Limits...
The F-box protein MAX2 contributes to resistance to bacterial phytopathogens in Arabidopsis thaliana.

Piisilä M, Keceli MA, Brader G, Jakobson L, Jõesaar I, Sipari N, Kollist H, Palva ET, Kariola T - BMC Plant Biol. (2015)

Bottom Line: Interestingly, max2 mutant plants showed increased susceptibility to the bacterial necrotroph Pectobacterium carotovorum as well as to the hemi-biotroph Pseudomonas syringae but not to the fungal necrotroph Botrytis cinerea. max2 mutant phenotype was associated with constitutively increased stomatal conductance and decreased tolerance to apoplastic ROS but also with alterations in hormonal balance.We conclude that the increased susceptibility to P. syringae and P. carotovorum is due to increased stomatal conductance in max2 mutants promoting pathogen entry into the plant apoplast.Additional factors contributing to pathogen susceptibility in max2 plants include decreased tolerance to pathogen-triggered apoplastic ROS and alterations in hormonal signaling.

View Article: PubMed Central - PubMed

ABSTRACT

Background: The Arabidopsis thaliana F-box protein MORE AXILLARY GROWTH2 (MAX2) has previously been characterized for its role in plant development. MAX2 appears essential for the perception of the newly characterized phytohormone strigolactone, a negative regulator of polar auxin transport in Arabidopsis.

Results: A reverse genetic screen for F-box protein mutants altered in their stress responses identified MAX2 as a component of plant defense. Here we show that MAX2 contributes to plant resistance against pathogenic bacteria. Interestingly, max2 mutant plants showed increased susceptibility to the bacterial necrotroph Pectobacterium carotovorum as well as to the hemi-biotroph Pseudomonas syringae but not to the fungal necrotroph Botrytis cinerea. max2 mutant phenotype was associated with constitutively increased stomatal conductance and decreased tolerance to apoplastic ROS but also with alterations in hormonal balance.

Conclusions: Our results suggest that MAX2 previously characterized for its role in regulation of polar auxin transport in Arabidopsis, and thus plant development also significantly influences plant disease resistance. We conclude that the increased susceptibility to P. syringae and P. carotovorum is due to increased stomatal conductance in max2 mutants promoting pathogen entry into the plant apoplast. Additional factors contributing to pathogen susceptibility in max2 plants include decreased tolerance to pathogen-triggered apoplastic ROS and alterations in hormonal signaling.

Show MeSH

Related in: MedlinePlus

Superoxide (O2•−) induced cell death inmax2mutants. Detached leaves from four week old soil grown wild-type Col-0, max2-1, max2-4 and rcd1-4 mutant plants were infiltrated with the O2•− generating system xanthine and xanthine oxidase (X/XO). Cell death was measured as relative ion leakage for 24 h. Data are means ± SE from 3 independent experiments with >20 leaves/line in each experiment. The result is presented as ratio of ion leakage of total ion concentration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4340836&req=5

Fig2: Superoxide (O2•−) induced cell death inmax2mutants. Detached leaves from four week old soil grown wild-type Col-0, max2-1, max2-4 and rcd1-4 mutant plants were infiltrated with the O2•− generating system xanthine and xanthine oxidase (X/XO). Cell death was measured as relative ion leakage for 24 h. Data are means ± SE from 3 independent experiments with >20 leaves/line in each experiment. The result is presented as ratio of ion leakage of total ion concentration.

Mentions: Interestingly, in accordance with the observed sensitivity to ozone (Figure 1), the accumulation of O2•− led to increased ion leakage in both max2 mutant lines in comparison to wild-type (Figure 2). In X/XO-infiltrated max2 mutant lines the ion leakage increased 25% during the first hour while in wild type the corresponding increase was 15% (Figure 2). Increase in ion leakage was even more distinct during the next 12 h. Since X/XO –experiment is done by infiltrating and thus, is independent of stomatal opening, it seems that MAX2 influences plant sensitivity to ROS in the level of mesophyll.Figure 2


The F-box protein MAX2 contributes to resistance to bacterial phytopathogens in Arabidopsis thaliana.

Piisilä M, Keceli MA, Brader G, Jakobson L, Jõesaar I, Sipari N, Kollist H, Palva ET, Kariola T - BMC Plant Biol. (2015)

Superoxide (O2•−) induced cell death inmax2mutants. Detached leaves from four week old soil grown wild-type Col-0, max2-1, max2-4 and rcd1-4 mutant plants were infiltrated with the O2•− generating system xanthine and xanthine oxidase (X/XO). Cell death was measured as relative ion leakage for 24 h. Data are means ± SE from 3 independent experiments with >20 leaves/line in each experiment. The result is presented as ratio of ion leakage of total ion concentration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4340836&req=5

Fig2: Superoxide (O2•−) induced cell death inmax2mutants. Detached leaves from four week old soil grown wild-type Col-0, max2-1, max2-4 and rcd1-4 mutant plants were infiltrated with the O2•− generating system xanthine and xanthine oxidase (X/XO). Cell death was measured as relative ion leakage for 24 h. Data are means ± SE from 3 independent experiments with >20 leaves/line in each experiment. The result is presented as ratio of ion leakage of total ion concentration.
Mentions: Interestingly, in accordance with the observed sensitivity to ozone (Figure 1), the accumulation of O2•− led to increased ion leakage in both max2 mutant lines in comparison to wild-type (Figure 2). In X/XO-infiltrated max2 mutant lines the ion leakage increased 25% during the first hour while in wild type the corresponding increase was 15% (Figure 2). Increase in ion leakage was even more distinct during the next 12 h. Since X/XO –experiment is done by infiltrating and thus, is independent of stomatal opening, it seems that MAX2 influences plant sensitivity to ROS in the level of mesophyll.Figure 2

Bottom Line: Interestingly, max2 mutant plants showed increased susceptibility to the bacterial necrotroph Pectobacterium carotovorum as well as to the hemi-biotroph Pseudomonas syringae but not to the fungal necrotroph Botrytis cinerea. max2 mutant phenotype was associated with constitutively increased stomatal conductance and decreased tolerance to apoplastic ROS but also with alterations in hormonal balance.We conclude that the increased susceptibility to P. syringae and P. carotovorum is due to increased stomatal conductance in max2 mutants promoting pathogen entry into the plant apoplast.Additional factors contributing to pathogen susceptibility in max2 plants include decreased tolerance to pathogen-triggered apoplastic ROS and alterations in hormonal signaling.

View Article: PubMed Central - PubMed

ABSTRACT

Background: The Arabidopsis thaliana F-box protein MORE AXILLARY GROWTH2 (MAX2) has previously been characterized for its role in plant development. MAX2 appears essential for the perception of the newly characterized phytohormone strigolactone, a negative regulator of polar auxin transport in Arabidopsis.

Results: A reverse genetic screen for F-box protein mutants altered in their stress responses identified MAX2 as a component of plant defense. Here we show that MAX2 contributes to plant resistance against pathogenic bacteria. Interestingly, max2 mutant plants showed increased susceptibility to the bacterial necrotroph Pectobacterium carotovorum as well as to the hemi-biotroph Pseudomonas syringae but not to the fungal necrotroph Botrytis cinerea. max2 mutant phenotype was associated with constitutively increased stomatal conductance and decreased tolerance to apoplastic ROS but also with alterations in hormonal balance.

Conclusions: Our results suggest that MAX2 previously characterized for its role in regulation of polar auxin transport in Arabidopsis, and thus plant development also significantly influences plant disease resistance. We conclude that the increased susceptibility to P. syringae and P. carotovorum is due to increased stomatal conductance in max2 mutants promoting pathogen entry into the plant apoplast. Additional factors contributing to pathogen susceptibility in max2 plants include decreased tolerance to pathogen-triggered apoplastic ROS and alterations in hormonal signaling.

Show MeSH
Related in: MedlinePlus