Transcriptome analysis uncovering regulatory networks and hub genes of Populus photosynthesis and chlorophyll content.

Photosynthesis plays vital role in plant growth and development throughout its life, and it is influenced by environmental signals and circadian rhythms. We analyzed the transcriptome landscape of the two poplars progeny with contrasting photosynthesis rates at three times point (ZT4, ZT16, ZT22), constructed gene regulatory network that related to circadian rhythm and photosynthesis. We suggest that the differences in photosynthetic rate between the progenies may originate from plant endogenous circadian oscillators prepare poplar plants for photosynthesis by regulating photosynthesis-associated nuclear genes and carotenoid metabolism genes before dawn, genes associated with plant hormone signal transduction and transcription factor increase leaf size and stomatal movement, the influence of other core regulatory factors on chlorophyll accumulation. Furthermore, overexpression of candidate regulatory gene, AP3 (Potri.007G017000), induced leaf senescence and reduced the content of chlorophyll. These results demonstrated that many potential key regulators are integrated closely with chlorophyll content and photosynthesis.