Plant lipidomics

Welti, R. 2011. Plant Lipidomics. AOCS Lipid Library, from http //lipidlibrary.aocs. org/plantbio/plantlipidomics/index.htm. accessed April 2011. 

The developers concluded that LipidBlast could be successfully applied to analyze MS/MS data from over 40 different mass spectrometer types and used with other available search engines and scoring algorithms, which represents a paradigm shift in lipidomics because it is not feasible to chemically synthesize all metabolites or natural products as authentic standards for library generation or quantification purposes. Moreover, the current array of MS/MS mass spectra for plant, animal, viral, and bacterial lipids in LipidBlast could be readily extended to many other important lipid classes. 

This method is modified for lipid extraction for lipidomic analysis. For example, Welti et al. omitted the filtering step and directly extracted the lipids from plant tissues by Folch extraction method [45]. 

Welti, R., Shah, J., Li, W., Li, M., Chen, J., Burke, J.J., Fauconnier, M.L., Chapman, K., Chye, M.L. and Wang, X. (2007) Plant lipidomics Discerning biological function by profiling plant complex lipids using mass spectrometry. Front. Biosci. 12, 2494-2506. 

The networks of GPL biosynthesis pathways present in animals and plants are different from those of yeast or bacteria and thus they are separately illustrated (Figure 16.1). The gene(s) and protein(s) involved in each biosynthesis pathway can be found in review articles (e.g., [7]). It is important to recognize the cell type of a study prior to interpreting lipidomics data. 

Lipidomics profiling was used to determine the effects of plant sterols on lipid metabolism [142] since it is well known that plant sterol intervention could lead to reduction of both total cholesterol and LDL cholesterol in human [143]. In the study, two plant sterol-enriched yogurt drinks containing different fat content were given to healthy mildly hypercholesterolemic subjects for 4 weeks and then lipidomic analysis of serum samples were performed [142]. It was found that both drinks resulted in reduction of both total and LDL cholesterol levels [144]. In addition, the low-fat drink resulted in a reduction of the levels of several SM species. This reduction, which correlates well with the reduction of LDL cholesterol, could be due to the co-localization of SM and cholesterol on the surface layer of LDL lipoproteins. 

As the development of lipidomics field, mass spectrometric analysis of plant lipids has been advanced accordingly. The branch of lipidomics in analysis of plant cellular lipids utilizing mass spectrometry was specifically called plant lipidomics [1], As described early in the book (Chapter 3), all kinds of MS-based lipidomics approaches, particularly those based on ESl-MS or ESI-MS/MS, could be used in plant lipidomics. The advantages of ESl-MS-based methods over traditional lipid analytical approaches for analysis of plant lipids were extensively discussed [1-3]. 

As described in Chapter 15, correction for different stable isotopologue distribution due to differences in the number of carbon atoms between the species of interest and the selected internal standard(s) and correction for baseline should be performed prior to the comparison of the intensities. It should be recognized that in the majority of the studies in plant lipidomics after direct infusion, MDMS-type analysis is generally not conducted thus, the isobaric or isomeric species are not resolved as regrettable. A detailed protocol for profihng of polar hpids in plants after direct infusion can be found [9]. 

In this chapter, a few lipid classes relatively specific to plant lipidomes in comparison to those of mammalian cellular lipidomes are first described. As described in Chapter 6, only the fragmentation patterns of individual lipid classes are summarized. Then, examples of the application of plant lipidomics for plant research are briefly given. 

Analysis of Cer, hydroxy Cer, and GluCer by ESI-MS and ESI-MS/MS is described in details in Chapter 7. But the analysis of IPC and GIPC, which is special to plant lipidomics relative to animal lipids, is discussed below. 

The fragmentation patterns resulted from other IPC ions in the positive- or negative-ion mode are also very informative, all of which can be found in the study performed by Hsu and colleagues [23]. However, these fragmentation patterns may not be practically useful for profiling IPC species present in plant lipidomes. 

LIPIDOMICS FOR PLANT BIOLOGY 18.3.1 Stress-Induced Changes of Plant Lipidomes... 

Plant membrane lipids undergo many changes when the plants are exposed to various stress conditions such as cold, heat, mechanical wounding, and phosphorus deficiency. Lipidomics allows researchers to reveal the lipid changes induced by the... 

In another study, the changes of lipidomes in response to temperature were conducted as a temperature-dependent manner (i.e., at 4, 21, and 32 °C) by LC-MS [13]. In addition to the previous findings as described earlier, it was also found that an immediate decrease in unsaturated species of PG was present in plants under high-temperature conditions (i.e., 32 °C). This finding suggests that the reduction of unsaturation in PG species could be the first stages of adaptation to heat stress conditions. 

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