Fig 1.
Moderate pathogen stress accelerates reproductive development in Arabidopsis.
(A) Col-0 plants were inoculated with varying inoculum levels (Mock-106 spores/mL) of the fungal pathogen Fusarium oxysporum at the 6–8 leaf rosette stage and photographed 14 days later (14dpi). (B) Percentage of leaves showing symptoms at 14 dpi. (C) Percentage of plants that had bolted at 14dpi in each treatment. Data from B-C show mean and standard error from three biological replicates each containing 10 plants per treatment. Asterisk indicates statistically significant difference from mock treatment (P<0.05) using a Student’s t-test.
Fig 2.
Response of Arabidopsis natural ecotypes to F. oxysporum.
(A) F. oxysporum response was quantified by a disease score of 0–5 normalized to the disease score of the reference ecotype Col-0. Data shown are the mean and standard error of 3–40 plants per ecotype. Reference ecotype Col-0 and susceptible ecotype Ty-0 are shown in red. Ecotypes with disease scores significantly different (P<0.05) to that of Col-0 using a Student’s t-test were classed as resistant or susceptible. (B) Representative F. oxysporum- inoculated plants at 14 days post inoculation (dpi). Ty-0, Fei-0 and Sorbo are classed as susceptible, Col-0, Shakdara and Löv-5 are classed as intermediate and Tamm-27, Eden-1 and Löv-1 are classed as resistant. Enlarged photos of boxed leaves show vein clearing symptoms on highly resistant accessions Tamm-27 and Eden-1.
Fig 3.
Correlation between flowering time or latitude and Arabidopsis thaliana accession response to F. oxysporum.
(A) Flowering time was assessed as the number of days from germination until emergence of a 1cm bolt in ≥ 3 non-vernalized plants and was plotted against disease score for each of 83 natural accessions. The correlation using Pearson's product-moment correlation was significant (P = 0.003). (B) The disease score was plotted against latitude of the 83 natural accessions. The correlation using Pearson's product-moment correlation was significant (P = 0.005). Latitude information was obtained from https://easygwas.tuebingen.mpg.de/.
Fig 4.
The role of vernalization in the Arabidopsis thaliana response to F. oxysporum.
The effect of vernalization on flowering time and resistance to F. oxysporum in (A) A. thaliana natural accessions and (B) flowering-time and vernalization mutants. ‘Flowering time’ graphs display the number of days taken from germination to a 1 cm bolt. Data shown are mean and standard error from ≥3 plants per line. Plants that had not flowered at the conclusion of the experiment at 100 (A) or 80 (B) days post germination were given a value of 100 or 80. ‘Disease score’ graphs show mean and standard error of the disease score normalised to non-vernalized Col-0 (A) or non-vernalized ColFRISF2 (ColFRI). (B). Asterisks indicate significant difference (P<0.05) between disease score of vernalized and non-vernalized plants using a Student’s t-test. Data shown are mean and standard error from >8 plants per line. Blue bars show data from non-vernalized plants; red bars show data from vernalized plants. The experiment was conducted twice and similar results were obtained each time.
Fig 5.
Response to F. oxysporum in autonomous pathway mutants.
(A) F. oxysporum response (black bars) was quantified by a disease score of 0–5 normalised to the disease score of the reference ecotype Col-0. Disease score (black bars) show mean relative disease score at 14 days post inoculation (dpi) and standard error from at least 24 plants. Flowering time (white bars) was assessed as number of days taken from germination until emergence of a 1cm bolt. Plants that had not flowered at the conclusion of the experiment at 80 days post germination were given a value of 80. Data shown are mean and SE from ≥ 5 plants. Asterisks indicate significantly different values to WT (P<0.05) using a Student’s t-test. All mutants are in Col-0 background except those indicated (Ler). This experiment was conducted twice and similar results were obtained. (B) Representative F. oxysporum inoculated plants at 14 dpi. (C) Flowering time plotted against relative disease score for the 15 autonomous pathway mutant lines tested. Filled circles indicate Col-0 background, open dots indicate Ler background. The correlation using Pearson's product-moment correlation was significant (P = 0.0002). Experiments were conducted twice and similar results were obtained each time.
Fig 6.
Role of FLC in the F. oxysporum response.
(A) Flowering time data displayed are the number of days from germination to a 1cm bolt. Data shown are mean and standard error from ≥5 plants per line. Plants that had not flowered at the conclusion of the experiment at 80 days post germination were given a value of 80. Asterisk indicates significant difference to Col-0 (P<0.05) using a Student’s t-test. (B) F. oxysporum response was quantified by a disease score of 0–5 normalised to the disease score of the reference accession Col-0. Data show mean relative disease score at 14 days post inoculation and standard error from at least 24 plants. Asterisks indicate significantly different values to WT (P < 0.05) using a Student’s t-test. The experiment was conducted twice and similar results were obtained each time.
Table 1.
Number of fve-3 DEGs that are regulated by F. oxysporum.
Table 2.
Defense associated genes up or down-regulated >2 fold in fve-3 plants relative to WT plants.
Table 3.
Flowering-time genes that are responsive to F. oxysporum infection.
Fig 7.
GIGANTEA promotes susceptibility to F. oxysporum.
(A) Representative F. oxysporum- inoculated WT and mutant plants at 14 days post inoculation (dpi). (B) Percentage plant survival at 21 dpi. Data shown are mean and standard error from 3 biological replicates each containing 10 plants per line. Asterisks indicate significant difference relative to WT (P<0.05) using a Student’s t- test.
Fig 8.
Crosstalk between flowering-time regulators and F. oxysporum response in Arabidopsis thaliana.
Diagram represents a highly simplified schematic of the transition to flowering in Arabidopsis thaliana and the transcriptional affect of F. oxysporum on flowering-time genes relevant to this study. During long days, the mobile signalling component FT travels from the leaf to the meristem to initiate flowering. The FLOWERING LOCUS C (FLC) antagonizes the flowering transition by repressing FT and other floral integrators. In winter annuals, FLC transcription is activated by the plant-specific protein FRIGIDA (FRI). FLC transcription is down-regulated by vernalization (exposure to prolonged cold) or by members of the autonomous pathway at ambient temperatures, allowing flowering to occur under conducive conditions.