The nonpathogenic strain of Fusarium oxysporum FO12 induces Fe deficiency responses in cucumber (Cucumis sativus L.) plants

Abstract

Main conclusion FO12 strain enhances Fe deficiency responses in cucumber plants, probably through the production of ethylene and NO in the subapical regions of the roots. Abstract Rhizosphere microorganisms can elicit induced systemic resistance (ISR) in plants. This type of resistance involves complex mechanisms that confer protection to the plant against pathogen attack. Additionally, it has been reported by several studies that ISR and Fe deficiency responses are modulated by common pathways, involving some phytohormones and signaling molecules, like ethylene and nitric oxide (NO). The aim of this study was to determine whether the nonpathogenic strain of Fusarium oxysporum FO12 can induce Fe deficiency responses in cucumber (Cucumis sativus L.) plants. Our results demonstrate that the root inoculation of cucumber plants with the FO12 strain promotes plant growth after several days of cultivation, as well as rhizosphere acidification and enhancement of ferric reductase activity. Moreover, Fe-related genes, such as FRO1, IRT1 and HA1, are upregulated at certain times after FO12 inoculation either upon Fe-deficiency or Fe-sufficient conditions. Furthermore, it has been found that this fungus colonizes root cortical tissues, promoting the upregulation of ethylene synthesis genes and NO production in the root subapical regions. To better understand the effects of the FO12 strain on field conditions, cucumber plants were inoculated and cultivated in a calcareous soil under greenhouse conditions. The results obtained show a modification of some physiological parameters in the inoculated plants, such as flowering and reduction of tissue necrosis. Overall, the results suggest that the FO12 strain could have a great potential as a Fe biofertilizer and biostimulant.

Entomopathogenic Fungus-Related Priming Defense Mechanisms in Cucurbits Impact Spodoptera littoralis (Boisduval) Fitness

“…These results would indicate that M. brunneum priming affects not only ET biosynthesis but ET signaling, therefore making plants more sensitive to this hormone. These results are in concordance with those of Aparicio et al ( 78 ), who have studied several genes related to ET biosynthesis ( ACO1 and ACO3 ) and signaling ( EIN2 and EIN3 ) in cucumber roots in Fe-sufficient and -deficient plants inoculated with the nonpathogenic strain Fusarium oxysporum FO12 over 4 days and found a significant induction of the genes studied in inoculated plants at different times independently of the nutritional status.…”

“…In the case of EPF, priming could be a very interesting strategy as it is an added value for the fungal efficacy when used for pest control. Usually, microorganism inducers of ISR also promote plant growth and development ( 77 ) and favor Fe acquisition ( 18 , 78 – 83 ). In the present work, we show the ability of the EPF M. brunneum to trigger both SA- and JA/ET-dependent priming in cucumber and melon seedlings with lethal and sublethal effects on S. littoralis fed on primed plants.…”

“…Some of these ISR inducer microorganisms also promote plant growth and development ( 77 ) and favor Fe acquisition in plants ( 18 , 78 – 83 ). This is in part due to the common involvement of ET and nitric oxide (NO) in the regulation of both processes and because of the cross talk among ET and JA signaling pathways ( 52 ).…”

“…This is in part due to the common involvement of ET and nitric oxide (NO) in the regulation of both processes and because of the cross talk among ET and JA signaling pathways ( 52 ). The effect of these microorganisms on the improvement of Fe nutrition is related to their ability to upregulate key genes related to Fe acquisition, such as FIT , MYB72 , IRT1 , and FRO2 ( 18 , 52 , 77 , 78 ). On the other hand, MYB72, a key transcription factor (TF) in ISR activation, also participates in the regulation of the Fe deficiency responses through its interaction with FIT TF, a key regulator of Fe deficiency responses.…”

The Responses of a Grapevine Rhizosphere System to Mulching Using Amplicon Sequencing and Transcriptomic Analysis

“…The rhizosphere functions as the key zone for interactions between plants and soils; a dynamic zone that integrates energy exchange and nutrient cycling among plants, soil, and microbial communities [7,8]. Rhizosphere microorganisms play pivotal roles in plant growth, plant resistance to abiotic and biotic stresses, and plant yields and qualities [9][10][11]. Rhizosphere microbes influence many aspects of plant growth, including the circadian clock and nutrient levels [12,13].…”