Virtually all plants are able to recognize attack by herbivorous insects and release volatile organic compounds (VOC) in response. Terpenes are the most abundant and varied class of insect-induced VOC from plants. Four genes encoding putative terpene synthases (MtTps1, MtTps2, MtTps3 and MtTps4) were shown to accumulate in Medicago truncatula Gaertn. in response to Spodoptera exigua (Hübner) feeding and methyl jasmonate treatment in a previous study [S.K. Gomez, M.M. Cox, J.C. Bede, K.K. Inoue, H.T. Alborn, J.H. Tumlinson, K.L. Korth, Lepidopteran herbivory and oral factors induce transcripts encoding novel terpene synthases in Medicago truncatula, Arch. Insect Biochem. Physiol. 58 (2005) 114-127.] The focus of the current study is the functional characterization of one (MtTps4) of these four genes. Using an M. truncatula cDNA clone, the insect-inducible putative terpene synthase was expressed in Escherichiacoli and shown to convert geranyl diphosphate (GPP) into the monoterpene (E)-beta-ocimene as the major product. The clone was therefore designated M. truncatula (E)-beta-ocimene synthase (MtEBOS). Transcripts encoding this enzyme accumulate in M. truncatula leaves in response to exogenous jasmonic acid treatments, lepidopteran herbivory, and lepidopteran oral secretions. Treatment with the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC) did not cause an increase in MtEBOS transcripts. The volatile (E)-beta-ocimene was released from leaves of both undamaged and insect-damaged plants, but at levels two-fold higher in insect-damaged M. truncatula. Although leaves have low constitutive levels of MtEBOS transcripts, RNA blot analysis indicates no constitutive expression in flowers, stems or roots. The strong insect-induced expression of this gene, and its correspondence with release of volatile ocimene, suggest that it plays an active role in indirect insect defenses in M. truncatula.
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http://dx.doi.org/10.1016/j.plaphy.2009.01.008 | DOI Listing |
Front Plant Sci
December 2024
Department of Genetics and Biochemistry, Clemson University, Clemson, SC, United States.
Two symbiotic processes, nodulation and arbuscular mycorrhiza, are primarily controlled by the plant's need for nitrogen (N) and phosphorus (P), respectively. Autoregulation of nodulation (AON) and autoregulation of mycorrhizal symbiosis (AOM) both negatively regulate their respective processes and share multiple components-plants that make too many nodules usually have higher arbuscular mycorrhiza (AM) fungal root colonization. The protein TML (TOO MUCH LOVE) was shown to function in roots to maintain susceptibly to rhizobial infection under low N conditions and control nodule number through AON in .
View Article and Find Full Text PDFBMC Plant Biol
December 2024
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China.
Background: Calcium-dependent protein kinases (CDPKs), play multiple roles in plant development, growth and response to bio- or abiotic stresses. Calmodulin-like domains typically contain four EF-hand motifs for Ca²⁺ binding. The CDPK gene family can be divided into four subgroups in Arabidopsis, and it has been identified in many plants, such as rice, tomato, but has not been investigated in alfalfa (Medicago sativa subsp.
View Article and Find Full Text PDFInt J Mol Sci
November 2024
Institute of Biology, University of Szczecin, Wąska 13, 71-415 Szczecin, Poland.
The phenylpropanoid biosynthesis pathway is involved in the response of plants to stress factors, including microorganisms. This paper presents how free-living strains of rhizobacteria KK5, KK7, KK4, and the symbiotic strain KK13 affect the expression of genes encoding phenylalanine ammonia-lyase (PAL), the activity of this enzyme, and the production of phenolic compounds in . Seedlings were inoculated with rhizobacteria, then at T0, T24, T72, and T168 after inoculation, the leaves and roots were analyzed for gene expression, enzyme activity, and the content of phenolic compounds.
View Article and Find Full Text PDFPlant Cell Rep
December 2024
Department of Biochemistry and Molecular Biology, Binzhou Medical University, Yantai, People's Republic of China.
All ten dehydrin genes from three Medicago species are responsive to different kinds of abiotic stress, and CAS31 confers transgenic plants salt tolerance by down-regulating HKT1 expression. Dehydrins are protective proteins playing crucial roles in the tolerance of plants to abiotic stresses. However, a full-scale and systemic analysis of total dehydrin genes in Medicago at the genome level is still lacking.
View Article and Find Full Text PDFNew Phytol
December 2024
National Key Lab of Agricultural Microbiology, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China.
Plant immunity is suppressed in the symbiotic nodule cells, thereby facilitating rhizobial infection. Medicago truncatula NODULES WITH ACTIVATED DEFENSE1 (MtNAD1) is crucial for suppressing immunity in nodules; however, its molecular function is unclear. We explored the molecular basis of the role of MtNAD1 in suppressing innate immunity in M.
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