A BRC1-modulated switch in auxin efflux accounts for the competition between Arabidopsis axillary buds
Fig 7
The middle region of the PIN1 hydrophilic loop confers strigolactone sensitivity.
(A) Fluorescence intensity of basal plasma membranes of xylem parenchyma cells of stems expressing GFP-tagged PIN variants after 6 h mock treatment or treatment with 5 µM GR24. For each stem, the mean fluorescence intensity represents the mean of the 5 brightest membranes for that stem, n = 14−24. (B) Fluorescence intensity of basal plasma membranes of xylem parenchyma cells for stems expressing GFP-tagged PIN variants of each genotype. For each stem, the mean fluorescence intensity represents the mean of the 5 brightest membranes for that stem, n = 28−37. (C) Representative images for dataset presented in panel B. PIN1:GFP visible in green and chlorophyll autofluorescence in magenta. (D) Bulk stem auxin transport in basal inflorescence stem internodes of plants at terminal flowering for the genotypes indicated. Transport was determined as accumulation of radiolabeled auxin in the basal 5 mm of 15 mm stem segments after 16 h incubation with apical 22 nM 3H-IAA, n = 56−68. (E) Relative expression of BRC1 as measured by qRT-PCR in Col-0, SIP1pin1, smxl678, and SIP1pin1smxl678 in small buds (>2.5 mm, presumed inactive) and big buds (<5 mm, presumed active). Buds were harvested from cauline nodes of whole Arabidopsis plants. Each point represents a biological replicate, with the larger point and bar, representing the mean and associated standard error. Each biological replicate corresponds to the expression level measured in at least 10 pooled buds. Statistical comparisons were made on log transformed data, using two-way ANOVA with Bonferroni correction. In all panels, stars or different letters indicate statistically significant differences at p < 0.05 from custom contrasts or pairwise comparison, respectively. Unless otherwise stated, statistical analysis involved a multi-level model with Bonferroni corrections. Data and scripts of simulations underlying this figure can be found at https://doi.org/10.17863/CAM.120831.
doi: https://doi.org/10.1371/journal.pbio.3003395.g007