In most oilseeds, two evolutionarily unrelated acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes, DGAT1 and DGAT2, are the main contributors to the acylation of diacylglycerols in the synthesis ...of triacylglycerol. DGAT1 and DGAT2 are both present in the important crop oilseed rape (
), with each type having four isoforms. We studied the activities of DGAT isoforms during seed development in microsomal fractions from two oilseed rape cultivars: edible, low-erucic acid (22:1) MONOLIT and nonedible high-erucic acid MAPLUS. Whereas the specific activities of DGATs were similar with most of the tested acyl-CoA substrates in both cultivars, MAPLUS had 6- to 14-fold higher activity with 22:1-CoA than did MONOLIT. Thus, DGAT isoforms with different acyl-CoA specificities are differentially active in the two cultivars. We characterized the acyl-CoA specificities of all DGAT isoforms in oilseed rape in the microsomal fractions of yeast cells heterologously expressing these enzymes. All four DGAT1 isoforms showed similar and broad acyl-CoA specificities. However, DGAT2 isoforms had much narrower acyl-CoA specificities: two DGAT2 isoforms were highly active with 22:1-CoA, while the ability of the other two isoforms to use this substrate was impaired. These findings elucidate the importance, which a DGAT isoform with suitable acyl-CoA specificity may have, when aiming for high content of a particular fatty acid in plant triacylglycerol reservoirs.
Phospholipase A(2) (PLA(2)) is a lipolytic enzyme that hydrolyses phospholipids in the cell membrane. In the present study, we investigated the role of secreted PLA(2) (VlsPLA(2)) in Verticillium ...longisporum, a fungal phytopathogen that mostly infects plants belonging to the Brassicaceae family, causing severe annual yield loss worldwide. Expression of the VlsPLA(2) gene, which encodes active PLA(2), is highly induced during the interaction of the fungus with the host plant Brassica napus. Heterologous expression of VlsPLA(2) in Nicotiana benthamiana resulted in increased synthesis of certain phospholipids compared to plants in which enzymatically inactive PLA(2) was expressed (VlsPLA(2)(Delta CD)). Moreover, VlsPLA(2) suppresses the hypersensitive response triggered by the Cf4/Avr4 complex, thereby suppressing the chitin--induced reactive oxygen species burst. VlsPLA(2)-overexpressing V. longisporum strains showed increased virulence in Arabidopsis plants, and transcriptomic analysis of this fungal strain revealed that the induction of the gene contributed to increased virulence. VlsPLA(2) was initially localized to the host nucleus and then translocated to the chloroplasts at later time points. In addition, VlsPLA(2) bound to the vesicle-associated membrane protein A (VAMPA) and was transported to the nuclear membrane. In the nucleus, VlsPLA(2) caused major alterations in the expression levels of genes encoding transcription factors and subtilisin-like proteases, which play a role in plant immunity. In conclusion, our study showed that VlsPLA(2) acts as a virulence factor, possibly by hydrolysing host nuclear envelope phospholipids, which, through a signal transduction cascade, may suppress basal plant immune responses.
Salinity is a global challenge to sustainable agriculture, impacting plant growth at cellular and functional levels. Nevertheless, silicon (Si), a multifunctional micro-element, plays a vital role in ...restoring and maintaining growth and development during unfavourable abiotic conditions such as high salinity exposure. Therefore, in the current research, two salinity levels S1; 1 M (1000 mM) NaCl and S2; 2 M (2000 mM) NaCl were used to assess the effects of exogenous Si (Si-1; 150 mg/L and Si-2; 250 mg/L) on key biological characteristics and especially the metabolite profiles of Panicum turgidum plants. Our findings revealed that the salt stress negatively affected the plants through high salt content (Na + and Cl − ) that further antagonized the essential nutrient balance in tissues; increased NH 4 + , but lowered NO 3 − and K + in both roots and leaves. The excessive production of NH 4 + led to over-accumulation of methylglyoxal (MG), resulting in the hyper-accumulation of sugars and altering the concentrations of amino acids, thereby inducing diabetes-like symptoms in P. turgidum plants. Interestingly, Si application restored the growth of P. turgidum plants by reducing oxidative damage thereby modifying the nutritional status, metabolic and biochemical characteristics of the plants. Specifically, the application of Si-2 showed improvement of key biological indictors in leaves and roots under both salinity levels. The current study also demonstrated that Si substantially reduced the NH 4 + -mediated MG-induced stress by lowering the concentration of MG, up-regulating the antioxidant capacity of various enzymes glyoxalase I (Gly-I), glyoxalase II (Gly-II), glutathione (GSH), glutamine: 2-oxoglutarate aminotransferase (GOGAT), nitrate reductase (NR), glutamine synthetase (GS), glutamate dehydrogenase (GDH); with concomitant changes in the levels of sugar/carbohydrates in roots and leaves of P. turgidum .
The world is on the verge of receiving new life forms that will profoundly and irrevocably change the global economy: the "gene hunters" who first cloned the gene in 1973 are now not only modifying ...existing species but also creating new plants and animals. Ready or not for such awesome power, the human race has put itself in a position to govern evolution. What will we do with the abilities we now command? asks this broad and stimulating book on the role of plant material in economic development. Writing in a style that is easily understandable even to those with no background in biotechnology, Calestous Juma begins by showing how the importation of plants strengthened the British Empire and brought the United States to global agricultural superiority. He goes on to explore the current international competition for genetic material and the potential impact of biotechnology on the relationship of the developed and developing world. Juma points out that biotechnology poses real dangers to the third world. Often one of the few exportable resources that a developing country possesses is an unusual or rare crop, but biotechnological techniques make possible the cultivation of many such crops outside their natural habitats, potentially eliminating the need to import the crops from the countries in which they grow indigenously. After discussing the threat of biotechnology, Juma comes full circle and points out that it does not have to be a threat. Actually, tremendous benefits could accrue to the third world from biotechnology--if and only if that new technology is adapted to its needs.
Originally published in 1989.
ThePrinceton Legacy Libraryuses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.
The agronomic application of nanotechnology in plants (phytonanotechnology) has the potential to alter conventional plant production systems, allowing for the controlled release of agrochemicals ...(e.g., fertilizers, pesticides, and herbicides) and target-specific delivery of biomolecules (e.g., nucleotides, proteins, and activators). An improved understanding of the interactions between nanoparticles (NPs) and plant responses, including their uptake, localization, and activity, could revolutionize crop production through increased disease resistance, nutrient utilization, and crop yield. Herewith, we review potential applications of phytonanotechnology and the key processes involved in the delivery of NPs to plants. To ensure both the safe use and social acceptance of phytonanotechnology, the adverse effects, including the risks associated with the transfer of NPs through the food chain, are discussed.
The field of nanotechnology has great potential within plant sciences and plant production systems.
The agronomic application of nanotechnology has thus far received comparatively little interest relative to the application within human systems.
We review the potential applications and future opportunities of nanotechnology in plant sciences, thereby assisting in bridging the divide between human and agricultural nanotechnology.
The application of nanotechnology in plant sciences will benefit from the development of improved analytical techniques that enable the in situ analysis of NPs in planta with a low detection limit and high lateral resolution.
Regardless of the benefits of nanotechnology for plant sciences, the principle of ‘safety-by-design’ must be heeded to address community concerns about the potential adverse effects of novel engineered nanoparticles (ENPs) on ecological systems.
Flavonoids are secondary metabolites that fulfil a multitude of functions during the plant life cycle. In Arabidopsis proanthocyanidins (PAs) are flavonoids that specifically accumulate in the ...innermost integuments of the seed testa (i.e. endothelium), as well as in the chalaza and micropyle areas, and play a vital role in protecting the embryo against various biotic and abiotic stresses. PAs accumulation in the endothelium requires the activity of the MADS box transcription factor TRANSPARENT TESTA (TT) 16 (ARABIDOPSIS B-SISTER/AGAMOUS-LIKE 32) and the UDP-glycosyltransferase TT15 (UGT80B1). Interestingly tt16 and tt15 mutants display a very similar flavonoid profiles and patterns of PA accumulation. By using a combination of genetic, molecular, biochemical, and histochemical methods, we showed that both TT16 and TT15 act upstream the PA biosynthetic pathway, but through two distinct genetic routes. We also demonstrated that the activity of TT16 in regulating cell fate determination and PA accumulation in the endothelium is required in the chalaza prior to the globular stage of embryo development. Finally this study provides new insight showing that TT16 and TT15 functions extend beyond PA biosynthesis in the inner integuments of the Arabidopsis seed coat.
The ability to synthesize Indole-3-acetic acid (IAA) is widely associated with the plant growth promoting rhizobacteria (PGPR). The present work deals with isolation and characterization of such ...bacteria from the rhizosphere of medicinal plant Stevia rebaudiana and optimization of IAA production from its isolates. The optimization of IAA production was carried out at different pH and temperature with varied carbon and nitrogen sources of culture media. Out of different isolates obtained, three of them were screened as efficient PGPRs on the basis of different plant growth promoting attributes. Isolates CA1001 and CA2004 showed better production of IAA at pH 9 (91.7 µg ml−1) and at temperature 37 °C (81.7 µg ml−1). Dextrose (1%) was found to be the best carbon source for isolate CA1001 with 104 µg ml−1 IAA production. Isolate CA 2004 showed best production of IAA 36 µg ml−1 and 34 µg ml−1 at 1.5% and 1% Beef extract as nitrogen source respectively. Isolate CA 1001 showed 32 µg ml−1 IAA production at 0.5% nicotinic acid concentration. From the current study, CA1001 and CA2004 emerged as noble alternatives for IAA production further which also resulted in root and shoot biomass generation in crop plants, hence can be further used as bio-inoculants for plant growth promotion.
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