A snapshot of the transcriptome ofMedicago truncatula(Fabales: Fabaceae) shoots and roots in response to an arbuscular mycorrhizal fungus and the pea aphid (Acyrthosiphon pisum) (Hemiptera: Aphididae)

Abstract

Plants simultaneously interact with belowground symbionts such as arbuscular mycorrhizal (AM) fungi and aboveground antagonists such as aphids. Generally, plants gain access to valuable resources including nutrients and water through the AM symbiosis and are more resistant to pests. Nevertheless, aphids’ performance improves on mycorrhizal plants, and it remains unclear whether a more nutritious food source and/or attenuated defenses are the contributing factors. This study examined the shoot and root transcriptome of barrel medic (Medicago truncatula Gaertn.) plants highly colonized by the AM fungus Rhizophagus irregularis (Blaszk., Wubet, Renker, and Buscot) C. Walker and A. Schüßler (Glomerales: Glomeraceae) and exposed to 7 days of mixed age pea aphid (Acyrthosiphon pisum (Harris)) herbivory. The RNA-seq samples chosen for this study showed that aphids were heavier when fed mycorrhizal plants compared to nonmycorrhizal plants. We hypothesized that (i) insect-related plant defense pathways will be downregulated in shoots of mycorrhizal plants with aphids compared to nonmycorrhizal plants with aphids; (ii) pathways involved in nutrient acquisition, carbohydrate-related and amino acid transport will be upregulated in shoots of mycorrhizal plants with aphids compared to nonmycorrhizal plants with aphids; and (iii) roots of mycorrhizal plants with aphids will exhibit mycorrhiza-induced resistance. The transcriptome data revealed that the gene repertoire related to defenses, nutrient transport, and carbohydrates differs between nonmycorrhizal and mycorrhizal plants with aphids, which could explain the weight gain in aphids. We also identified novel candidate genes that are differentially expressed in nonmycorrhizal plants with aphids, thus setting the stage for future functional studies.

The Effects of Rhizophagus irregularis Inoculation on Transcriptome of Medicago lupulina Leaves at Early Vegetative and Flowering Stages of Plant Development

“…The advent of omics technologies has provided the possibility of quick and effective means of filling in the gaps related to difficulties in comparing data obtained at different developmental stages for different plant species. Special interest is always paid to the improvement of sequencing and transcriptome analyses [19][20][21][22][23]. Studies are underway investigating the influence of AM fungi on the proteome of M. truncatula, Pisum sativum [23][24][25][26][27], and on the metabolome (with gaschromatography-mass spectrometry, GC-MS) of M. truncatula, M. lupulina, P. sativum [26,[28][29][30][31][32], etc.…”