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A comparative study on Ca content and distribution in two Gesneriaceae species reveals distinctive mechanisms to cope with high rhizospheric soluble calcium.

Li W, Xu F, Chen S, Zhang Z, Zhao Y, Jin Y, Li M, Zhu Y, Liu Y, Yang Y, Deng X - Front Plant Sci (2014)

Bottom Line: Excessive Ca is toxic to plants thus significantly affects plant growth and species distribution in Ca-rich karst areas.By phenotype screening of transgenic plants expressing high Ca-inducible genes from B. hygrometrica, the expression of BhDNAJC2 in A. thaliana was found to enhance plant growth and photosynthesis under high soluble Ca stress.Taken together, our results revealed that distinctive mechanisms were employed in the two Gesneriaceae karst habitants to cope with a high Ca environment.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Plant Resources and Beijing Botanical Garden, Institute of Botany, The Chinese Academy of Sciences Beijing, China ; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences Beijing, China ; College of Life Sciences, University of Chinese Academy of Sciences Beijing, China.

ABSTRACT
Excessive Ca is toxic to plants thus significantly affects plant growth and species distribution in Ca-rich karst areas. To understand how plants survive high Ca soil, laboratory experiments were established to compare the physiological responses and internal Ca distribution in organ, tissue, cell, and intracellular levels under different Ca levels for Lysionotus pauciflorus and Boea hygrometrica, two karst habitant Gesneriaceae species in Southwest China. In the controlled condition, L. pauciflorus could survive as high as 200 mM rhizospheric soluble Ca, attributed to a series of physiological responses and preferential storage that limited Ca accumulation in chloroplasts of palisade cells. In contrast, B. hygrometrica could survive only 20 mM rhizospheric soluble Ca, but accumulated a high level of internal Ca in both palisade and spongy cells without disturbance on photosynthetic activity. By phenotype screening of transgenic plants expressing high Ca-inducible genes from B. hygrometrica, the expression of BhDNAJC2 in A. thaliana was found to enhance plant growth and photosynthesis under high soluble Ca stress. BhDNAJC2 encodes a recently reported heat shock protein (HSP) 40 family DnaJ-domain protein. The Ca-resistant phenotype of BhDNAJC2 highlights the important role of chaperone-mediated protein quality control in Ca tolerance in B. hygrometrica. Taken together, our results revealed that distinctive mechanisms were employed in the two Gesneriaceae karst habitants to cope with a high Ca environment.

No MeSH data available.


Related in: MedlinePlus

Ca accumulation and distribution in the vein and non-vein parts of L. pauciflorus leaves. (A) Vein. (B) Non-vein. Ca content was detected by SEM X-ray line profiles. Plants were treated with 2.5, 100, 200 mM Ca concentrations respectively for 7 days. Yellow line, the scanning line. Red curve, Ca intensity counts. Blue curve, Mg intensity counts. Y-axis, Ca intensity counts; X-axis, position on line scan (μm). Scale bar = 100 μm. ue, upper epidermis; pm, palisade mesophyll; cc, collenchyme; vb, vascular bundle; pc, parenchyma; ep, epithelial cells; sm, spongy mesophyll; le, lower epidermis.
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Figure 4: Ca accumulation and distribution in the vein and non-vein parts of L. pauciflorus leaves. (A) Vein. (B) Non-vein. Ca content was detected by SEM X-ray line profiles. Plants were treated with 2.5, 100, 200 mM Ca concentrations respectively for 7 days. Yellow line, the scanning line. Red curve, Ca intensity counts. Blue curve, Mg intensity counts. Y-axis, Ca intensity counts; X-axis, position on line scan (μm). Scale bar = 100 μm. ue, upper epidermis; pm, palisade mesophyll; cc, collenchyme; vb, vascular bundle; pc, parenchyma; ep, epithelial cells; sm, spongy mesophyll; le, lower epidermis.

Mentions: L. pauciflorus leaves contain an amphicribral vascular bundle in the midrib (Figure 4A), a thick upper epidermis structure that is composed of one layer of parenchyma and two or three layers of large epithelial cells, a typical mesophyll structure that is composed of several layers of compact thin and small palisade cells and incompact middle-sized round spongy cells, and a hairless thin layer of lower epidermis cells (Figure 4B). As shown by SEM X-ray line profiles, a valley of Ca signal was detected in the vascular bundle in midribs in plants under all treatments, indicating the effective unloading to mesophyll cells (Figure 4A). The Ca intensities in spongy cells were always 2–3 fold more than that in palisade cells and upper epidermis in non-vein sections of leaves in all treatments (Figure 4B), indicating the spongy cells were main Ca storage locations in leaves.


A comparative study on Ca content and distribution in two Gesneriaceae species reveals distinctive mechanisms to cope with high rhizospheric soluble calcium.

Li W, Xu F, Chen S, Zhang Z, Zhao Y, Jin Y, Li M, Zhu Y, Liu Y, Yang Y, Deng X - Front Plant Sci (2014)

Ca accumulation and distribution in the vein and non-vein parts of L. pauciflorus leaves. (A) Vein. (B) Non-vein. Ca content was detected by SEM X-ray line profiles. Plants were treated with 2.5, 100, 200 mM Ca concentrations respectively for 7 days. Yellow line, the scanning line. Red curve, Ca intensity counts. Blue curve, Mg intensity counts. Y-axis, Ca intensity counts; X-axis, position on line scan (μm). Scale bar = 100 μm. ue, upper epidermis; pm, palisade mesophyll; cc, collenchyme; vb, vascular bundle; pc, parenchyma; ep, epithelial cells; sm, spongy mesophyll; le, lower epidermis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4238373&req=5

Figure 4: Ca accumulation and distribution in the vein and non-vein parts of L. pauciflorus leaves. (A) Vein. (B) Non-vein. Ca content was detected by SEM X-ray line profiles. Plants were treated with 2.5, 100, 200 mM Ca concentrations respectively for 7 days. Yellow line, the scanning line. Red curve, Ca intensity counts. Blue curve, Mg intensity counts. Y-axis, Ca intensity counts; X-axis, position on line scan (μm). Scale bar = 100 μm. ue, upper epidermis; pm, palisade mesophyll; cc, collenchyme; vb, vascular bundle; pc, parenchyma; ep, epithelial cells; sm, spongy mesophyll; le, lower epidermis.
Mentions: L. pauciflorus leaves contain an amphicribral vascular bundle in the midrib (Figure 4A), a thick upper epidermis structure that is composed of one layer of parenchyma and two or three layers of large epithelial cells, a typical mesophyll structure that is composed of several layers of compact thin and small palisade cells and incompact middle-sized round spongy cells, and a hairless thin layer of lower epidermis cells (Figure 4B). As shown by SEM X-ray line profiles, a valley of Ca signal was detected in the vascular bundle in midribs in plants under all treatments, indicating the effective unloading to mesophyll cells (Figure 4A). The Ca intensities in spongy cells were always 2–3 fold more than that in palisade cells and upper epidermis in non-vein sections of leaves in all treatments (Figure 4B), indicating the spongy cells were main Ca storage locations in leaves.

Bottom Line: Excessive Ca is toxic to plants thus significantly affects plant growth and species distribution in Ca-rich karst areas.By phenotype screening of transgenic plants expressing high Ca-inducible genes from B. hygrometrica, the expression of BhDNAJC2 in A. thaliana was found to enhance plant growth and photosynthesis under high soluble Ca stress.Taken together, our results revealed that distinctive mechanisms were employed in the two Gesneriaceae karst habitants to cope with a high Ca environment.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Plant Resources and Beijing Botanical Garden, Institute of Botany, The Chinese Academy of Sciences Beijing, China ; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences Beijing, China ; College of Life Sciences, University of Chinese Academy of Sciences Beijing, China.

ABSTRACT
Excessive Ca is toxic to plants thus significantly affects plant growth and species distribution in Ca-rich karst areas. To understand how plants survive high Ca soil, laboratory experiments were established to compare the physiological responses and internal Ca distribution in organ, tissue, cell, and intracellular levels under different Ca levels for Lysionotus pauciflorus and Boea hygrometrica, two karst habitant Gesneriaceae species in Southwest China. In the controlled condition, L. pauciflorus could survive as high as 200 mM rhizospheric soluble Ca, attributed to a series of physiological responses and preferential storage that limited Ca accumulation in chloroplasts of palisade cells. In contrast, B. hygrometrica could survive only 20 mM rhizospheric soluble Ca, but accumulated a high level of internal Ca in both palisade and spongy cells without disturbance on photosynthetic activity. By phenotype screening of transgenic plants expressing high Ca-inducible genes from B. hygrometrica, the expression of BhDNAJC2 in A. thaliana was found to enhance plant growth and photosynthesis under high soluble Ca stress. BhDNAJC2 encodes a recently reported heat shock protein (HSP) 40 family DnaJ-domain protein. The Ca-resistant phenotype of BhDNAJC2 highlights the important role of chaperone-mediated protein quality control in Ca tolerance in B. hygrometrica. Taken together, our results revealed that distinctive mechanisms were employed in the two Gesneriaceae karst habitants to cope with a high Ca environment.

No MeSH data available.


Related in: MedlinePlus