Pochonia chlamydosporia Isolate PC-170-Induced Expression of Marker Genes for Defense Pathways in Tomatoes Challenged by Different Pathogens

Pochonia chlamydosporia is a fungal parasite of nematode eggs. Studies have shown that some strains of Pochonia chlamydosporia can promote plant growth and induce plants’ systemic resistance to root-knot nematodes by colonizing in their roots. This study aimed to verify the effect of the PC-170 strain on tomato growth and systemic resistance. Split-root experiments were conducted to observe the systemic resistance induced by PC-170. To explore the defense pathway that was excited due to the colonization by PC-170, we tested the expression of marker genes for defense pathways, and used mutant lines to verify the role of plant defense pathways. Our results showed that PC-170 can colonize roots, and promotes growth. We found a role for jasmonic acid (JA) in modulating tomato colonization by PC-170. PC-170 can activate tomato defense responses to reduce susceptibility to infection by the root-knot nematode Meloidogyne incognita, and induced resistance to some pathogens in tomatoes. The marker genes of the defense pathway were significantly induced after PC-170 colonization. However, salicylic acid (SA)- and jasmonic acid (JA)-dependent defenses in roots were variable with the invasion of different pathogens. Defense pathways play different roles at different points in time. SA- and JA-dependent defense pathways were shown to cross-communicate. Different phytohormones have been involved in tomato plants’ responses against different pathogens. Our study confirmed that adaptive JA signaling is necessary to regulate PC-170 colonization and induce systemic resistance in tomatoes.

Colonización endofítica del hongo nematófago Pochonia chlamydosporia en cultivos de Solanaceae y Cucurbitaceae

Introducción. Las especies fúngicas del género Pochonia son importantes para el manejo de nematodos fitoparásitos. Algunas de ellas colonizan en forma endófita a sus hospedantes vegetales y les proporcionan adaptabilidad, bio-estimulación vegetal e inducción de resistencia; dichas ventajas son esenciales para la selección de cepas a utilizar en el bio-manejo de fitonematodos. Objetivo. Evaluar la colonización endofítica y la bio-estimulación vegetal por las cepas nematófagas IMI SD 187 y 193 de P. chlamydosporia sobre especies hortícolas de las familias Solanaeceae y Cucurbitaceae. Materiales y métodos. El experimento se realizó dentro de invernaderos en el Centro Nacional de Sanidad Agropecuaria, provincia Mayabeque, Cuba. Se utilizaron dos cepas de P. chlamydosporia, denominadas IMI SD 187 y 193, así como tomate (S. lycopersicum) cv. HA 3057, pimiento (Capsicum annuum L.) cv. Grandísimo, pepino (Cucumis sativus L.) cv. INIVIT P 2007 y melón (Cucumis melo L.) cv. Zest F1. En ambas cepas se evaluó la colonización endofítica, del sustrato y de la raíz, así como algunos parámetros del crecimiento de las plantas. Resultados. Las cepas evaluadas colonizaron entre 3 y 16 % el interior de las raíces. La cepa IMI SD 187 colonizó a todas las especies evaluadas, mientras que 193 no pudo colonizar al melón; sin embargo, ambas cepas colonizaron la raíz y el sustrato con valores entre 2x103 y 2x104 UFC g-1, respectivamente. IMI SD 187 alcanzó los mayores valores de bio-estimulación en longitud y masa fresca de las raíces en pimiento. Conclusión. Las dos cepas autóctonas de P. chamydosporia colonizaron a las especies estudiadas y la mayor bio-estimulación del crecimiento se obtuvo con IMI SD 187 en el cultivar de pimiento.

A modified semi-selective medium for isolation and enumeration of Pochonia chlamydosporia (Goddard) Zare & W. Gams

Pochonia chlamydosporia, is one of the most promising biological control agents for managing phytoparasitic nematodes. Isolation and enumeration of viable colonies of P. chlamydosporia from soil and other substrates without contamination is a major limitation, when commonly available nutrient media are used. Development of a suitable selective/semi-selective media by incorporating one or more inhibitors of microbial growth can facilitate isolation of the fungus. In vitro studies were carried out to test the compatibility of commonly used pesticides, namely, metalaxyl, metalaxyl-mancozeb, carbendazim, copper oxychloride, and chlorpyrifos with P. chlamydosporia. The fungus showed relatively high tolerance to higher doses of metalaxyl and carbendazim and was used in the modified medium for better suppression of other soil borne fungi. In the present study, Kerry’s semi-selective medium was modified and evaluated by counting the viable fungal propagules in different substrates (rice, farmyard manure, maize, rice bran, barley, and sorghum) and soil artificially inoculated with the fungus. The results showed that the modified Kerry’s semi-selective medium can effectively be used for isolation and quantification of P. chlamydosporia in routine studies.

QUANTIFICATION OF DAMAGE AND YIELD LOSSES AND MANAGEMENT OF ROOT-KNOT NEMATODES IN CONILON COFFEE

ABSTRACT Commercial exploitation of the coffee crop is one of the most important activities in the world’s agricultural sector. One of the main phytosanitary problems affecting the crop is the presence of Meloidogyne incognita. Several measures have been tested for the management of this pathogen, albeit with low efficiency. The objective of this work was to quantify the damage and losses and to manage M. incognita race 1 with Pochonia chlamydosporia and Trichoderma harzianum biological nematicides, comparing them to a chemical nematicide. The experiment was carried out in a commercial area naturally infested by the nematode and cultivated with the conilon coffee variety ‘Vitória INCAPER 8142’, clone V02. The treatments were tested with Carbofuran nematicide and with biological nematicides composed of P. chlamydosporia Pc-10 and T. harzianum ESALQ 1306. The biological products were applied alone or in combination. The lowest NPF (final nematode population) occurred in plants treated with P. chlamydosporia and Carbofuran. P. chlamydosporia was the most effective biological agent in the management of M. incognita. There was a reduction in production with an increase in the nematode population. The highest application costs of management methods for M. incognita race 1 per hectare were for three and two applications of Carbofuran and three applications of P. chlamydosporia + T. harzianum. The treatments with lowest application costs were one application of T. harzianum and one application of P. chlamydosporia. It was concluded that all treatments were efficient for the management of M. incognita race 1, causing a decrease in the roots and soil population.

Airborne Fungi in Show Caves from Southern Spain

The aerobiology of caves in Southern Spain possesses special characteristics, different from caves located in Northern Spain. Previous studies demonstrated the influence of outdoor air on caves in the north and the existence of two different patterns, depending on the season. In summer there is an abundance of Ascomycota, whereas in winter Basidiomycota predominates, which are related to the periods of stagnation and ventilation, respectively. In caves in Southern Spain the presence of airborne Basidiomycota is scarce and Ascomycota represents the main group of fungi widely distributed across the caves in all seasons. The most characteristic features were the abundant presence of entomopathogenic fungi (Beauveria bassiana, Parengyodontium album, Pochonia chlamydosporia, Leptobacillium symbioticum, Leptobacillium leptobactrum) and Cladosporium cladosporioides in Cueva del Tesoro, Cueva de Ardales and Gruta de las Maravillas. However, the presence of yeasts of the genera Cutaneotrichosporon, Trichosporon, Cryptococcus, Naganishia, Cystobasidium, Microstroma and Phragmotaenium was exclusive to Gruta de las Maravillas. Fungal hazard in the three show caves were determined using an ecological indicator based on the concentration of spores in cave air.