Soil bacteria augment Arabidopsis photosynthesis by decreasing glucose sensing and abscisic acid levels in planta.
Photosynthesis is regulated by environmental factors as well as endogenous sugar signals. Whereas light-driven sugar biosynthesis is essential for terrestrial organisms, as well as belowground microflora, whether and how soil symbionts regulate photosynthesis has yet to be reported. Here, we show that the plant growth-promoting soil bacterium Bacillus subtilis GB03 augments photosynthetic capacity by increasing photosynthetic efficiency and chlorophyll content in Arabidopsis. Mechanistic studies reveal an elevation of sugar accumulation as well as the suppression of classic glucose signaling responses, including hypocotyl elongation and seed germination, with exposure to GB03. Compared with wild-type plants, two Arabidopsis mutants defective in hexokinase-dependent sugar signaling exhibit increased photosynthetic capacity, which is not further enhanced with GB03 exposure. Overlap in sugar/ABA sensing is observed in GB03-exposed plants, with a reduction of ABA-biosynthetic transcripts as well as downstream metabolite levels in leaves. Moreover, exogenous ABA abrogates GB03-triggered increases in photosynthetic efficiency and chlorophyll content. These results demonstrate that certain rhizobacteria elevate photosynthesis through the modulation of endogenous sugar/ABA signaling, and establish a regulatory role for soil symbionts in plant acquisition of energy.
Zhang
Huiming
H
Departments of Chemistry/Biochemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA.
Xie
Xitao
X
Departments of Chemistry/Biochemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA.
Kim
Mi-Seong
MS
Departments of Chemistry/Biochemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA.
Kornyeyev
Dmytro A
DA
Departments of Chemistry/Biochemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA.
Holaday
Scott
S
Departments of Chemistry/Biochemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA.
Paré
Paul W
PW
Departments of Chemistry/Biochemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA.
D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000378:metabolism; D001412:Bacillus subtilis / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D018525:Germination; D005947:Glucose / Q000378:metabolism*; D018546:Hypocotyl / Q000378:metabolism; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D012988:Soil Microbiology; D013559:Symbiosis; D014835:Volatilization
D029681:Arabidopsis Proteins; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D000040:Abscisic Acid; D005947:Glucose