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Root-to-shoot Cd translocation via the xylem is the major process determining shoot and grain cadmium accumulation in rice.

Uraguchi S, Mori S, Kuramata M, Kawasaki A, Arao T, Ishikawa S - J. Exp. Bot. (2009)

Bottom Line: Time-dependence and concentration-dependence of symplastic Cd absorption in roots were revealed not to be responsible for the different Cd accumulation between the two cultivars because root Cd uptake was not greater in the Cd-accumulating cultivar 'Habataki' compared with 'Sasanishiki'.The results showed strong correlation between Cd levels in xylem sap and shoots and grains among the 69 rice accessions.Overall, the results presented in this study revealed that the root-to-shoot Cd translocation via the xylem is the major and common physiological process determining the Cd accumulation level in shoots and grains of rice plants.

View Article: PubMed Central - PubMed

Affiliation: Soil Environment Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki, 305-8604, Japan.

ABSTRACT
Physiological properties involved in divergent cadmium (Cd) accumulation among rice genotypes were characterized using the indica cultivar 'Habataki' (high Cd in grains) and the japonica cultivar 'Sasanishiki' (low Cd in grains). Time-dependence and concentration-dependence of symplastic Cd absorption in roots were revealed not to be responsible for the different Cd accumulation between the two cultivars because root Cd uptake was not greater in the Cd-accumulating cultivar 'Habataki' compared with 'Sasanishiki'. On the other hand, rapid and greater root-to-shoot Cd translocation was observed in 'Habataki', which could be mediated by higher abilities in xylem loading of Cd and transpiration rate as a driving force. To verify whether different abilities in xylem-mediated shoot-to-root translocation generally account for the genotypic variation in shoot Cd accumulation in rice, the world rice core collection, consisting of 69 accessions which covers the genetic diversity of almost 32,000 accessions of cultivated rice, was used. The results showed strong correlation between Cd levels in xylem sap and shoots and grains among the 69 rice accessions. Overall, the results presented in this study revealed that the root-to-shoot Cd translocation via the xylem is the major and common physiological process determining the Cd accumulation level in shoots and grains of rice plants.

Show MeSH
Time-dependent Cd accumulation in shoots of a low-Cd-accumulating japonica cultivar ‘Sasanishiki’ and a high-Cd-accumulating indica cultivar ‘Habataki’. 14-d-old seedlings were exposed to a nutrient solution containing 0.18 μM CdSO4 for 14 d. (A) Cd concentration in shoots. (B) Accumulated Cd amount in shoots. (C) Shoot:root ratio of accumulated Cd amount. Data are presented as means with SD (n=3).
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fig2: Time-dependent Cd accumulation in shoots of a low-Cd-accumulating japonica cultivar ‘Sasanishiki’ and a high-Cd-accumulating indica cultivar ‘Habataki’. 14-d-old seedlings were exposed to a nutrient solution containing 0.18 μM CdSO4 for 14 d. (A) Cd concentration in shoots. (B) Accumulated Cd amount in shoots. (C) Shoot:root ratio of accumulated Cd amount. Data are presented as means with SD (n=3).

Mentions: Cadmium concentration in the shoots increased according to the duration of the Cd treatment in both cultivars, and the concentration was 1.2–24-fold greater in ‘Habataki’ than in ‘Sasanishiki’ during the 14 d Cd treatment (Fig. 2A). The total amount of Cd accumulated in the shoots of ‘Habataki’ showed 1.8–34-times higher values than that of ‘Sasanishiki’ (Fig. 2B). It is noteworthy that a considerable accumulation of Cd was observed, even after only 1 h exposure in ‘Habataki’ (Fig. 2A, B). The shoot:root Cd ratio of ‘Habataki’ was 1.3–8.5-times higher than that of ‘Sasanishiki’ throughout the Cd treatment, except for 7 d after Cd exposure (Fig. 2C). These results demonstrate a more rapid and greater Cd translocation into the shoots of the Cd-accumulating cultivar ‘Habataki’ than into those of ‘Sasanishiki’.


Root-to-shoot Cd translocation via the xylem is the major process determining shoot and grain cadmium accumulation in rice.

Uraguchi S, Mori S, Kuramata M, Kawasaki A, Arao T, Ishikawa S - J. Exp. Bot. (2009)

Time-dependent Cd accumulation in shoots of a low-Cd-accumulating japonica cultivar ‘Sasanishiki’ and a high-Cd-accumulating indica cultivar ‘Habataki’. 14-d-old seedlings were exposed to a nutrient solution containing 0.18 μM CdSO4 for 14 d. (A) Cd concentration in shoots. (B) Accumulated Cd amount in shoots. (C) Shoot:root ratio of accumulated Cd amount. Data are presented as means with SD (n=3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2692013&req=5

fig2: Time-dependent Cd accumulation in shoots of a low-Cd-accumulating japonica cultivar ‘Sasanishiki’ and a high-Cd-accumulating indica cultivar ‘Habataki’. 14-d-old seedlings were exposed to a nutrient solution containing 0.18 μM CdSO4 for 14 d. (A) Cd concentration in shoots. (B) Accumulated Cd amount in shoots. (C) Shoot:root ratio of accumulated Cd amount. Data are presented as means with SD (n=3).
Mentions: Cadmium concentration in the shoots increased according to the duration of the Cd treatment in both cultivars, and the concentration was 1.2–24-fold greater in ‘Habataki’ than in ‘Sasanishiki’ during the 14 d Cd treatment (Fig. 2A). The total amount of Cd accumulated in the shoots of ‘Habataki’ showed 1.8–34-times higher values than that of ‘Sasanishiki’ (Fig. 2B). It is noteworthy that a considerable accumulation of Cd was observed, even after only 1 h exposure in ‘Habataki’ (Fig. 2A, B). The shoot:root Cd ratio of ‘Habataki’ was 1.3–8.5-times higher than that of ‘Sasanishiki’ throughout the Cd treatment, except for 7 d after Cd exposure (Fig. 2C). These results demonstrate a more rapid and greater Cd translocation into the shoots of the Cd-accumulating cultivar ‘Habataki’ than into those of ‘Sasanishiki’.

Bottom Line: Time-dependence and concentration-dependence of symplastic Cd absorption in roots were revealed not to be responsible for the different Cd accumulation between the two cultivars because root Cd uptake was not greater in the Cd-accumulating cultivar 'Habataki' compared with 'Sasanishiki'.The results showed strong correlation between Cd levels in xylem sap and shoots and grains among the 69 rice accessions.Overall, the results presented in this study revealed that the root-to-shoot Cd translocation via the xylem is the major and common physiological process determining the Cd accumulation level in shoots and grains of rice plants.

View Article: PubMed Central - PubMed

Affiliation: Soil Environment Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki, 305-8604, Japan.

ABSTRACT
Physiological properties involved in divergent cadmium (Cd) accumulation among rice genotypes were characterized using the indica cultivar 'Habataki' (high Cd in grains) and the japonica cultivar 'Sasanishiki' (low Cd in grains). Time-dependence and concentration-dependence of symplastic Cd absorption in roots were revealed not to be responsible for the different Cd accumulation between the two cultivars because root Cd uptake was not greater in the Cd-accumulating cultivar 'Habataki' compared with 'Sasanishiki'. On the other hand, rapid and greater root-to-shoot Cd translocation was observed in 'Habataki', which could be mediated by higher abilities in xylem loading of Cd and transpiration rate as a driving force. To verify whether different abilities in xylem-mediated shoot-to-root translocation generally account for the genotypic variation in shoot Cd accumulation in rice, the world rice core collection, consisting of 69 accessions which covers the genetic diversity of almost 32,000 accessions of cultivated rice, was used. The results showed strong correlation between Cd levels in xylem sap and shoots and grains among the 69 rice accessions. Overall, the results presented in this study revealed that the root-to-shoot Cd translocation via the xylem is the major and common physiological process determining the Cd accumulation level in shoots and grains of rice plants.

Show MeSH