| Rosa rugosa is a dominant species of the shrub communities in the sandy coast and dune ecosystems.Otherwise,it is an important germplasm resource for genetic breeding of ornamental and essential oil roses.Rosa rugosa f.plena is an widely used variety for production of essential oils,food,medicine,cosmetics,and gardening.Flowering is an important stage in plant growth and development,and flowering-related traits and genes have always been hotspots in plant evolutionary biology and breeding practice.Based on next generation transcriptome sequencing,studies on genetic differentiation of R.rugosa populations of different provenances in similar cultivation conditions can reveal the adaptive evolution pattern of flowering-related genes in R.rugosa with eliminating the influences of provenance environment on gene expressions.The results are expected to provide evidences for understanding adaptive evolution of R.rugosa across its native,cultivated and invasive regions and evolution of flowering regulatory candidate genes.We use thirteen R.rugosa populations of different provenances as a research system to reveal adaptive genetic differentiation of these populations based on flowering regulatory gene expressions.The R.rugosa populations for transcriptome sequencing are belonging to three groups,the Chinese wild R.rugosa（CWR）,Chinese cultivated R.rugosa（CCR）and European wild R.rugosa（EWR）.All the 13 populations have been cultivated in three common gardens located in Jinan and Taian of Shandong Province,China.We screened out 183 candidate genes related to photoperiod pathway,GA pathway,autonomous pathway and vernalization pathway,and 55 candidate genes of MADS-box gene family from the transcriptome sequences.Further we analyzed differential expression of candidate genes,correlation between gene expressions and environmental factors,clustering heat map,GO and KEEG enrichment of differential expression genes,molecular evolution of key flowering regulatory genes such as GI,CO,FT genes and MADS-box gene family.The main results are as below.1.The thirteen R.rugosa populations belonging to three groups formed an interconnected and distinct genetic differentiation pattern based on the candidate genes related to five flowering regulatory pathways.Latitude was seemed to be the main environmental factor driving genetic differentiation of the flowering regulatory candidate genes.2.A conservative pathway similar to the GI-CO-FT flowering regulation of model plant Arabidopsis thaliana was identified in the candidate genes of R.rugosa with annotation function.The genetic differentiation of GI,CO and FT candidate genes in R.rugosa has been analyzed.The identified conserved domains were similar to the respective sequences in other plants.The phylogenetic tree showed that the GI,CO and FT candidate genes of R.rugosa are closely related to the respective genes of R.chinensis.3.There were 55 candidate genes of MADS-box gene family identified in R.rugosa.Among them,the key genes of the ABCD model involved in the formation of flower morphology,such as SEP,FUL,APE,and AG,showed the characteristics of multiple copies.The key genes that regulates flowering time,such as SOC1,also showed the characteristics of multiple copies.The related homologous genes in R.rugosa were more than those in A.thaliana.As an environmental factor that influencing climatic conditions,latitude may affect adaptive evolution of flowering-related candidate genes in R.rugosa by affecting light and temperature.The GI and CO genes between species may be relatively conservative and can be used to study adaptive differentiation between species.Compared with A.thaliana,there might be more sophisticated and complex regulation patterns in flower organ morphology and flowering regulation of R.rugosa.It is suggested that further research on underlying evolutionary mechanisms of R.rugosa flowering-related genes and verification of important function genes. |
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