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Cytokinin-dependent secondary growth determines root biomass in radish (Raphanus sativus L.).

Jang G, Lee JH, Rastogi K, Park S, Oh SH, Lee JY - J. Exp. Bot. (2015)

Bottom Line: Through a comparative analysis with Arabidopsis root expression data, we identified putative cambium-enriched transcription factors in radish and analysed their expression in representative inbred lines featuring distinctive radial growth.We found that cell proliferation activities in the cambium positively correlated with radial growth and final yields of radish roots.Expression analysis of candidate transcription factor genes revealed that some genes are differentially expressed between inbred lines and that the difference is due to the distinct cytokinin response.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, College of Natural Science, Seoul National University, Seoul 151-747, Korea.

No MeSH data available.


Related in: MedlinePlus

Dynamic changes in the cambial activity of radish roots. (A) Immunolocalization of PCNA in radish roots. PCNA expression was analysed in 7-week-old roots of lines 212 and 214 by immunolocalization assays, with (+) and () indicate PCNA antibody-treated and untreated conditions, respectively. (B) Developmental stage-dependent regulation of cambial activity. The cambial activity of the indicated inbred lines was analysed by immunolocalization of PCNA over time. c, Cortex; p, parenchyma; arrowhead, cambium. Bars, 200 μm.
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Figure 5: Dynamic changes in the cambial activity of radish roots. (A) Immunolocalization of PCNA in radish roots. PCNA expression was analysed in 7-week-old roots of lines 212 and 214 by immunolocalization assays, with (+) and () indicate PCNA antibody-treated and untreated conditions, respectively. (B) Developmental stage-dependent regulation of cambial activity. The cambial activity of the indicated inbred lines was analysed by immunolocalization of PCNA over time. c, Cortex; p, parenchyma; arrowhead, cambium. Bars, 200 μm.

Mentions: To understand the relationships between dynamic changes in the cambial zone and cell division activity we performed immunolocalization assays in the cambial zones using an antibody against PCNA. PCNA is an evolutionarily conserved protein that is required for DNA replication. Its expression is highly upregulated in actively dividing cells (Dimova et al., 2003; Shimizu and Mori, 1998a, b). Our test experiment using 7-week-old root sections of lines 212 and 214 with or without treatment with PCNA antibody confirmed that the dividing cell-specific fluorescence signals came only from antibody-treated sections (Fig. 5A). High expression of PCNA in root cambium was also confirmed in actively growing scarlet globe radish roots (Supplementary Fig. S6, available at JXB online). We then carried out immunolocalization analyses using the roots of lines 212, 214, 216, and 218 collected at five different developmental stages (Fig. 5B). Line 214 and 216 plants showed a high level of PCNA in the cambium zone between 5 and 7 weeks, and then a very low level at 8 and 9 weeks. Line 212 plants did not show PCNA expression in 5-week-old roots but showed increasing PCNA levels in the cambium zone of 6-week-old roots. PCNA expression reached its highest level in 7-week-old root and then disappeared abruptly in line 212. In contrast to lines 212, 214, and 216, PCNA expression was always below the detection level in line 218. This indicated that the cambial cell division activity of line 218 plants was very low compared with the other inbred lines. Such developmental stage-dependent changes in cambial cell division together with dynamic changes in cambium size and cell organization in inbred lines suggest that cell division activities in the cambium play a critical role in the radial growth of radish roots.


Cytokinin-dependent secondary growth determines root biomass in radish (Raphanus sativus L.).

Jang G, Lee JH, Rastogi K, Park S, Oh SH, Lee JY - J. Exp. Bot. (2015)

Dynamic changes in the cambial activity of radish roots. (A) Immunolocalization of PCNA in radish roots. PCNA expression was analysed in 7-week-old roots of lines 212 and 214 by immunolocalization assays, with (+) and () indicate PCNA antibody-treated and untreated conditions, respectively. (B) Developmental stage-dependent regulation of cambial activity. The cambial activity of the indicated inbred lines was analysed by immunolocalization of PCNA over time. c, Cortex; p, parenchyma; arrowhead, cambium. Bars, 200 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4507762&req=5

Figure 5: Dynamic changes in the cambial activity of radish roots. (A) Immunolocalization of PCNA in radish roots. PCNA expression was analysed in 7-week-old roots of lines 212 and 214 by immunolocalization assays, with (+) and () indicate PCNA antibody-treated and untreated conditions, respectively. (B) Developmental stage-dependent regulation of cambial activity. The cambial activity of the indicated inbred lines was analysed by immunolocalization of PCNA over time. c, Cortex; p, parenchyma; arrowhead, cambium. Bars, 200 μm.
Mentions: To understand the relationships between dynamic changes in the cambial zone and cell division activity we performed immunolocalization assays in the cambial zones using an antibody against PCNA. PCNA is an evolutionarily conserved protein that is required for DNA replication. Its expression is highly upregulated in actively dividing cells (Dimova et al., 2003; Shimizu and Mori, 1998a, b). Our test experiment using 7-week-old root sections of lines 212 and 214 with or without treatment with PCNA antibody confirmed that the dividing cell-specific fluorescence signals came only from antibody-treated sections (Fig. 5A). High expression of PCNA in root cambium was also confirmed in actively growing scarlet globe radish roots (Supplementary Fig. S6, available at JXB online). We then carried out immunolocalization analyses using the roots of lines 212, 214, 216, and 218 collected at five different developmental stages (Fig. 5B). Line 214 and 216 plants showed a high level of PCNA in the cambium zone between 5 and 7 weeks, and then a very low level at 8 and 9 weeks. Line 212 plants did not show PCNA expression in 5-week-old roots but showed increasing PCNA levels in the cambium zone of 6-week-old roots. PCNA expression reached its highest level in 7-week-old root and then disappeared abruptly in line 212. In contrast to lines 212, 214, and 216, PCNA expression was always below the detection level in line 218. This indicated that the cambial cell division activity of line 218 plants was very low compared with the other inbred lines. Such developmental stage-dependent changes in cambial cell division together with dynamic changes in cambium size and cell organization in inbred lines suggest that cell division activities in the cambium play a critical role in the radial growth of radish roots.

Bottom Line: Through a comparative analysis with Arabidopsis root expression data, we identified putative cambium-enriched transcription factors in radish and analysed their expression in representative inbred lines featuring distinctive radial growth.We found that cell proliferation activities in the cambium positively correlated with radial growth and final yields of radish roots.Expression analysis of candidate transcription factor genes revealed that some genes are differentially expressed between inbred lines and that the difference is due to the distinct cytokinin response.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, College of Natural Science, Seoul National University, Seoul 151-747, Korea.

No MeSH data available.


Related in: MedlinePlus