Serendipita fungi modulate the switchgrass root transcriptome to circumvent host defenses and establish a symbiotic relationship

The fungal family Serendipitaceae encompasses root-associated lineages with endophytic, ericoid, orchid and ectomycorrhizal lifestyles. Switchgrass is an important bioenergy crop for cellulosic ethanol production owing to high biomass production on marginal soils otherwise unfit for food crop cultivation. The aim of this study was to investigate the host plant response(s) to Serendipita colonization by characterizing the switchgrass root transcriptome during different stages of symbiosis in vitro. For this, we included a native switchgrass strain, Serendipita bescii, and a related strain Serendipita vermifera isolated from Australian orchids. Serendipita colonization progresses from thin hyphae that grow between root cells, and finally the production of large, bulbous hyphae that fill root cells during the later stages of colonization. We report that switchgrass seems to perceive both fungi prior to physical contact, leading to the activation of chemical and structural defense responses and putative host disease resistance genes. Subsequently, the host defense system appears to be quenched and carbohydrate metabolism adjusted, potentially to accommodate the fungal symbiont. In addition, prior to contact, switchgrass exhibited significant increases in root hair density and root surface area. Further, genes involved in phytohormone metabolism, such as gibberellin, jasmonic acid and salicylic acid were activated during different stages of colonization. Both fungal strains induced plant gene expression in a similar manner, indicating a conserved plant response to members of this fungal order. Understanding plant responsiveness to Serendipita will inform our efforts to integrate them into forages and row crops for optimal plant-microbe functioning, thus facilitating low-input, sustainable agricultural practices.

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Evaluation of tooth root surface area using a three-dimensional scanning technique and cone beam computed tomographic reconstruction in vitro

Archives of Oral Biology ◽

10.1016/j.archoralbio.2017.07.014 ◽

2017 ◽

Vol 84 ◽

pp. 13-18

Author(s):

Tong Wang ◽

Xibo Pei ◽

Feng Luo ◽

Lingling Jia ◽

Han Qin ◽

...

Keyword(s):

Surface Area ◽

Tomographic Reconstruction ◽

Three Dimensional ◽

Root Surface ◽

Cone Beam ◽

Root Surface Area ◽

Tooth Root ◽

Computed Tomographic ◽

Scanning Technique

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Transcriptional Changes in Mycorrhizal and Nonmycorrhizal Soybean Plants upon Infection with the Fungal Pathogen Macrophomina phaseolina

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-11-17-0282-r ◽

2018 ◽

Vol 31 (8) ◽

pp. 842-855 ◽

Cited By ~ 6

Author(s):

Nathalie Marquez ◽

María L. Giachero ◽

Adrien Gallou ◽

Humberto J. Debat ◽

Sylvie Cranenbrouck ◽

...

Keyword(s):

Mycorrhizal Fungi ◽

Fungal Pathogen ◽

Negative Impact ◽

Genetic Resistance ◽

Agricultural Practices ◽

Integrated Approach ◽

Macrophomina Phaseolina ◽

Defense Responses ◽

Transcriptional Changes

Macrophomina phaseolina is a soil-borne fungal pathogen with a wide host range that causes charcoal rot in soybean [Glycine max (L.) Merr.]. Control of the disease is a challenge, due to the absence of genetic resistance and effective chemical control. Alternative or complementary measures are needed, such as the use of biological control agents, in an integrated approach. Several studies have demonstrated the role of arbuscular mycorrhizal fungi (AMF) in enhancing plant resistance or tolerance to biotic stresses, decreasing the symptoms and pressure caused by various pests and diseases, including M. phaseolina in soybean. However, the specific contribution of AMF in the regulation of the plant response to M. phaseolina remains unclear. Therefore, the objective of the present study was to investigate, under strict in-vitro culture conditions, the global transcriptional changes in roots of premycorrhized soybean plantlets challenged by M. phaseolina (+AMF+Mp) as compared with nonmycorrhizal soybean plantlets (−AMF+Mp). MapMan software was used to distinguish transcriptional changes, with special emphasis on those related to plant defense responses. Soybean genes identified as strongly upregulated during infection by the pathogen included pathogenesis-related proteins, disease-resistance proteins, transcription factors, and secondary metabolism–related genes, as well as those encoding for signaling hormones. Remarkably, the +AMF+Mp treatment displayed a lower number of upregulated genes as compared with the −AMF+Mp treatment. AMF seemed to counteract or balance costs upon M. phaseolina infection, which could be associated to a negative impact on biomass and seed production. These detailed insights in soybean-AMF interaction help us to understand the complex underlying mechanisms involved in AMF-mediated biocontrol and support the importance of preserving and stimulating the existing plant-AMF associates, via adequate agricultural practices, to optimize their agro-ecological potential.

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Phytase-Producing Rahnella aquatilis JZ-GX1 Promotes Seed Germination and Growth in Corn (Zea mays L.)

Microorganisms ◽

10.3390/microorganisms9081647 ◽

2021 ◽

Vol 9 (8) ◽

pp. 1647

Author(s):

Gui-E Li ◽

Wei-Liang Kong ◽

Xiao-Qin Wu ◽

Shi-Bo Ma

Keyword(s):

Seed Germination ◽

Plant Growth ◽

Biomass Accumulation ◽

Root Surface ◽

Phosphorus Concentration ◽

Maize Seedlings ◽

Total Phosphorus Concentration ◽

Rahnella Aquatilis ◽

Maize Seeds

Phytase plays an important role in crop seed germination and plant growth. In order to fully understand the plant growth-promoting mechanism by Rahnella aquatilis JZ-GX1，the effect of this strain on germination of maize seeds was determined in vitro, and the colonization of maize root by R. aquatilis JZ-GX1 was observed by scanning electron microscope. Different inoculum concentrations and Phytate-related soil properties were applied to investigate the effect of R. aquatilis JZ-GX1 on the growth of maize seedlings. The results showed that R. aquatilis JZ-GX1 could effectively secrete indole acetic acid and had significantly promoted seed germination and root length of maize. A large number of R. aquatilis JZ-GX1 cells colonized on the root surface, root hair and the root interior of maize. When the inoculation concentration was 107 cfu/mL and the insoluble organophosphorus compound phytate existed in the soil, the net photosynthetic rate, chlorophyll content, phytase activity secreted by roots, total phosphorus concentration and biomass accumulation of maize seedlings were the highest. In contrast, no significant effect of inoculation was found when the total P content was low or when inorganic P was sufficient in the soil. R. aquatilis JZ-GX1 promotes the growth of maize directly by secreting IAA and indirectly by secreting phytase. This work provides beneficial information for the development and application of R. aquatilis JZ-GX1 as a microbial fertilizer in the future.

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A peroxisomal β-oxidative pathway contributes to the formation of C6–C1 aromatic volatiles in poplar

Plant Physiology ◽

10.1093/plphys/kiab111 ◽

2021 ◽

Author(s):

Nathalie D Lackus ◽

Axel Schmidt ◽

Jonathan Gershenzon ◽

Tobias G Köllner

Keyword(s):

Cinnamic Acid ◽

Aromatic Compounds ◽

Populus Trichocarpa ◽

Alternative Pathway ◽

Gene Families ◽

Defense Responses ◽

In Planta ◽

Black Cottonwood ◽

Oxidative Pathway

AbstractBenzenoids (C6–C1 aromatic compounds) play important roles in plant defense and are often produced upon herbivory. Black cottonwood (Populus trichocarpa) produces a variety of volatile and nonvolatile benzenoids involved in various defense responses. However, their biosynthesis in poplar is mainly unresolved. We showed feeding of the poplar leaf beetle (Chrysomela populi) on P. trichocarpa leaves led to increased emission of the benzenoid volatiles benzaldehyde, benzylalcohol, and benzyl benzoate. The accumulation of salicinoids, a group of nonvolatile phenolic defense glycosides composed in part of benzenoid units, was hardly affected by beetle herbivory. In planta labeling experiments revealed that volatile and nonvolatile poplar benzenoids are produced from cinnamic acid (C6–C3). The biosynthesis of C6–C1 aromatic compounds from cinnamic acid has been described in petunia (Petunia hybrida) flowers where the pathway includes a peroxisomal-localized chain shortening sequence, involving cinnamate-CoA ligase (CNL), cinnamoyl-CoA hydratase/dehydrogenase (CHD), and 3-ketoacyl-CoA thiolase (KAT). Sequence and phylogenetic analysis enabled the identification of small CNL, CHD, and KAT gene families in P. trichocarpa. Heterologous expression of the candidate genes in Escherichia coli and characterization of purified proteins in vitro revealed enzymatic activities similar to those described in petunia flowers. RNA interference-mediated knockdown of the CNL subfamily in gray poplar (Populus x canescens) resulted in decreased emission of C6–C1 aromatic volatiles upon herbivory, while constitutively accumulating salicinoids were not affected. This indicates the peroxisomal β-oxidative pathway participates in the formation of volatile benzenoids. The chain shortening steps for salicinoids, however, likely employ an alternative pathway.

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Effects of Ridge Tillage and Straw Mulching on Cultivation the Fresh Faba Beans

Agronomy ◽

10.3390/agronomy11061054 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1054

Author(s):

Bo Li ◽

Xinyu Chen ◽

Xiaoxu Shi ◽

Jian Liu ◽

Yafeng Wei ◽

...

Keyword(s):

Rice Straw ◽

Precision Agriculture ◽

Field Experiments ◽

Root Length Density ◽

Root Surface ◽

High Yield ◽

Root Surface Area ◽

Straw Mulching ◽

Faba Beans ◽

Ridge Tillage

Ridge tillage is an effective agronomic practice and a miniature precision agriculture; however, its effects on the growth of faba beans (Vicia faba L.) are poorly understood. This study aimed to determine the effect of ridge tillage and straw mulching on the root growth, nutrient accumulation and yield of faba beans. Field experiments were conducted during 2016 and 2017 cropping seasons and comprised four treatments: ridge tillage without any mulching (RT), flat tillage without any mulch (FT), flat tillage with rice straw mulched on the ridge tillage (FTRSM) and ridge tillage with rice straw mulched on the ridge tillage (RTRSM). The RT and RTRSM increased soil temperature and decreased soil humidity and improved soil total nitrogen, total phosphorus, available potassium and organic matter. RT and RTRSM increased the root length density, root surface area, root diameter and root activity of faba beans at flowering and harvest periods. The RT and RTRSM also increased the nitrogen, phosphorus, potassium absorption and the yield of faba beans. These results indicated that ridge tillage and straw mulching affect faba bean growth by improving soil moisture conditions and providing good air permeability and effective soil nutrition supply. This study provides a theoretical basis for the high yield cultivation improvement of faba beans.

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