Ornamental plant Pachystachys lutea as a source of promising endophytes for plant growth and phytoprotective activity

Endophytes are growth-promoting agents capable of synthesizing phytohormones, uptaking nutrients, and controlling pathogens. There is a strong potential to exploit them in the agriculture field like biofertilizers and biocontrol agents. In this work, we aimed to evaluate endophytic fungi isolated from Pachystachys lutea for their potential to solubilize phosphate, synthesise indole acetic acid (IAA), antagonize phytopathogens, and promote plant growth under greenhouse conditions. The phosphate solubilization efficiency was assessed on Pikovskaya’s agar medium. For analysis of IAA production, mycelia plugs of endophytes were cultured in Potato Dextrose Broth medium supplemented with L-tryptophan, with Salkowski Reagent, and the absorbance of the culture was measured. The antagonism evaluation of strain Alternaria sp. PL75 against phytopathogens was performed using the paired-culture technique. The promotion of plant growth provided by Alternaria sp. PL75 was evaluated in tomato plants. All strains evaluated were able to solubilize phosphate; however, the strain Alternaria sp. PL75 was the most effective (4.29). Two strains, Nemania sp. PL27 and Alternaria sp. PL75, produced 1.86 and 1.73 & 956;g mL-1 of IAA, respectively. In the antagonism assay, the endophyte Alternaria sp. PL75 and its fungal extract showed the best results against the pathogen Moniliophthora perniciosa. The greenhouse experiment result showed the endophyte Alternaria sp. PL75 increased the plantlets emergency speed index and the percentage of germination from 60 to 81.63%. It was also observed a statistical significance in the shoot length of the treated plants with the endophyte suspension (55.38 cm) compared to the control (41.67 cm).

ENZYMATIC AND ANTAGONIST ACTIVITY OF ENDOPHYTIC FUNGI FROM Sapindus saponaria L. (SAPINDACEAE) / Actividad enzimática y antagonista de los hongos endofíticos de Sapindus saponaria L. (Sapindaceae)

ABSTRACT Endophyte microorganisms have great biotechnological interest, with features applicable to different areas and are potentially useful in agriculture. The current study determines the biotechnological potential of endophytic fungi, isolated from leaves of Sapindus saponaria, to control phytopathogenic fungi and evaluate their enzyme production. Molecular taxonomy was performed by sequencing of the ITS1-5.8S-ITS2 ribosomal DNA region, identifying the genera Phomopsis, Sordariomycetes, Diaporthe, and Colletotrichum. In vitro antagonism against phytopathogens showed better results against Fusarium solani and provided inhibition indices between 41.8 % and 67.5 %. The endophytic strain SS81 (Diaporthe citri) presented the highest antagonism index against the pathogen. Against Glomerella sp. and Moniliophthora perniciosa, inhibition rates ranged between 18.7 % and 57.4 % and between 38.3 % and 64.8 %, respectively. Enzyme assays revealed that strain SS65 (Diaporthe sp.) produced 1.16 UI μmol/min of amylase; strain SS77 (Diaporthe sp.) produced 2.74 UI μmol/min of pectinase, and strain SS08 (Diaporthe sp.) produced 1.51 UI μmol/min of cellulase. Thus, the current study shows evidence the importance of isolated endophytes with phytoprotective properties of plants with medicinal properties as alternatives for biological control and natural sources of products with biotechnological interest.

RESUMEN Los microorganismos endofíticos tienen gran interés biotecnológico, con características aplicables a diferentes áreas y potencialmente útiles en la agricultura. El presente estudio determinó el potencial biotecnológico de los hongos endofíticos, aislados de las hojas de Sapindus saponaria, en el control de hongos fitopatógenos y evaluación de su producción de enzimática. La taxonomía molecular fue realizada por la secuencia de la región ITS1-5.8S-ITS2 del ADN ribosomal, identificando los géneros Phomopsis, Sordariomycetes, Diaporthe y Colletotrichum. El antagonismo in vitro contra fitopatógenos mostró mejores resultados contra Fusarium solani y proporcionó índices de inhibición de entre el 41,8 % y el 67,5 %. El linaje endofítico SS81 (Diaporthe citri) presentó el mayor índice de antagonismo contra los patógenos. Contra Glomerella sp. y Moniliophthora perniciosa, las tasas de inhibición variaron entre el 18,7 % y el 57,4 % y entre el 38,3 % y el 64,8 %, respectivamente. El ensayo enzimático reveló que el linaje SS65 (Diaporthe sp.) produjo 1,16 UI μmol / min de amilasa; el linaje SS77 (Diaporthe sp.) produjo 2,74 UI μmol / min de pectinasa; y el linaje SS08 (Diaporthe sp.) produjo 1,51 UI μmol / min de celulasa. Así, el presente estudio evidencia la importancia de los endófitos aislados con propiedades fitoprotectoras como alternativas para el control biológico y como fuentes naturales de productos con interés biotecnológico.