AM-Induced Alteration in the Expression of Genes, Encoding Phosphorus Transporters and Enzymes of Carbohydrate Metabolism in Medicago lupulina

Andrey Yurkov; Alexey Kryukov; Anastasia Gorbunova; Andrey Sherbakov; Ksenia Dobryakova; Yulia Mikhaylova; Alexey Afonin; Maria Shishova

doi:10.3390/plants9040486

AM-Induced Alteration in the Expression of Genes, Encoding Phosphorus Transporters and Enzymes of Carbohydrate Metabolism in Medicago lupulina

Plants (Basel). 2020 Apr 10;9(4):486. doi: 10.3390/plants9040486.

Authors

Andrey Yurkov¹, Alexey Kryukov¹, Anastasia Gorbunova^{1

2}, Andrey Sherbakov¹, Ksenia Dobryakova³, Yulia Mikhaylova⁴, Alexey Afonin⁵, Maria Shishova⁶

Affiliations

¹ Laboratory of Ecology of Symbiotic and Associative Rhizobacteria/All-Russia Research Institute for Agricultural Microbiology, 196608 Saint Petersburg, Russia.
² Department of Geobotany and Plant Ecology/Saint Petersburg State University, 199034 Saint Petersburg, Russia.
³ Laboratory of Molecular and Environmental Physiology/Komarov Botanical Institute of the Russian Academy of Sciences, 197376 Saint Petersburg, Russia.
⁴ Laboratory of Biosystematics and Cytology/Komarov Botanical Institute of the Russian Academy of Sciences, 197376 Saint Petersburg, Russia.
⁵ Laboratory of Genetics of Plant-Microbe Interactions/All-Russia Research Institute for Agricultural Microbiology, 196608 Saint Petersburg, Russia.
⁶ Department of Plant Physiology and Biochemistry/Saint Petersburg State University, 199034 Saint Petersburg, Russia.

Abstract

Plant-microbe interactions, including those of arbuscular mycorrhiza (AM), have been investigated for a wide spectrum of model plants. The present study focuses on an analysis of gene expression that encodes phosphate and sugar transporters and carbohydrate metabolic enzymes in a new model plant, the highly mycotrophic Medicago lupulina MLS-1 line under conditions of phosphorus deficiency and inoculation with Rhizophagus irregularis. Expression profiles were detected by RT-PCR at six plant stages of development (second leaf, third leaf, shooting, axillary shoot branching initiation, axillary shoot branching, flowering initiation). In comparison to control (without AM), the variant with AM inoculation exhibited a significant elevation of transcription levels of carbohydrate metabolic enzymes (MlSUS, MlHXK1) and sucrose transporters (MlSUC4) in M. lupulina leaves at the shooting stage. We suggest that this leads to a significant increase in the frequency of AM infection, an abundance of mycelium in roots and an increase in AM efficiency (which is calculated by the fresh weight of aerial parts and roots at the axillary shoot branching initiation stage). In roots, the specificity of MlPT4 and MlATP1 gene expressions were revealed for effective AM symbiosis. The level of MlPT4 transcripts in AM roots increased more than tenfold in comparison to that of non-specific MlPT1 and MlPT2. For the first time, MlPT1 expression was shown to increase sharply against MlPT2 in M. lupulina roots without AM at the shooting initiation stage. A significant increase in MlRUB expression was revealed at late stages in the host plant's development, during axillary shoot branching and flowering initiation. The opposite changes characterized MlHXK1 expression. Alteration in MlHXK1 gene transcription was the same, but was more pronounced in roots. The obtained results indicate the importance of genes that encode phosphate transporters and the enzymes of carbohydrate metabolism for effective AM development at the shooting stage in the host plant.

Keywords: Medicago lupulina; Rhizophagus irregularis; arbuscular mycorrhiza; efficient symbiosis; gene expression; phosphorus transporter; sugar metabolism.

Abstract

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