Trichodermaspp. as elicitors of wheat plant defense responses againstSeptoria tritici

Abstract

Leaf blotch of wheat is a widespread and highly active disease that affects wheat production. In addition to the use of chemicals and proper cultivation methods, microbial antagonists are used to control plant pathogens. Trichoderma spp. stimulate a systemic induced response in plants. Therefore, the efficacy of Trichoderma spp. against wheat leaf blotch was evaluated under greenhouse conditions. The susceptible plants were sprayed with Septoria tritici conidiospores. In order to select an efficient method of pretreatment with Trichoderma spp., leaf spraying and seed coating with 14 isolates were tested in 2003 and 2004. The extent of leaf necrosis area and pycnidial coverage was estimated. Antagonism was assessed by the capacity of each Trichoderma spp. isolate to restrict the progress of leaf blotch, 21 days after inoculation. Of the two methods, seed coating was more efficacious against leaf blotch than leaf spraying. Amongst the 14 isolates tested, the isolate prepared from T. harzianum (Th5) produced the highest level of protection. None of the treatments caused changes in plant stem diameter or dry weight. Trichoderma spp. did not get into leaves while S. tritici was present, even in asymptomatic leaf extracts. In addition, the leaf apoplast antifungal proteolytic activity was measured in plants 7, 15, and 22 days after sowing. This antifungal action decreased in plants only inoculated with S. tritici , but increased in those grown from seeds coated with the T. harzianum (Th5) isolate. This increase conferred resistance to the susceptible wheat cultivar. The endogenous germin-like protease inhibitor coordinated the proteolytic action. These results suggest that T. harzianum stimulates a biochemical systemic induced response against leaf blotch.

Effect of Trichoderma spp. isolates for biological control of tan spot of wheat caused by Pyrenophora tritici-repentis under field conditions in Argentina

“…The isolates T5 (Trichoderma harzianum) and T6 (T. koningii) were originally obtained from wheat phylloplane and parasited sclerotia from Sclerotinia sclerotiorum respectively. T. harzianum has previously been reported as a biocontrol agent in the aerial environment on different crops including other wheat diseases (Cordo et al 2007;Elad 2000;Hermosa et al 2000;Mónaco et al 2004;Perello et al 1997Perello et al , 2003. Previous assays in Argentina have demonstrated that some T. harzianum isolates were capable of suppressing growth and mycelial development of PTR and the severity of disease on wheat plants (Perelló et al 2003(Perelló et al , 2006.…”

Germin and Germin-like Proteins: Evolution, Structure, and Function

“…More recently, a maize protein ZmGLP1 with sequence similarity to the barley GLP with AGPPase activity has also been reported (Fan et al, 2005). Additionally, a GLP which inhibits serine protease activity has been reported in the wheat apoplast and suggested to be part of a defense system against insect and bacterial proteases (Segarra et al, 2003;Cordo et al, 2007). Such biotic responses are discussed below.…”

Fungicida biológico a base de una cepa del hongo Trichoderma harzianum: su supervivencia en el suelo

“…En concordancia con Mukhopadhyay et al, (1992) un método efectivo para incorporar el antagonista es recubrir las semillas. Cordo et al, (2007) establecieron que la técnica de recubrimiento de semillas es más efectiva contra la mancha foliar del trigo que la técnica de asperjado foliar. En el recubrimiento de semilla los propágulos de los agentes de biocontrol germinan en la superficie de esta y colonizan las raíces de las plántulas y la rizosfera rápidamente (Kumar et al, 2009).…”

“…Cepa de Trichoderma harzianum La cepa de Trichoderma harzianum Th5cc, se encuentra conservada en el Banco Micológico que funciona en Centro de Investigaciones de Fitopatología (CIDEFI-UNLP) perteneciente a la Facultad de Ciencias Agrarias y Forestales de la Universidad Nacional de La Plata (Stocco et al, 2011). Esta cepa fue aislada del filoplano de trigo y utilizada como antagonista de Zymoseptoria tritici por Cordo et al, (2007). Se identificó molecularmente siguiendo la técnica descripta por Stocco et al, (2016).y fue depositada en la base de datos del European Molecular Biology Laboratory (EMBL) bajo el número de accesión LN869401.…”

“…Además, algunas especies de este género poseen capacidad de bioestimulación de crecimiento en algunos cultivos (Howell, 2003). Experiencias en la evaluación de la efectividad del Trichoderma harzianum Rifai para el control de enfermedades fúngicas desarrollados en sistemas agrícolas en nuestro país, mostraron que la cepa Th5cc de T. harzianum, causó una disminución del 20% en la severidad y 95% de la cobertura picnidial de la mancha de la hoja en trigo causada por Zymoseptoria tritici (Cordo et al, 2007). Asimismo, estos autores, demostraron que la actividad proteolítica antifúngica, medida 12 días después de la siembra, aumenta en plantas cultivadas a partir de semillas recubiertas con este antagonista e inoculadas con Z. tritici, este aumento confiere resistencia a los cultivares susceptible.…”