Endophytic effects of Aspergillus oryzae on radish (Raphanus sativus) and its herbivore, Plutella xylostella

Abstract

We provide evidence that Aspergillus oryzae not only acts as an endophyte in Raphanus sativus, but also works as a plant growth promoter and provides some protection against its herbivore, Plutella xylostella affecting its feeding rate, mortality and fitness parameters, thereby contributing to the pest population suppression. Seed inoculation of radish seeds with the fungus Aspergillus oryzae allowed its establishment as an endophyte promoting plant growth and negatively affecting fitness parameters of its major herbivore, diamondback moth, Plutella xylostella. Endophytic fungi may contribute to the growth of their host plants and enhance resistance to herbivores and diseases. We evaluated the effect of A. oryzae (Ahlburg) E. Cohn as an endophyte in radish (Raphanus sativus L.) on growth and development of the plants themselves and their major herbivore, the diamondback moth P. xylostella (L). A. oryzae colonization rates in leaves were significantly higher than in roots and stems, with a rate of 80% in leaves, 40% in stems and 20% in roots 1 week after seed inoculation. Colonization gradually decreased in the various plant tissues, and disappeared completely in roots, stems and leaves within 2, 5 and 7 weeks, respectively. A. oryzae did not affect seed germination; however, it promoted radish growth with endophytic plants attaining average heights of 116 mm compared to 99.6 mm in the controls at the third week post-inoculation. The P. xylostella fitness parameters, consumption, larval and pupal weights, and feeding on the endophytic plants were significantly lower than the controls, while larval mortality was significantly higher. Larvae fed on endophytic plants consumed 0.46 mg less leaf matter in the first week post seed inoculation and weighed 0.83 mg less as mature 4th instars than controls. We have demonstrated that A. oryzae can establish as an endophyte in R. sativus through seed inoculation providing some plant growth promotion and protection against its herbivore by increasing its mortality and negatively affecting its fitness parameters, suggesting that adopting seed treatments with A. oryzae may be beneficial in the commercial cultivation of radish.

Transcriptional Reprogramming of Arabidopsis thaliana Defence Pathways by the Entomopathogen Beauveria bassiana Correlates With Resistance Against a Fungal Pathogen but Not Against Insects

“…It is also conceivable that handling the small delicate insects with a soft paintbrush, despite taking great care, might have had some adverse effects. Baseline mortality of P. xylostella seems to vary considerably between 10 and 43% (Haas et al, 2018; Sun et al, 2018). Nevertheless, both endophyte strains caused a significant decrease in the area of necrotic leaf lesions by S. sclerotiorum .…”

Endophytic Colonisation of Solanum lycopersicum and Phaseolus vulgaris by Fungal Endophytes Promotes Seedlings Growth and Hampers the Reproductive Traits, Development, and Survival of the Greenhouse Whitefly, Trialeurodes vaporariorum

“…As highlighted by Mayerhofer et al (2013), the contrasts in the results for the growth parameters in which different hosts respond differently to the same endophyte can be attributed to host specificity and may not be reproducible for all hosts. Other examples where endophyte inoculation did not result in enhanced plant growth are cacao (Hanada et al, 2010), tomato (Wei et al, 2020), radish (Sun et al, 2018), and sorghum (Tefera and Vidal, 2009).…”

“…The fresh and dry shoot weights were also measured only in the final week to assess the total accumulated shoot biomass for the entire growing period. The dry shoot weight was measured by cutting off 2 cm above the base of the pseudostem, and drying the shoots in a hot air oven at 60 • C for 48 h (Akello et al, 2007;Sun et al, 2018).…”

“…Endophytes stimulate the synthesis of secondary metabolites such as terpenoids, phenols, and phytoalexins volatile oils which confer resistance to several insects, resulting in the deterrence of feeding, oviposition, stem boring, sap sucking, and leaf mining by pests (Gao et al, 2011;Kambrekar, 2016;Agbessenou et al, 2020). The systemic effect of endophytes against insects has been shown in several other insects including diamondback moth [Plutella xylostella (L.)] (Lepidoptera: Plutellidae) (Batta, 2013;Sun et al, 2018), Silverleaf whitefly (B. tabaci) (Gennadius) (Hemiptera: Aleyrodidae) (Garrido-Jurado et al, 2017), pea leafminer (Liriomyza huidobrensis) (Blanchard) (Diptera: Agromyzidae) (Akutse et al, 2013), tomato leafminer (Tuta absoluta) (Meyrick) (Lepidoptera: Gelechiidae) (Klieber and Reineke, 2016;Agbessenou et al, 2020), cotton aphid (Aphis gossypii) (Glover) (Homoptera: Aphididae) (Lopez et al, 2014), mealybugs (Planococcus ficus) (Signoret) (Hemiptera: Pseudococcidae) (Rondot and Reineke, 2018), and spider mites (Tetranychus urticae) (Koch) (Acari: Tetranychidae) (Pappas et al, 2018). Another additional benefit from some endophytes is their potential to promote plant growth (Mayerhofer et al, 2013;Hassan, 2017;Bamisile et al, 2018aBamisile et al, ,b, 2020Russo et al, 2019).…”

Fungal Endophyte Communities of Crucifer Crops Are Seasonally Dynamic and Structured by Plant Identity, Plant Tissue and Environmental Factors

“…Furthermore, two of these endophyte species appeared in all parts of the plant, eight in two parts of the plant and 30 only in one part (Zhang et al, 2014). The colonization of specific plant tissues is based on their utilization of specific substrate that occur in that plant part (Rodrigues, 1994), while some endophytes can colonize the whole plant (Sun et al, 2018).…”