Abstract
The integration of cell division in root growth and development requires mediation of developmental and physiological signals through regulation of cyclin-dependent kinase activity. Cells within the pericycle form de novo lateral root meristems, and D-type cyclins (CYCD), as regulators of the G₁-to-S phase cell cycle transition, are anticipated to play a role. Here, we show that the D-type cyclin protein CYCD2;1 is nuclear in Arabidopsis thaliana root cells, with the highest concentration in apical and lateral meristems. Loss of CYCD2;1 has a marginal effect on unstimulated lateral root density, but CYCD2;1 is rate-limiting for the response to low levels of exogenous auxin. However, while CYCD2;1 expression requires sucrose, it does not respond to auxin. The protein Inhibitor-Interactor of CDK/Kip Related Protein2 (ICK2/KRP2), which interacts with CYCD2;1, inhibits lateral root formation, and ick2/krp2 mutants show increased lateral root density. ICK2/KRP2 can modulate the nuclear levels of CYCD2;1, and since auxin reduces ICK2/KRP2 protein levels, it affects both activity and cellular distribution of CYCD2;1. Hence, as ICK2/KRP2 levels decrease, the increase in lateral root density depends on CYCD2;1, irrespective of ICK2/CYCD2;1 nuclear localization. We propose that ICK2/KRP2 restrains root ramification by maintaining CYCD2;1 inactive and that this modulates pericycle responses to auxin fluctuations.
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Claims 11
Claim · model-written summary
CYCD2;1 is nuclear in Arabidopsis root cells, with the highest concentration in apical and lateral meristems.
- Taxon
- Arabidopsis
Arabidopsist0 - Organ / stage
- apical and lateral meristemse1
- Gene
- CYCD2;1e1
- Outcome
- concentratione1
- Direction
- higheste1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e1“the D-type cyclin protein CYCD2;1 is nuclear in Arabidopsis thaliana root cells, with the highest concentration in apical and lateral meristems”
Claim · model-written summary
Loss of CYCD2;1 has a marginal effect on unstimulated lateral root density in Arabidopsis.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Loss of CYCD2;1e0
- Outcome
- unstimulated lateral root densitye0
- Direction
- marginal effecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e0“Loss of CYCD2;1 has a marginal effect on unstimulated lateral root density”
Claim · model-written summary
CYCD2;1 is rate-limiting for the Arabidopsis response to low levels of exogenous auxin.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- low levels of exogenous auxine2
- Gene
- CYCD2;1e2
- Outcome
- responsee2
- Direction
- rate-limitinge2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e2“CYCD2;1 is rate-limiting for the response to low levels of exogenous auxin”
Claim · model-written summary
CYCD2;1 expression requires sucrose in Arabidopsis.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e3“while CYCD2;1 expression requires sucrose, it does not respond to auxin”
Claim · model-written summary
CYCD2;1 expression in Arabidopsis does not respond to auxin.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- auxine3
- Gene
- CYCD2;1e3
- Outcome
- expressione3
- Direction
- does not responde3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e3“while CYCD2;1 expression requires sucrose, it does not respond to auxin”
Claim · model-written summary
ICK2/KRP2 inhibits lateral root formation in Arabidopsis.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- ICK2/KRP2e7
- Outcome
- lateral root formatione7
- Direction
- inhibitse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e7“The protein Inhibitor-Interactor of CDK/Kip Related Protein2 (ICK2/KRP2), which interacts with CYCD2;1, inhibits lateral root formation, and ick2/krp2 mutants show increased lateral root density”
Claim · model-written summary
ick2/krp2 mutants of Arabidopsis show increased lateral root density.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ick2/krp2 mutantse7
- Outcome
- lateral root densitye7
- Direction
- increasede7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e7“The protein Inhibitor-Interactor of CDK/Kip Related Protein2 (ICK2/KRP2), which interacts with CYCD2;1, inhibits lateral root formation, and ick2/krp2 mutants show increased lateral root density”
Claim · model-written summary
ICK2/KRP2 can modulate the nuclear levels of CYCD2;1 in Arabidopsis.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- ICK2/KRP2e4
- Outcome
- nuclear levels of CYCD2;1e4
- Direction
- modulatee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e4“ICK2/KRP2 can modulate the nuclear levels of CYCD2;1, and since auxin reduces ICK2/KRP2 protein levels”
Claim · model-written summary
Auxin reduces ICK2/KRP2 protein levels in Arabidopsis.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- auxine4
- Gene
- ICK2/KRP2e4
- Outcome
- protein levelse4
- Direction
- reducese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e4“ICK2/KRP2 can modulate the nuclear levels of CYCD2;1, and since auxin reduces ICK2/KRP2 protein levels”
Claim · model-written summary
As ICK2/KRP2 levels decrease, the increase in Arabidopsis lateral root density depends on CYCD2;1.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- ICK2/KRP2 levels decreasee5
- Gene
- CYCD2;1e5
- Outcome
- lateral root densitye5
- Direction
- increasee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e5“as ICK2/KRP2 levels decrease, the increase in lateral root density depends on CYCD2;1”
Claim · model-written summary
ICK2/KRP2 probably restrains root ramification by maintaining CYCD2;1 inactive.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- ICK2/KRP2e6
- Outcome
- root ramificatione6
- Qualifier
- maintaining CYCD2;1 inactivee6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The Arabidopsis D-Type Cyclin CYCD2;1”
e6“ICK2/KRP2 restrains root ramification by maintaining CYCD2;1 inactive”