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Wayne L.L.,Washington State University | Wayne L.L.,Dow AgroSciences | Wallis J.G.,Washington State University | Kumar R.,Washington State University | And 3 more authors.
Plant Cell | Year: 2013

In all eukaryotes, NADH:cytochrome b5 reductase provides electrons, via cytochrome b5, for a range of biochemical reactions in cellular metabolism, including for fatty acid desaturation in the endoplasmic reticulum. Studies in mammals, yeast, and in vitro plant systems have shown that cytochrome b5 can, at least in some circumstances, also accept electrons from NADPH:cytochrome P450 reductase, potentially allowing for redundancy in reductase function. Here, we report characterization of three T-DNA insertional mutants of the gene encoding cytochrome b5 reductase in Arabidopsis thaliana, CBR1. The progeny of plants heterozygous for the cbr1-2 allele segregated 6% homozygous mutants, while cbr1-3 and cbr1-4 heterozygotes segregated 1:1 heterozygous:wild type, indicating a gametophyte defect. Homozygous cbr1-2 seeds were deformed and required Suc for successful germination and seedling establishment. Vegetative growth of cbr1-2 plants was relatively normal, and they produced abundant flowers, but very few seeds. The pollen produced in cbr1-2 anthers was viable, but when germinated on cbr1-2 or wild-type stigmas, most of the resulting pollen tubes did not extend into the transmitting tract, resulting in a very low frequency of fertilization. These results indicate that cytochrome b5 reductase is not essential during vegetative growth but is required for correct pollen function and seed maturation. © American Society of Plant Biologists. All rights reserved.

Shamurailatpam A.,North - Eastern Hill University | Madhavan L.,National Bureau of Plant Genetic Resources | Yadav S.R.,Shivaji University | Bhat K.V.,National Research Center on Fingerprinting | Rao S.R.,North - Eastern Hill University
Nucleus (India) | Year: 2012

Wild species of Vigna are known to exhibit great range of phenotypic and genotypic diversity leading to development of several varieties and cultivars. However information regarding their chromosome biology is by and large lacking. The present study deals with karyotypic analysis in 10 taxa belonging to the genus Vigna. The details of chromosome morphology, karyotype formulae and symmetry index have been investigated. Heteromorphic chromosome pairs observed in two species viz. V. aconitifolia and V. radiata var. setulosa and NOR are also being reported in two taxa viz. V. mungo var. silvestris and V. sublobata. The karyomorphological studies confirmed that the asymmetry index of different taxa presently investigated had shown significant variation. The influence of karyotypic variation on genome evolution has been discussed in detail. © 2012 Archana Sharma Foundation of Calcutta.

Kumar R.,University of Missouri | Kumar R.,National Research Center on Fingerprinting | Tran L.-S.P.,University of Missouri | Tran L.-S.P.,RIKEN | And 3 more authors.
PLoS ONE | Year: 2012

Background: Synthesis of polyunsaturated fatty acids (PUFAs) in the endoplasmic reticulum of plants typically involves the fatty acid desaturases FAD2 and FAD3, which use cytochrome b 5 (Cb5) as an electron donor. Higher plants are reported to have multiple isoforms of Cb5, in contrast to a single Cb5 in mammals and yeast. Despite the wealth of information available on the roles of FAD2 and FAD3 in PUFA synthesis, information regarding the contributions of various Cb5 isoforms in desaturase-mediated reactions is limited. Results: The present functional characterization of Cb5 polypeptides revealed that all Arabidopsis Cb5 isoforms are not similarly efficient in ω-6 desaturation, as evidenced by significant variation in their product outcomes in yeast-based functional assays. On the other hand, characterization of Cb5 polypeptides of soybean (Glycine max) suggested that similar ω-6 desaturation efficiencies were shared by various isoforms. With regard to ω-3 desaturation, certain Cb5 genes of both Arabidopsis and soybean were shown to facilitate the accumulation of more desaturation products than others when co-expressed with their native FAD3. Additionally, similar trends of differential desaturation product accumulation were also observed with most Cb5 genes of both soybean and Arabidopsis even if co-expressed with non-native FAD3. Conclusions: The present study reports the first description of the differential nature of the Cb5 genes of higher plants in fatty acid desaturation and further suggests that ω-3/ω-6 desaturation product outcome is determined by the nature of both the Cb5 isoform and the fatty acid desaturases. © 2012 Kumar et al.

Das A.,North Bengal Agricultural University | Das A.,ICAR Research Complex for NEH Region | Das S.,Tea Research Association | Mondal T.K.,North Bengal Agricultural University | Mondal T.K.,National Research Center on Fingerprinting
Plant Molecular Biology Reporter | Year: 2012

Drought is an important abiotic stress that limits the production of tea in different regions of the world. Young roots of tea are responsible for nutrient and water uptake; hence, they are the first tissues to perceive drought stress. In this study, a forward suppression subtractive hybridization library was constructed from the tender roots of drought-tolerant tea (Camellia sinensis (L.) O. Kuntze) cultivar (TV-23) subjected to 21 days of drought stress. A total of 572 quality expressed sequence tags were generated by sequencing of 1,052 random clones which have resulted to 246 unigenes comprising 54 contigs and 192 singlets. The unigenes were assigned to various functional categories, i. e. cellular components, biological processes and molecular functions as defined for the Arabidopsis proteome. There were 13. 04% of differentially regulated genes that have been associated to various stresses. A total of 123 putative drought-responsive genes were identified which include candidate genes of ubiquitin-proteasome, glutathione metabolism and sugar metabolism pathways and several transcription factors. In order to determine the possible expression, 10 genes associated to drought-responsive pathways were further analysed by reverse transcription polymerase chain reaction. This study provides a basis for studying the drought tolerance mechanism of this important commercial crop which will also be a valuable resource for the functional genomics study of woody plants in future. © 2012 Springer-Verlag.

Mondal N.,National Research Center on Fingerprinting | Bhat K.V.,National Research Center on Fingerprinting | Srivastava P.S.,Jamia Hamdard University
JAOCS, Journal of the American Oil Chemists' Society | Year: 2010

A germplasm collection of 33 entries comprising 22 sesame (Sesamum indicum L.) cultivars, 4 landraces of S. mulayanum and 7 other accessions of 4 wild species were analyzed for the fatty acid compositions of their seed oil. The entries varied widely in their fatty acid compositions. The percentage content of oleic, linoleic, palmitic and erucic acids ranged between 36.7-52.4, 30.4-51.6, 9.1-14.8 and 0.0-8.0, respectively. Linolenic and arachidonic acids were the minor constituents but varied widely in wild species. Oleic and linoleic were the major fatty acids with mean values of 45.9 and 40.5%, respectively and the mean of their combined values was 86.4%. The polyunsaturated fatty acid (PUFA) compositions ranged from 30.9 to 52.5% showing high variation in PUFA in the germplasm. Linoleic acid content was very high in one landrace (47.8) and one accession each of three wild species, S. mulayanum (49.3), S. malabaricum (48.2) and S. radiatum (51.6%). Use of fatty acid ratios to estimate the efficiency of biosynthetic pathways resulted in high oleic and low linoleic desaturation ratios and consequently high linoleic and very low linolenic acid contents in seed oil. The results of this study provided useful background information on the germplasm and also identified a few accessions having high linoleic acid which can be used for developing cultivars with desirable fatty acid compositions. © 2010 AOCS.

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