TY  - JOUR
A1  - Wang, Meng
A1  - Li, Panpan
A1  - Ma, Yao
A1  - Nie, Xiang
A1  - Grebe, Markus
A1  - Men, Shuzhen
T1  - Membrane sterol composition in Arabidopsis thaliana affects root elongation via auxin biosynthesis
JF  - International journal of molecular sciences
N2  - Plant membrane sterol composition has been reported to affect growth and gravitropism via polar auxin transport and auxin signaling. However, as to whether sterols influence auxin biosynthesis has received little attention. Here, by using the sterol biosynthesis mutant cyclopropylsterol isomerase1-1 (cpi1-1) and sterol application, we reveal that cycloeucalenol, a CPI1 substrate, and sitosterol, an end-product of sterol biosynthesis, antagonistically affect auxin biosynthesis. The short root phenotype of cpi1-1 was associated with a markedly enhanced auxin response in the root tip. Both were neither suppressed by mutations in polar auxin transport (PAT) proteins nor by treatment with a PAT inhibitor and responded to an auxin signaling inhibitor. However, expression of several auxin biosynthesis genes TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 (TAA1) was upregulated in cpi1-1. Functionally, TAA1 mutation reduced the auxin response in cpi1-1 and partially rescued its short root phenotype. In support of this genetic evidence, application of cycloeucalenol upregulated expression of the auxin responsive reporter DR5:GUS (beta-glucuronidase) and of several auxin biosynthesis genes, while sitosterol repressed their expression. Hence, our combined genetic, pharmacological, and sterol application studies reveal a hitherto unexplored sterol-dependent modulation of auxin biosynthesis during Arabidopsis root elongation.
KW  - Arabidopsis thaliana
KW  - auxin
KW  - auxin biosynthesis
KW  - cycloeucalenol
KW  - CPI1
KW  - sitosterol
KW  - sterol
Y1  - 2021
U6  - https://doi.org/10.3390/ijms22010437
SN  - 1422-0067
VL  - 22
IS  - 1
PB  - MDPI
CY  - Basel
ER  -