Regulatory Mechanism of the Photosynthetic Pathway in Dwarfed Upland Cotton (Gossypium hirsutum L.)

[Objective] Here, we examined the mechanism of the photosynthetic pathway in dwarfed upland cotton (Gossypium hirsutum L.). [Methods] The upland cotton dwarf line LA-1 and the near-isogenic line LH-1 were used as research materials. We screened for dwarf-related differentially expressed genes at protein and mRNA levels by applying the isobaric tags for relative and absolute quantitation method in combination with LC-MS/MS quantitative proteomic technology and quantitative reverse-polymerase chain reaction. The difference in the photosynthetic abilities between the two materials were detected using physiological and biochemical methods. [Results] An analysis on the differential expression of proteins encoded by photosynthetic system elements revealed that PsbO, PsaE, PsaH, PetF-1 and PetF-2 were down-regulated, while PetC and delta were up-regulated in LA-1. The expression trends of the mRNA levels were the same as at the protein levels, except for those of the delta gene. The net photosynthetic rate, stomatal conductance and transpiration rate in LA-1 were lower than those LH-1, but the intercellular CO₂ concentration was not significantly different after budding. This indicated that the non-stomatal factor led to a decreased net photosynthetic rate in LA-1. Chlorophyll fluorescence detection revealed that the actual photosynthetic efficiency and potential photochemical activity of photosystem II in LA-1 were significantly decreased, while non-photochemical quenching was significantly increased. [Conclusion] The dwarfism of LA-1 is related to the photosynthetic pathway, and the results lay a foundation for exploring key dwarf-related genes and the molecular basis for dwarfism in upland cotton.