The Transcriptome of Cunninghamia lanceolata male/female cone reveal the association between MIKC MADS-box genes and reproductive organs development

Abstract

AbstractBackgroundCunninghamia lanceolata(Chinese fir), a member of the conifer family Cupressaceae, is one of the most popular cultivated trees for wood production in China. Continuous research is being performed to improveC. lanceolatabreeding values. Given the high rate of seed abortion (one of the reasons being the failure of ovule and pollen development) inC. lanceolata, the proper formation of female/male cones could theoretically increase the number of offspring in future generations. MIKC MADS-box genes are well-known for their roles in the flower/cone development and comprise the typical/atypical floral development model for both angiosperms and gymnosperms.ResultsWe performed a transcriptomic analysis to find genes differentially expressed between female and male cones at a single, carefully determined developmental stage, focusing on the MIKC MADS-box genes. We finally obtained 47 unique MIKC MADS-box genes fromC. lanceolataand divided these genes into separate branches. 27 out of the 47 MIKC MADS-box genes showed differential expression between female and male cones, and most of them were not expressed in leaves. Out of these 27 genes, most B-class genes (AP3/PI) were up-regulated in the male cone, whileTM8genes were up-regulated in the female cone. Then, with no obvious overall preference forAG(class C + D) genes in female/male cones, it seems likely that these genes are involved in the development of both cones. Finally, a small number of genes such asGGM7,SVP,AGL15, that were specifically expressed in female/male cones, making them candidate genes for sex-specific cone development.ConclusionsOur study identified a number of MIKC MADS-box genes showing differential expression between female and male cones inC. lanceolata, illustrating a potential link of these genes withC. lanceolatacone development. On the basis of this, we postulated a possible cone development model forC. lanceolata. The gene expression library showing differential expression between female and male cones shown here, can be used to discover unknown regulatory networks related to sex-specific cone development in the future.