A novel stress-inducible 12-oxophytodienoate reductase from Arabidopsis thaliana provides a potential link between Brassinosteroid-action and Jasmonic-acid synthesis

Wintersweet (Chimonanthus praecox L.) is an ornamental and economically significant shrub known for its unique flowering characteristics, especially the emission of abundant floral volatile organic compounds. Thus, an understanding of the molecular mechanism of the production of these compounds is necessary to create new breeds with high volatile production. In this study, two bHLH transcription factors (CpMYC2 and CpbHLH13) of Wintersweet H29 were functionally characterized to illustrate their possible role in the production of volatile compounds. The qRT-PCR results showed that the expression of CpMYC2 and CpbHLH13 increased from the flower budding to full bloom stage, indicating that these two genes may play an essential role in blooming and aroma production in wintersweet. Gas chromatography-mass spectroscopy (GC-MS) analysis revealed that the overexpression of CpMYC2 in arabidopsis (Arabidopsis thaliana) AtMYC2-2 mutant (Salk_083483) and tobacco (Nicotiana tabaccum) genotype Petit Havana SR1 significantly increased floral volatile monoterpene, especially linalool, while the overexpression of CpbHLH13 in Arabidopsis thaliana ecotype Columbia-0 (Col-0) and tobacco genotype SR1 increased floral sesquiterpene β-caryophyllene production in both types of transgenic plants respectively. High expression of terpene synthase (TPS) genes in transgenic A. thaliana along with high expression of CpMYC2 and CpbHLH13 in transgenic plants was also observed. The application of a combination of methyl jasmonic acid (MeJA) and gibberellic acid (GA3) showed an increment in linalool production in CpMYC2-overexpressing arabidopsis plants, and the high transcript level of TPS genes also suggested the involvement of CpMYC2 in the jasmonic acid (JA) signaling pathway. These results indicate that both the CpMYC2 and CpbHLH13 transcription factors of wintersweet are possibly involved in the positive regulation and biosynthesis of monoterpene (linalool) and sesquiterpene (β-caryophyllene) in transgenic plants. This study also indicates the potential application of wintersweet as a valuable genomic material for the genetic modification of floral scent in other flowering plants that produce less volatile compounds.

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Resistance of Arabidopsis thaliana to the obligate biotrophic parasite Plasmodiophora brassicae

Plant Protection Science ◽

10.17221/10543-pps ◽

2017 ◽

Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽

pp. 519-522 ◽

Cited By ~ 3

Author(s):

A. Arbeiter ◽

M. Fähling ◽

H. Graf ◽

M.D. Sacristán ◽

J. Siemens

Keyword(s):

Arabidopsis Thaliana ◽

Salicylic Acid ◽

Jasmonic Acid ◽

Resistance Gene ◽

Resistance Genes ◽

Plasmodiophora Brassicae ◽

Chromosome 1 ◽

Coding Sequences ◽

Resistance Phenotype ◽

Resistance Reaction

Two resistance phenotypes to P. brassicae have been found in A. thaliana. A first resistance phenotype has been detected to the isolate 'e<sub>2</sub>' and is polygenically inherited. The second resistance to isolate 'e<sub>3</sub>' is caused by the dominant resistance gene RPB1. By crossing no influence could be shown for salicylic acid, jasmonic acid and ethylene in the latter resistance reaction. The RPB1 locus was narrowed down to 71 kb on chromosome 1, where three pseudogenes and 13 coding sequences are located. Six of them showed cosegregation with RPB1. None of these sequences have similarities to identified resistance genes or other known genes. Ten coding sequences were expressed, but CDS9 was exclusively expressed in the resistant ecotype Tsu-0.

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