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Characterization of transcriptome remodeling during cambium formation identifies MOL1 and RUL1 as opposing regulators of secondary growth.

Agusti J, Lichtenberger R, Schwarz M, Nehlin L, Greb T - PLoS Genet. (2011)

Bottom Line: Here, we describe the roles of two receptor-like kinases, REDUCED IN LATERAL GROWTH1 (RUL1) and MORE LATERAL GROWTH1 (MOL1), as opposing regulators of cambium activity.Their identification was facilitated by a novel in vitro system in which cambium formation is induced in isolated Arabidopsis stem fragments.By combining this system with laser capture microdissection, we characterized transcriptome remodeling in a tissue- and stage-specific manner and identified series of genes induced during different phases of cambium formation.

View Article: PubMed Central - PubMed

Affiliation: Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria.

ABSTRACT
Cell-to-cell communication is crucial for the development of multicellular organisms, especially during the generation of new tissues and organs. Secondary growth--the lateral expansion of plant growth axes--is a highly dynamic process that depends on the activity of the cambium. The cambium is a stem cell-like tissue whose activity is responsible for wood production and, thus, for the establishment of extended shoot and root systems. Attempts to study cambium regulation at the molecular level have been hampered by the limitations of performing genetic analyses in trees and by the difficulty of accessing this tissue in model systems such as Arabidopsis thaliana. Here, we describe the roles of two receptor-like kinases, REDUCED IN LATERAL GROWTH1 (RUL1) and MORE LATERAL GROWTH1 (MOL1), as opposing regulators of cambium activity. Their identification was facilitated by a novel in vitro system in which cambium formation is induced in isolated Arabidopsis stem fragments. By combining this system with laser capture microdissection, we characterized transcriptome remodeling in a tissue- and stage-specific manner and identified series of genes induced during different phases of cambium formation. In summary, we provide a means for investigating cambium regulation in unprecedented depth and present two signaling components that control a process responsible for the accumulation of a large proportion of terrestrial biomass.

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Marker analysis during CIS–incubation and sampling strategy.(A–E) The activity of the DR5rev:GFP reporter in CIS incubated stems (A–D) without NAA after 2 (A) or 5 days (B), and with apically applied NAA after 2 (C) or 5 days (D) in comparison to a fragment taken from the base of the inflorescence stem of an 18 cm tall plant (E). (F and G) APL:GUS detection in mock-treated (F) and NAA-treated (G) samples after 5 days of CIS-incubation. Signals in interfascicular regions are indicated by arrows. (H) Sampling strategy by LCM as also indicated in Figure 1A. Size bars in (A,F): 100 µm, same magnification in (A–E) and (F–G). The positions of primary vascular bundles are labeled by asterisks.
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pgen-1001312-g002: Marker analysis during CIS–incubation and sampling strategy.(A–E) The activity of the DR5rev:GFP reporter in CIS incubated stems (A–D) without NAA after 2 (A) or 5 days (B), and with apically applied NAA after 2 (C) or 5 days (D) in comparison to a fragment taken from the base of the inflorescence stem of an 18 cm tall plant (E). (F and G) APL:GUS detection in mock-treated (F) and NAA-treated (G) samples after 5 days of CIS-incubation. Signals in interfascicular regions are indicated by arrows. (H) Sampling strategy by LCM as also indicated in Figure 1A. Size bars in (A,F): 100 µm, same magnification in (A–E) and (F–G). The positions of primary vascular bundles are labeled by asterisks.

Mentions: (A and B) Comparison of cross-sections from a primary (A) and secondary (B) stem (IC: arrows in B). Blue: xylem/xylem fibers; red: fascicular and interfascicular cambium; yellow: phloem/phloem parenchyma; green: starch sheath. Triangle: see Figure 2H. (C) Origin of stem fragments for CIS-incubation. At the stage of collection, IC initiation was restricted to the region labeled in red [4]. (D) Experimental setup of CIS. (E–G) Stem fragments incubated without (E) and with (F) apically applied NAA in comparison to a stem immediately above the uppermost rosette leaf of a 15 cm tall plant (G). Arrows indicate dividing tissues in interfascicular regions. (H and I). Fragments incubated with basally applied NAA (H) and with apically applied NAA together with ubiquitously applied NPA (I, 1 µg/ml). Size bar in (E): 100 µm, same magnification in (E–I). The positions of primary vascular bundles are labeled by asterisks.


Characterization of transcriptome remodeling during cambium formation identifies MOL1 and RUL1 as opposing regulators of secondary growth.

Agusti J, Lichtenberger R, Schwarz M, Nehlin L, Greb T - PLoS Genet. (2011)

Marker analysis during CIS–incubation and sampling strategy.(A–E) The activity of the DR5rev:GFP reporter in CIS incubated stems (A–D) without NAA after 2 (A) or 5 days (B), and with apically applied NAA after 2 (C) or 5 days (D) in comparison to a fragment taken from the base of the inflorescence stem of an 18 cm tall plant (E). (F and G) APL:GUS detection in mock-treated (F) and NAA-treated (G) samples after 5 days of CIS-incubation. Signals in interfascicular regions are indicated by arrows. (H) Sampling strategy by LCM as also indicated in Figure 1A. Size bars in (A,F): 100 µm, same magnification in (A–E) and (F–G). The positions of primary vascular bundles are labeled by asterisks.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3040665&req=5

pgen-1001312-g002: Marker analysis during CIS–incubation and sampling strategy.(A–E) The activity of the DR5rev:GFP reporter in CIS incubated stems (A–D) without NAA after 2 (A) or 5 days (B), and with apically applied NAA after 2 (C) or 5 days (D) in comparison to a fragment taken from the base of the inflorescence stem of an 18 cm tall plant (E). (F and G) APL:GUS detection in mock-treated (F) and NAA-treated (G) samples after 5 days of CIS-incubation. Signals in interfascicular regions are indicated by arrows. (H) Sampling strategy by LCM as also indicated in Figure 1A. Size bars in (A,F): 100 µm, same magnification in (A–E) and (F–G). The positions of primary vascular bundles are labeled by asterisks.
Mentions: (A and B) Comparison of cross-sections from a primary (A) and secondary (B) stem (IC: arrows in B). Blue: xylem/xylem fibers; red: fascicular and interfascicular cambium; yellow: phloem/phloem parenchyma; green: starch sheath. Triangle: see Figure 2H. (C) Origin of stem fragments for CIS-incubation. At the stage of collection, IC initiation was restricted to the region labeled in red [4]. (D) Experimental setup of CIS. (E–G) Stem fragments incubated without (E) and with (F) apically applied NAA in comparison to a stem immediately above the uppermost rosette leaf of a 15 cm tall plant (G). Arrows indicate dividing tissues in interfascicular regions. (H and I). Fragments incubated with basally applied NAA (H) and with apically applied NAA together with ubiquitously applied NPA (I, 1 µg/ml). Size bar in (E): 100 µm, same magnification in (E–I). The positions of primary vascular bundles are labeled by asterisks.

Bottom Line: Here, we describe the roles of two receptor-like kinases, REDUCED IN LATERAL GROWTH1 (RUL1) and MORE LATERAL GROWTH1 (MOL1), as opposing regulators of cambium activity.Their identification was facilitated by a novel in vitro system in which cambium formation is induced in isolated Arabidopsis stem fragments.By combining this system with laser capture microdissection, we characterized transcriptome remodeling in a tissue- and stage-specific manner and identified series of genes induced during different phases of cambium formation.

View Article: PubMed Central - PubMed

Affiliation: Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria.

ABSTRACT
Cell-to-cell communication is crucial for the development of multicellular organisms, especially during the generation of new tissues and organs. Secondary growth--the lateral expansion of plant growth axes--is a highly dynamic process that depends on the activity of the cambium. The cambium is a stem cell-like tissue whose activity is responsible for wood production and, thus, for the establishment of extended shoot and root systems. Attempts to study cambium regulation at the molecular level have been hampered by the limitations of performing genetic analyses in trees and by the difficulty of accessing this tissue in model systems such as Arabidopsis thaliana. Here, we describe the roles of two receptor-like kinases, REDUCED IN LATERAL GROWTH1 (RUL1) and MORE LATERAL GROWTH1 (MOL1), as opposing regulators of cambium activity. Their identification was facilitated by a novel in vitro system in which cambium formation is induced in isolated Arabidopsis stem fragments. By combining this system with laser capture microdissection, we characterized transcriptome remodeling in a tissue- and stage-specific manner and identified series of genes induced during different phases of cambium formation. In summary, we provide a means for investigating cambium regulation in unprecedented depth and present two signaling components that control a process responsible for the accumulation of a large proportion of terrestrial biomass.

Show MeSH
Related in: MedlinePlus