinformation was0.5120. Genetic structure analysis showed that the150clones were grouped into4subpopulations. There were1SSR loci associated with the density.All the results indicated that the developed SSR markers from EST sequences will be ofimportant application value in genetic analysis and molecular breeding of C. lanceolata.