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Kung Y.-J.,Rockefeller University | Kung Y.-J.,National Chung Hsing University | Lin P.-C.,National Taiwan University | Yeh S.-D.,National Chung Hsing University | And 9 more authors.
Molecular Plant-Microbe Interactions | Year: 2014

Cross-protection triggered by a mild strain of virus acts as a prophylaxis to prevent subsequent infections by related viruses in plants; however, the underling mechanisms are not fully understood. Through mutagenesis, we isolated a mutant strain of Turnip mosaic virus (TuMV), named Tu- GK, that contains an Arg182Lys substitution in helper component-proteinase (HC-ProK) that confers complete cross-protection against infection by a severe strain of TuMV in Nicotiana benthamiana, Arabidopsis thaliana Col- 0, and the Arabidopsis dcl2-4/dcl4-1 double mutant defective in DICER-like ribonuclease (DCL)2/DCL4-mediated silencing. Our analyses showed that HC-ProK loses the ability to interfere with microRNA pathways, although it retains a partial capability for RNA silencing suppression triggered by DCL. We further showed that Tu-GK infection triggers strong salicylic acid (SA)-dependent and SAindependent innate immunity responses. Our data suggest that DCL2/4-dependent and -independent RNA silencing pathways are involved, and may crosstalk with basal innate immunity pathways, in host defense and in crossprotection. © 2014 The American Phytopathological Society. Source

Rostami H.,Islamic Azad University at Damghan | Haghnazari A.,University of Zanjan | Kavei G.,Iranian Materials and Energy Research Center | Ghareyazie B.,Agricultural Biotechnology Research Center | Hesari F.,Iranian Materials and Energy Research Center
Indian Journal of Biotechnology | Year: 2011

Different varieties of two plant species, Canola and Alfalfa were grown at exactly same laboratory conditions and bioreduction of Au (III) to Au (0) was studied. Subsequently, production of gold nano-particles of various morphologies and sizes were characterized. Plant seeds were grown in a culture medium that contained gold ions from KAuCl4. Gold nanoparticle formation was analyzed by atomic absorption spectrometry and transmission electron microscopy. Results showed that the plants pull up gold ions from KAuCl4 and form gold particles in nano sizes due to chemical behaviour of the gold. Significant differences in the nature of nano-particles were observed when particles synthesized by these two plant species were compared. The size range of gold nano-particles synthesized by Canola was 20-128 nm, while it was 8-48 nm by Alfalfa. Source

Ko C.-Y.,National Tsing Hua University | Ko C.-Y.,Agricultural Biotechnology Research Center | Lai Y.-L.,Academia Sinica, Taiwan | Liu W.-Y.,National Tsing Hua University | And 9 more authors.
Journal of Agricultural and Food Chemistry | Year: 2012

The Arabidopsis thaliana At1g68290 gene encoding an endonuclease was isolated and designated ENDO2, which was cloned into a binary vector to overexpress ENDO2 with a C-terminal 6 ×His-tag in A. thaliana. Our Arabidopsis transgenic lines harboring 35SP::ENDO2 produced stable active enzyme with high yield. The protein was affinity purified from transgenic plants, and its identity was confirmed by liquid chromatography-mass spectrometry and automatic Edman degradation. ENDO2 enzyme digests RNA, ssDNA, and dsDNA, with a substrate preference for ssDNA and RNA. The activity toward ssDNA (361.7 U/mg) is greater than its dsDNase activity (14.1 U/mg) at neutral pH. ENDO2 effectively cleaves mismatch regions in heteroduplex DNA containing single base pair mismatches or insertion/deletion bases and can be applied to high-throughput detection of single base mutation. Our data also validated that the removal of sugar groups from ENDO2 strongly affects its enzymatic stability and activity. © 2012 American Chemical Society. Source

Hsu F.-C.,Agricultural Biotechnology Research Center | Shih M.-C.,Agricultural Biotechnology Research Center
Plant signaling & behavior | Year: 2013

Since the first study of hypoxic response in plants with cDNA microarray in 2002, the number of hypoxia-responsive genes has grown to more than 2000. However, to date, only small numbers of hypoxia-responsive genes are known to confer hypoxic resistance. Most investigations in this area have focused on identifying which genes are responsive and then characterized how these genes are induced during hypoxia, but the roles of numerous genes in hypoxic response are still unknown. In our recent study, we demonstrated that a group of genes are induced by submergence to trigger plant immunity, which is a response to protect plants against a higher probability of pathogen infection during or after flooding. This work offered a brand new perspective, i.e., that hypoxia-responsive genes can be induced for reasons other than conferring hypoxic resistance. Possible reasons why these responses were triggered are discussed herein. Source

Chen Y.-Y.,Agricultural Biotechnology Research Center | Wang Y.,Academia Sinica, Taiwan | Shin L.-J.,Agricultural Biotechnology Research Center | Wu J.-F.,Academia Sinica, Taiwan | And 6 more authors.
Plant Physiology | Year: 2013

The homeostasis of iron (Fe) in plants is strictly regulated to maintain an optimal level for plant growth and development but not cause oxidative stress. About 30% of arable land is considered Fe deficient because of calcareous soil that renders Fe unavailable to plants. Under Fe-deficient conditions, Arabidopsis (Arabidopsis thaliana) shows retarded growth, disordered chloroplast development, and delayed flowering time. In this study, we explored the possible connection between Fe availability and the circadian clock in growth and development. Circadian period length in Arabidopsis was longer under Fe-deficient conditions, but the lengthened period was not regulated by the canonical Fe-deficiency signaling pathway involving nitric oxide. However, plants with impaired chloroplast function showed long circadian periods. Fe deficiency and impaired chloroplast function combined did not show additive effects on the circadian period, which suggests that plastid-to-nucleus retrograde signaling is involved in the lengthening of circadian period under Fe deficiency. Expression pattern analyses of the central oscillator genes in mutants defective in CIRCADIAN CLOCK ASSOCIATED1/LATE ELONGATED HYPOCOTYL or GIGANTEA demonstrated their requirement for Fe deficiency-induced long circadian period. In conclusion, Fe is involved in maintaining the period length of circadian rhythm, possibly by acting on specific central oscillators through a retrograde signaling pathway. © 2013 American Society of Plant Biologists. All Rights Reserved. Source

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