Effects of root morphology and leaf transpiration on Cd uptake and translocation in rice under warming

Liqiang Ge1,2, Long Cang1*, Jie Yang1,2, Dongmei Zhou1*

1 Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China

2 University of Chinese Academy of Sciences, Beijing 100049, China

Liqiang Ge

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Long Cang(corresponding author)

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Jie Yang

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Dongmei Zhou (corresponding author)

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Text S1 Methods for chlorophyll extraction and relative permeability measurement

Chlorophyll was extracted using homogenization of 0.1 g fresh leaf with 8 ml 80% acetone in a mortar (adjusted to pH 7.8 with sodium phosphate buffer) and then centrifuged at 5000 g for 10 min. Chlorophyll a, b, and total chlorophyll were calculated according to the equation of Porra et al. (1989).

The relative permeability was calculated as described by Zwiazek and Blake (1991). 2.5g fresh root was kept in 50-cc vials containing 25 ml of deionized water in two sets. One set was kept at 25 °C for 15 min and the other set at 100 °C in boiling water bath for 15 min, the respective electrical conductivities C1 and C2 were measured using a conductivity meter. The relative permeability was the ratio of C1 to C2 with percentage.

References

Porra, R., Thompson, W., Kriedemann, P., 1989. Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents: verification of the concentration of chlorophyll standards by atomic absorption spectroscopy. Biochimica et Biophysica Acta (BBA)-Bioenergetics 975, 384-394.

Zwiazek, J.J., Blake, T.J., 1991. Early detection of membrane injury in black spruce (Picea mariana). Canadian journal of forest research 21, 401-404.

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Table S1Total chlorophyll content in leaves and relative permeability of roots for rice seedlings with different treatments (CK, Cd, and Cd+ATS) under the control (CT), asymmetric (AW) and symmetric warming (SW) in Test One

Index / Treatment / CT / AW / SW
Total chlorophyll
in leaves
(mg kg-1) / CK / 1.92 b / 2.10 a / 1.99 ab
Cd / 1.52 b / 1.86 ab / 1.98 a
Cd+ATS / 1.80 b / 1.92 ab / 2.06 a
Relative
permeability
of roots (%) / CK / 2.63 a / 2.68 a / 3.81 a
Cd / 2.70 b / 3.78 a / 3.45 a
Cd+ATS / 3.00 b / 3.28 ab / 3.68 a

Note: CK, Cd, and Cd+ATS denote treatments without Cd, Cd exposure, and Cd exposure with antitranspirant, respectively. Mean values followed by different lowercase letters in each index of different tissues are significantly different (p < 0.05, n = 4).

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Fig. S1Roots classification based on root diameter for Cd exposure treatment for 16 d under CT, AW, and SW in Test One

Note: yellow roots (diameter ≤ 0.2 mm), red roots (0.2 < diameter ≤ 0.5 mm), green roots (diameter > 0.5 mm), and blue roots (overlapped roots) were classified using WinRhizo software in left figures. The corresponding figures in right side were the pictures of local roots for the according treatments.

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Fig.S2 Total root surface area for treatment without Cd exposure after pre-culturing for 16 d under CT, AW, and SW

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