Publicação
Identification and real time PCR expression analysis of drought-related lipid metabolism genes in soybean
| Resumo: | Soybean (Glycine max) is among the most important food crops due to the high protein and lipid content of its seeds. Its importance in the world economy is not only related to its use as a food commodity but also due to its impact in the biodiesel industry. World agriculture face major constrains with the increase of global warming, being drought a major factor affecting productivity. Soybean is considerably sensitive to drought. Previous studies have shown that the lipid content and composition of plant leaves change in response to water deficit, as a result of variations in both biosynthetic and lipolytic enzymatic activities. These changes can be related to the induction of signaling pathways, leading to the activation of drought resistance mechanisms, but can also reflect structural changes at the membrane level. Several lipolytic enzymes are involved in such processes, including phospholipases A (PLA), which remove fatty acids from membrane lipids. Despite the importance of this group of enzymes in the mediation of stress responses, revealed namely by studies using Arabidopsis, little is known about their role in drought-induced remodeling of the lipid metabolism in soybean leaves. In the present study, a comprehensive analysis of the PLA superfamily in the soybean genome allowed the identification of 50 genes, belonging to the three major plant PLA families: patatin-like phospholipases (pPLA), DAD-like phospholipase A1 (PLA1) and low molecular weight secreted phospholipase A2 (sPLA2) as well as a phosphatidic acid-preferring PLA1 (PA-preferring PLA1). Although the number of soybean PLAs is considerably higher than the one present in Arabidopsis, comparative sequence analyses revealed a high conservation between orthologs from the two species, which may indicate conserved functions. The expression of a subset of PLA genes, selected according to publicly available transcriptomics data and predicted subcellular location, together with other key lipid metabolism genes, was investigated by qPCR, under three stages of water deficit. Lipid profiling data revealed that the typical reduction in the plastidial lipids content was accompanied by a transient increase in linolenic-acid enriched- phosphatidylcholine and neutral lipids, suggesting a channeling of plastidial fatty acids into triacylglycerol. The potential involvement of PLA isoforms in this process is discussed, taking into account their expression profiles under water deficit, together with literature data on the subcellular locations and substrate specificities of orthologous proteins. Since thylakoid membranes are affected by drought, some photosynthetic features were assessed, such as chlorophyll- content and fluorescence, through pulse amplitude modulation (PAM) and laser induced fluorescence (LIF) analyses. The results show variations in chlorophyll content as well as an adaptation of the photosynthetic apparatus to moderate drought, but reveal the negative impact of severe drought. |
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| Autores principais: | Ferreira, Daniela Alves Jardim Sardinha |
| Assunto: | Soybean Phospholipase A superfamily Water deficit Gene expression Lipids profiling Teses de mestrado - 2017 |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Soybean (Glycine max) is among the most important food crops due to the high protein and lipid content of its seeds. Its importance in the world economy is not only related to its use as a food commodity but also due to its impact in the biodiesel industry. World agriculture face major constrains with the increase of global warming, being drought a major factor affecting productivity. Soybean is considerably sensitive to drought. Previous studies have shown that the lipid content and composition of plant leaves change in response to water deficit, as a result of variations in both biosynthetic and lipolytic enzymatic activities. These changes can be related to the induction of signaling pathways, leading to the activation of drought resistance mechanisms, but can also reflect structural changes at the membrane level. Several lipolytic enzymes are involved in such processes, including phospholipases A (PLA), which remove fatty acids from membrane lipids. Despite the importance of this group of enzymes in the mediation of stress responses, revealed namely by studies using Arabidopsis, little is known about their role in drought-induced remodeling of the lipid metabolism in soybean leaves. In the present study, a comprehensive analysis of the PLA superfamily in the soybean genome allowed the identification of 50 genes, belonging to the three major plant PLA families: patatin-like phospholipases (pPLA), DAD-like phospholipase A1 (PLA1) and low molecular weight secreted phospholipase A2 (sPLA2) as well as a phosphatidic acid-preferring PLA1 (PA-preferring PLA1). Although the number of soybean PLAs is considerably higher than the one present in Arabidopsis, comparative sequence analyses revealed a high conservation between orthologs from the two species, which may indicate conserved functions. The expression of a subset of PLA genes, selected according to publicly available transcriptomics data and predicted subcellular location, together with other key lipid metabolism genes, was investigated by qPCR, under three stages of water deficit. Lipid profiling data revealed that the typical reduction in the plastidial lipids content was accompanied by a transient increase in linolenic-acid enriched- phosphatidylcholine and neutral lipids, suggesting a channeling of plastidial fatty acids into triacylglycerol. The potential involvement of PLA isoforms in this process is discussed, taking into account their expression profiles under water deficit, together with literature data on the subcellular locations and substrate specificities of orthologous proteins. Since thylakoid membranes are affected by drought, some photosynthetic features were assessed, such as chlorophyll- content and fluorescence, through pulse amplitude modulation (PAM) and laser induced fluorescence (LIF) analyses. The results show variations in chlorophyll content as well as an adaptation of the photosynthetic apparatus to moderate drought, but reveal the negative impact of severe drought. |
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