ObjectiveThere are three subfamilies of the PEBP gene family:FT-like, TFL1-like and FT/TFL11-like. We have known that FT/TFL1-like genes are the core regulation hubs in reproductive regulation network in angiosperms. Only the undifferentiated FT/TFL1-like subfamily in conifers was suggested play important roles of reproduction, growth rhythm and dormancy process. However, the knowledge of its expression profiles and the expressional regulation by different environmental factors about the FT/TFL1-like genes in conifers are still limited. This may result in some inaccurate speculation about the role of its related expression mechanism.

MethodIn this study, we isolated two FT/TFL1-like genes form Chinese pine (Pinus tabuliformis), named as PtTFL1 and PtTFL2. The expression level of these genes in different tissues, the developing male cones and female cones in different stage, the needles during the dormancy and dormancy release, the response to relative warmer temperature and under different day length and light were studied.

ResultThe results showed that PtTFL1 was specifically expressed in pollen and nearly no expression in other tissues. But the PtTFL2 was very broadly expressed and significantly expressed in the bud tissue than other tissues. But both of two genes were not significantly expressed in the rapidly proliferating callus; in addition, the analysis of the expression level of PtTFL2 in different environments was found. PtTFL2 accumulated in buds and conifers during the dormancy period and decreased when dormancy release; under the condition of relatively high temperature but not enough to break dormancy, the expression of PtTFL2 was significantly inhibited, which was similar to that of far red light treatment.

ConclusionIt can be seen that PtTFL1 may be related to pollen maturation process in the reproductive development process of Pinus tabuliformis, but PtTFL2 may be involved in more other developmental regulation, both of them are not necessary to maintain cell activity. The autumn environmental conditions are very conducive to the accumulation of PtTFL2 in male, female cones and needle, this expression profile of it is highly correlated with dormancy. However, PtTFL2 expression pattern is too sensitive to temperature and the expression patterns of male, female cones and needles are more likely to result in response to temperature, indicating that PtTFL2 itself probably is only a temperature response and signal transmission factor and regulated by far-red light under short day rather than related to the regulation of cone development or be sufficient to maintain dormancy. This study provides important data for further understanding the function of FT/TFL1-like gene in important developmental processes, such as reproductive and dormancy of Chinese pine, and its expression regulation by different environmental factors.