scholarly journals Synergy of arbuscular mycorrhizal symbiosis and exogenous Ca2+ benefits peanut (Arachis hypogaea L.) growth through the shared hormone and flavonoid pathway

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Li Cui ◽  
Feng Guo ◽  
Jialei Zhang ◽  
Sha Yang ◽  
JingJing Meng ◽  
...  

Abstract Peanut yield is severely affected by exchangeable calcium ion (Ca2+) deficiency in the soil. Arbuscular mycorrhizal (AM) symbiosis increases the absorption of Ca2+ for host plants. Here, we analyzed the physiological and transcriptional changes in the roots of Arachis hypogaea L. colonized by Funneliformismosseae under Ca2+-deficient and -sufficient conditions. The results showed that exogenous Ca2+ application increased arbuscular mycorrhizal fungi (AMF) colonization, plant dry weight, and Ca content of AM plants. Simultaneously, transcriptome analysis showed that Ca2+ application further induced 74.5% of differentially expressed gene transcripts in roots of AM peanut seedlings. These genes are involved in AM symbiosis development, hormone biosynthesis and signal transduction, and carotenoid and flavonoid biosynthesis. The transcripts of AM-specific marker genes in AM plants with Ca2+ deprivation were further up-regulated by Ca2+ application. Gibberellic acid (GA3) and flavonoid contents were higher in roots of AM- and Ca2+-treated plants, but salicylic acid (SA) and carotenoid contents specifically increased in roots of the AM plants. Thus, these results suggest that the synergy of AM symbiosis and Ca2+ improves plant growth due to the shared GA- and flavonoid-mediated pathway, whereas SA and carotenoid biosynthesis in peanut roots are specific to AM symbiosis.

Viruses ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 675
Author(s):  
Laura Miozzi ◽  
Anna Maria Vaira ◽  
Federico Brilli ◽  
Valerio Casarin ◽  
Mara Berti ◽  
...  

Tomato plants can establish symbiotic interactions with arbuscular mycorrhizal fungi (AMF) able to promote plant nutrition and prime systemic plant defenses against pathogens attack; the mechanism involved is known as mycorrhiza-induced resistance (MIR). However, studies on the effect of AMF on viral infection, still limited and not conclusive, indicate that AMF colonization may have a detrimental effect on plant defenses against viruses, so that the term “mycorrhiza-induced susceptibility” (MIS) has been proposed for these cases. To expand the case studies to a not yet tested viral family, that is, Bromoviridae, we investigated the effect of the colonization by the AMF Funneliformis mosseae on cucumber mosaic virus (CMV) infection in tomato by phenotypic, physiological, biochemical, and transcriptional analyses. Our results showed that the establishment of a functional AM symbiosis is able to limit symptoms development. Physiological and transcriptomic data highlighted that AMF mitigates the drastic downregulation of photosynthesis-related genes and the reduction of photosynthetic CO2 assimilation rate caused by CMV infection. In parallel, an increase of salicylic acid level and a modulation of reactive oxygen species (ROS)-related genes, toward a limitation of ROS accumulation, was specifically observed in CMV-infected mycorrhizal plants. Overall, our data indicate that the AM symbiosis influences the development of CMV infection in tomato plants and exerts a priming effect able to enhance tolerance to viral infection.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manoj-Kumar Arthikala ◽  
Kalpana Nanjareddy ◽  
Lourdes Blanco ◽  
Xóchitl Alvarado-Affantranger ◽  
Miguel Lara

AbstractTarget of rapamycin (TOR) is a conserved central growth regulator in eukaryotes that has a key role in maintaining cellular nutrient and energy status. Arbuscular mycorrhizal (AM) fungi are mutualistic symbionts that assist the plant in increasing nutrient absorption from the rhizosphere. However, the role of legume TOR in AM fungal symbiosis development has not been investigated. In this study, we examined the function of legume TOR in the development and formation of AM fungal symbiosis. RNA-interference-mediated knockdown of TOR transcripts in common bean (Phaseolus vulgaris) hairy roots notably suppressed AM fungus-induced lateral root formation by altering the expression of root meristem regulatory genes, i.e., UPB1, RGFs, and sulfur assimilation and S-phase genes. Mycorrhized PvTOR-knockdown roots had significantly more extraradical hyphae and hyphopodia than the control (empty vector) roots. Strong promoter activity of PvTOR was observed at the site of hyphal penetration and colonization. Colonization along the root length was affected in mycorrhized PvTOR-knockdown roots and the arbuscules were stunted. Furthermore, the expression of genes induced by AM symbiosis such as SWEET1, VPY, VAMP713, and STR was repressed under mycorrhized conditions in PvTOR-knockdown roots. Based on these observations, we conclude that PvTOR is a key player in regulating arbuscule development during AM symbiosis in P. vulgaris. These results provide insight into legume TOR as a potential regulatory factor influencing the symbiotic associations of P. vulgaris and other legumes.


Botany ◽  
2014 ◽  
Vol 92 (4) ◽  
pp. 241-251 ◽  
Author(s):  
Ylva Lekberg ◽  
Roger T. Koide

Our knowledge of arbuscular mycorrhizal (AM) function is largely based on results from short-term studies in controlled environments. While these have provided many important insights into the potential effects of the symbiosis on the two symbionts and their communities, they may have also inadvertently led to faulty assumptions about the function of the symbiosis in natural settings. Here we highlight the consequences of failing to consider the AM symbiosis from the perspectives of community ecology and evolutionary biology. Also, we argue that by distinguishing between physiological and evolutionary viewpoints, we may be able to resolve controversies regarding the mutualistic vs. parasitic nature of the symbiosis. Further, while most AM research has emphasized resource transfers, primarily phosphate and carbohydrate, our perceptions of parasitism, cheating, bet-hedging, and partner choice would most likely change if we considered other services. Finally, to gain a fuller understanding of the role of the AM symbiosis in nature, we need to better integrate physiological processes of plants and their AM fungi with their naturally occurring temporal and spatial patterns. It is our hope that this article will generate some fruitful discussions and make a contribution toward this end.


2021 ◽  
Vol 7 (8) ◽  
pp. 671
Author(s):  
Xiao Lou ◽  
Xiangyu Zhang ◽  
Yu Zhang ◽  
Ming Tang

The simultaneous effects of arbuscular mycorrhizal (AM) fungi and abscisic acid (ABA) on the tolerance of plants to heavy metal (HM) remain unclear. A pot experiment was carried out to clarify the effects of simultaneous applications of AM fungi and ABA on plant growth, Zn accumulation, endogenous ABA contents, proline metabolism, and the oxidative injury of black locust (Robinia pseudoacacia L.) exposed to excess Zn stress. The results suggested that exogenously applied ABA positively enhanced AM colonization, and that the growth of plants only with AM fungi was improved by ABA application. Under Zn stress, AM inoculation and ABA application increased the ABA content in the root/leaf (increased by 48–172% and 92%, respectively) and Zn content in the root/shoot (increased by 63–152% and 61%, respectively) in AM plants, but no similar trends were observed in NM plants. Additionally, exogenous ABA addition increased the proline contents of NM roots concomitantly with the activities of the related synthases, whereas it reduced the proline contents and the activity of Δ1-pyrroline-5-carboxylate synthetase in AM roots. Under Zn stress, AM inoculation and ABA application decreased H2O2 contents and the production rate of O2, to varying degrees. Furthermore, in the roots exposed to Zn stress, AM inoculation augmented the activities of SOD, CAT, POD and APX, and exogenously applied ABA increased the activities of SOD and POD. Overall, AM inoculation combined with ABA application might be beneficial to the survival of black locust under Zn stress by improving AM symbiosis, inhibiting the transport of Zn from the roots to the shoots, increasing the distribution of ABA in roots, and stimulating antioxidant defense systems.


2018 ◽  
Author(s):  
Ivan D. Mateus ◽  
Frédéric G. Masclaux ◽  
Consolée Aletti ◽  
Edward C. Rojas ◽  
Romain Savary ◽  
...  

AbstractArbuscular mycorrhizal fungi (AMF) impact plant growth and are a major driver of plant diversity and productivity. We quantified the contribution of intra-specific genetic variability in cassava (Manihot esculenta) and Rhizophagus irregularis to gene reprogramming in symbioses using dual RNA-sequencing. A large number of cassava genes exhibited altered transcriptional responses to the fungus but transcription of most of these plant genes (72%) responded in a different direction or magnitude depending on the plant genotype. Two AMF isolates displayed large differences in their transcription, but the direction and magnitude of the transcriptional responses for a large number of these genes was also strongly influenced by the genotype of the plant host. This indicates that unlike the highly conserved plant genes necessary for the symbiosis establishment, plant and fungal gene transcriptional responses are not conserved and are greatly influenced by plant and fungal genetic differences, even at the within-species level. The transcriptional variability detected allowed us to identify an extensive gene network showing the interplay in plant-fungal reprogramming in the symbiosis. Key genes illustrated that the two organisms jointly program their cytoskeleton organisation during growth of the fungus inside roots. Our study reveals that plant and fungal genetic variation plays a strong role in shaping the genetic reprograming in response to symbiosis, indicating considerable genotype x genotype interactions in the mycorrhizal symbiosis. Such variation needs to be considered in order to understand the molecular mechanisms between AMF and their plant hosts in natural communities.


2010 ◽  
Vol 67 (6) ◽  
pp. 692-701 ◽  
Author(s):  
Edmilson José Ambrosano ◽  
Rozario Azcón ◽  
Heitor Cantarella ◽  
Gláucia Maria Bovi Ambrosano ◽  
Eliana Aparecida Schammass ◽  
...  

A cana-de-açúcar (Saccharum spp.) vem sendo cultivada no Brasil para produção de açúcar e agroenergia. Em seu sistema de produção, após um ciclo de 4 a 8 anos, é possível a rotação com plantas de cobertura, antes do seu replantio, para melhoria do solo e geração de renda. Estudou-se a caracterização e produtividade de biomassa de leguminosas (como adubos-verdes) e girassol (Helianthus annuus L.), a ocorrência natural de micorrizas, o teor de açúcar e a produtividade em colmos da cana-de-açúcar IAC 87-3396 e a viabilidade econômica desse sistema com cultivo após as opções de rotação, com quantificação da produtividade durante três cortes consecutivos. O amendoim (Arachis hypogaea L.) cv. IAC-Caiapó, girassol cv. IAC-Uruguai e mucuna-preta (Mucuna aterrimum Piper and Tracy) foram as culturas que apresentaram maior percentagem de colonização por fungos micorrízicos. O girassol foi a planta de cobertura que mais extraiu nutrientes do solo, seguido por amendoim (Arachis hipogaea L.) cv. IAC-Tatu e feijão-mungo (Vigna radiata L. Wilczek). A colonização por fungos micorrízicos mostrou correlação positiva com a altura de plantas de cana no primeiro corte (p = 0,01 e R = 0,52), mas não se correlacionou com a produtividade de colmos ou açúcar. No primeiro corte, o girassol foi a cultura de rotação que ocasionou o maior aumento de produtividade, da ordem de 46% em colmos e de 50% na quantidade de açúcar, em comparação com a testemunha. Com exceção dos amendoins, todas as culturas em rotação aumentaram a renda líquida do sistema na média de três cortes de cana-de-açúcar.


2018 ◽  
Vol 46 (1) ◽  
pp. 270-276 ◽  
Author(s):  
Fei ZHANG ◽  
Jia-Dong HE ◽  
Qiu-Dan NI ◽  
Qiang-Sheng WU ◽  
Ying-Ning ZOU

Sucrose and proline metabolisms are often associated with drought tolerance of plants. This study was conducted to investigate the effects of two arbuscular mycorrhizal fungi (AMF) species (Funneliformis mosseae and Paraglomus occultum) on root biomass, lateral root number, root sucrose and proline metabolisms in trifoliate orange (Poncirus trifoliata) seedlings under well-watered (WW) or drought stress (DS). All the AMF treatments significantly increased root dry weight, taproot length, and the number of lateral roots in 1st, 2nd, and 3rd class under WW and DS. Mycorrhizal seedlings conferred considerably higher fructose and glucose concentrations but lower sucrose accumulation, regardless of soil water status. Under DS, F. mosseae treatment significantly increased root sucrose synthase (SS, degradative direction) and sucrose phosphate synthase (SPS) activity but deceased root acid invertase (AI) and neutral invertase (NI) activity, and P. occultum inoculation markedly increased root AI, NI, SS, and SPS activities. AMF treatments led to a lower proline accumulation in roots, in company with lower activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS), δ-ornithine aminotransferase (OAT), Δ1-pyrroline-5-carboxylate reductase (P5CR), and proline dehydrogenase (ProDH) in roots. It appears that the AM symbiosis induced greater root development and sucrose and proline metabolisms to adapt DS.


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