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Global analysis of gene expression profiles in physic nut (Jatropha curcas L.) seedlings exposed to drought stress.

Zhang C, Zhang L, Zhang S, Zhu S, Wu P, Chen Y, Li M, Jiang H, Wu G - BMC Plant Biol. (2015)

Bottom Line: The genes found to be up-regulated in roots were related to abscisic acid (ABA) synthesis and ABA signal transduction, and to the synthesis of raffinose.Genes related to unsaturated fatty acid biosynthesis were down-regulated and polyunsaturated fatty acids were significantly reduced in leaves 7 days after withholding irrigation.As drought stress increased, genes related to ethylene synthesis, ethylene signal transduction and chlorophyll degradation were up-regulated, and the chlorophyll content of leaves was significantly reduced by 7 days after withholding irrigation.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. ahzc2009@163.com.

ABSTRACT

Background: Physic nut (Jatropha curcas L.) is a small perennial tree or large shrub, which is well-adapted to semi-arid regions and is considered to have potential as a crop for biofuel production. It is now regarded as an excellent model for studying biofuel plants. However, our knowledge about the molecular responses of this species to drought stress is currently limited.

Results: In this study, genome-wide transcriptional profiles of roots and leaves of 8-week old physic nut seedlings were analyzed 1, 4 and 7 days after withholding irrigation. We observed a total of 1533 and 2900 differentially expressed genes (DEGs) in roots and leaves, respectively. Gene Ontology analysis showed that the biological processes enriched in droughted plants relative to unstressed plants were related to biosynthesis, transport, nucleobase-containing compounds, and cellular protein modification. The genes found to be up-regulated in roots were related to abscisic acid (ABA) synthesis and ABA signal transduction, and to the synthesis of raffinose. Genes related to ABA signal transduction, and to trehalose and raffinose synthesis, were up-regulated in leaves. Endoplasmic reticulum (ER) stress response genes were significantly up-regulated in leaves under drought stress, while a number of genes related to wax biosynthesis were also up-regulated in leaves. Genes related to unsaturated fatty acid biosynthesis were down-regulated and polyunsaturated fatty acids were significantly reduced in leaves 7 days after withholding irrigation. As drought stress increased, genes related to ethylene synthesis, ethylene signal transduction and chlorophyll degradation were up-regulated, and the chlorophyll content of leaves was significantly reduced by 7 days after withholding irrigation.

Conclusions: This study provides us with new insights to increase our understanding of the response mechanisms deployed by physic nut seedlings under drought stress. The genes and pathways identified in this study also provide much information of potential value for germplasm improvement and breeding for drought resistance.

No MeSH data available.


Chlorophyll, proline, raffinose and trehalose contents and fatty acid composition of leaves 7 days after withholding irrigation. A. Chlorophyll and proline contents of leaves 7 days after withholding irrigation; B. Raffinose and trehalose contents of leaves and roots 7 days after withholding irrigation determined by high performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD); C. Major fatty acids (mol %) in leaves 7 days after withholding irrigation, detected by gas chromatography. Values represent mean of n = 3 ± SD (Duncan test: *, P < 0.05; **, P < 0.01). CK, control; DR, drought treatment; FAT, fatty acyl-ACP thioesterase; SAD, stearoyl-ACP desaturase; FAD, fatty acid desaturase; C16:0, palmitate; C16:2, hexadecadienoic acid; C16:3, hexadecatrienoic acid; C18:0, stearate; C18:1, oleate; C18:2, linoleic acid; C18:3, α-linolenic acid; C21:0, heneicosanoate; C20:3, homogamma linolenate.
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Fig4: Chlorophyll, proline, raffinose and trehalose contents and fatty acid composition of leaves 7 days after withholding irrigation. A. Chlorophyll and proline contents of leaves 7 days after withholding irrigation; B. Raffinose and trehalose contents of leaves and roots 7 days after withholding irrigation determined by high performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD); C. Major fatty acids (mol %) in leaves 7 days after withholding irrigation, detected by gas chromatography. Values represent mean of n = 3 ± SD (Duncan test: *, P < 0.05; **, P < 0.01). CK, control; DR, drought treatment; FAT, fatty acyl-ACP thioesterase; SAD, stearoyl-ACP desaturase; FAD, fatty acid desaturase; C16:0, palmitate; C16:2, hexadecadienoic acid; C16:3, hexadecatrienoic acid; C18:0, stearate; C18:1, oleate; C18:2, linoleic acid; C18:3, α-linolenic acid; C21:0, heneicosanoate; C20:3, homogamma linolenate.

Mentions: Osmotic adjustment is crucial in plant resistance to drought stress and it contributes to water uptake and maintenance, membrane protection and ROS scavenging [64]. The genes related to osmotic adjustment that were up-regulated under drought stress in physic nut roots were mainly related to galactose and raffinose biosynthesis; they included JC_C100019062 (encoding galactinol synthase), JC_C100015469 and JC_C100008342 (encoding raffinose synthases) (Additional file 5: Table S5). Quantitative determination of oligosaccharides showed that the accumulation of raffinose was significantly increased in drought treated roots compared to control roots at 7 DAWI (Figure 4B).These data indicate that raffinose was important in conferring osmotic adjustment in the roots of physic nut seedlings under drought stress.Figure 4


Global analysis of gene expression profiles in physic nut (Jatropha curcas L.) seedlings exposed to drought stress.

Zhang C, Zhang L, Zhang S, Zhu S, Wu P, Chen Y, Li M, Jiang H, Wu G - BMC Plant Biol. (2015)

Chlorophyll, proline, raffinose and trehalose contents and fatty acid composition of leaves 7 days after withholding irrigation. A. Chlorophyll and proline contents of leaves 7 days after withholding irrigation; B. Raffinose and trehalose contents of leaves and roots 7 days after withholding irrigation determined by high performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD); C. Major fatty acids (mol %) in leaves 7 days after withholding irrigation, detected by gas chromatography. Values represent mean of n = 3 ± SD (Duncan test: *, P < 0.05; **, P < 0.01). CK, control; DR, drought treatment; FAT, fatty acyl-ACP thioesterase; SAD, stearoyl-ACP desaturase; FAD, fatty acid desaturase; C16:0, palmitate; C16:2, hexadecadienoic acid; C16:3, hexadecatrienoic acid; C18:0, stearate; C18:1, oleate; C18:2, linoleic acid; C18:3, α-linolenic acid; C21:0, heneicosanoate; C20:3, homogamma linolenate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4307156&req=5

Fig4: Chlorophyll, proline, raffinose and trehalose contents and fatty acid composition of leaves 7 days after withholding irrigation. A. Chlorophyll and proline contents of leaves 7 days after withholding irrigation; B. Raffinose and trehalose contents of leaves and roots 7 days after withholding irrigation determined by high performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD); C. Major fatty acids (mol %) in leaves 7 days after withholding irrigation, detected by gas chromatography. Values represent mean of n = 3 ± SD (Duncan test: *, P < 0.05; **, P < 0.01). CK, control; DR, drought treatment; FAT, fatty acyl-ACP thioesterase; SAD, stearoyl-ACP desaturase; FAD, fatty acid desaturase; C16:0, palmitate; C16:2, hexadecadienoic acid; C16:3, hexadecatrienoic acid; C18:0, stearate; C18:1, oleate; C18:2, linoleic acid; C18:3, α-linolenic acid; C21:0, heneicosanoate; C20:3, homogamma linolenate.
Mentions: Osmotic adjustment is crucial in plant resistance to drought stress and it contributes to water uptake and maintenance, membrane protection and ROS scavenging [64]. The genes related to osmotic adjustment that were up-regulated under drought stress in physic nut roots were mainly related to galactose and raffinose biosynthesis; they included JC_C100019062 (encoding galactinol synthase), JC_C100015469 and JC_C100008342 (encoding raffinose synthases) (Additional file 5: Table S5). Quantitative determination of oligosaccharides showed that the accumulation of raffinose was significantly increased in drought treated roots compared to control roots at 7 DAWI (Figure 4B).These data indicate that raffinose was important in conferring osmotic adjustment in the roots of physic nut seedlings under drought stress.Figure 4

Bottom Line: The genes found to be up-regulated in roots were related to abscisic acid (ABA) synthesis and ABA signal transduction, and to the synthesis of raffinose.Genes related to unsaturated fatty acid biosynthesis were down-regulated and polyunsaturated fatty acids were significantly reduced in leaves 7 days after withholding irrigation.As drought stress increased, genes related to ethylene synthesis, ethylene signal transduction and chlorophyll degradation were up-regulated, and the chlorophyll content of leaves was significantly reduced by 7 days after withholding irrigation.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. ahzc2009@163.com.

ABSTRACT

Background: Physic nut (Jatropha curcas L.) is a small perennial tree or large shrub, which is well-adapted to semi-arid regions and is considered to have potential as a crop for biofuel production. It is now regarded as an excellent model for studying biofuel plants. However, our knowledge about the molecular responses of this species to drought stress is currently limited.

Results: In this study, genome-wide transcriptional profiles of roots and leaves of 8-week old physic nut seedlings were analyzed 1, 4 and 7 days after withholding irrigation. We observed a total of 1533 and 2900 differentially expressed genes (DEGs) in roots and leaves, respectively. Gene Ontology analysis showed that the biological processes enriched in droughted plants relative to unstressed plants were related to biosynthesis, transport, nucleobase-containing compounds, and cellular protein modification. The genes found to be up-regulated in roots were related to abscisic acid (ABA) synthesis and ABA signal transduction, and to the synthesis of raffinose. Genes related to ABA signal transduction, and to trehalose and raffinose synthesis, were up-regulated in leaves. Endoplasmic reticulum (ER) stress response genes were significantly up-regulated in leaves under drought stress, while a number of genes related to wax biosynthesis were also up-regulated in leaves. Genes related to unsaturated fatty acid biosynthesis were down-regulated and polyunsaturated fatty acids were significantly reduced in leaves 7 days after withholding irrigation. As drought stress increased, genes related to ethylene synthesis, ethylene signal transduction and chlorophyll degradation were up-regulated, and the chlorophyll content of leaves was significantly reduced by 7 days after withholding irrigation.

Conclusions: This study provides us with new insights to increase our understanding of the response mechanisms deployed by physic nut seedlings under drought stress. The genes and pathways identified in this study also provide much information of potential value for germplasm improvement and breeding for drought resistance.

No MeSH data available.