Treatment with chitosan protects habanero pepper against the infection with phytophthora capsici

Israel Journal of Plant Sciences

DOI: 10.1560/IJPS.58.1.61

Vol. 58

2010

pp. 61–65

Treatment with chitosan protects habanero pepper against the infection with Phytophthora capsici
Héctor Mukul lópez,a elizabetH ortíz Vázquez,b José Juan zúñiga aguilar,c and gabriel lizaMa uca,b,d,* Instituto Tecnológico del Sur del Estado de Yucatán, Carretera Muna-Felipe Carrillo Puerto, tramoOxkutzcabAkil, Km 41+400, Oxkutzcab 97880, Yucatán, México b Instituto Tecnológico de Mérida, Av. Tecnológico km. 5, Mérida 97118, Yucatán, México c Centro de Investigación Científica de Yucatán, Calle 43 No. 130, colonia Chuburná de Hidalgo, Mérida 97200, Yucatán, México d Unidad Multidisciplinaria de Docencia e Investigación, Facultad de Ciencias, Universidad Nacional Autónoma de México, Puertode abrigo s/n, Sisal 97355, Yucatán, México
a

(Received 6 September 2009; accepted in revised form 28 December 2009)

ABSTRACT Similar to most members of the genus Capsicum, the habanero pepper (Capsicum chinense Jacq.) is susceptible to the deadly disease Phytophthora blight caused by the oomycete Phytophthora capsici. Currently, this pathogen is controlled mainly with agrochemicals, anon-effective strategy with undesirable effects on the environment and human health. In this work, we evaluated the protective effect of chitosan against the infection with P. capsici. Cultivation of P. capsici in vitro in the presence of 10 µg ⋅ mL–1 chitosan reduced its growth significantly; however, higher concentrations (100 and 500 µg ⋅ mL–1) practically blocked its growth (by 90 and 95%,respectively). On the other hand, spraying high concentrations of chitosan (100 and 500 µg ⋅ mL–1) on three-month-old habanero pepper plants prevented the spreading of the oomycete, but lower concentrations (1 and 10 µg ⋅ mL–1) did not prevent the disease. Interestingly, the application of chitosan did not protect the plants if they were previously wounded; thus, it is possible that the treatment has adirect effect on the oomycte, instead of producing a defense-related response in the plant. Since chitosan is an innocuous food additive, our results suggest it can be used as an environmentally friendly complement to the traditional agronomical practices in the control of Phytophthora blight in peppers. Keywords: Phytphthora blight, plant disease, Capsicum, environmentally safe

INTRODUCTIONPeppers, belonging to the genus Capsicum, are native plants from Mesoamerica and South America. In 2007, Mexico was second in world pepper production, with 1,690,000 ton of fresh fruit; however, it was 39th in yields, with 18.17 ton/ha (FAOSTAT, 2007). This can be explained by deficiencies in agricultural practices, as well as by the negative impact of the diseases caused by pathogenicmicroorganisms. The habanero pepper

(Capsicum chinense Jacq.) is one of the pepper species cultivated in Mexico. It is becoming a promising crop because the local and foreign markets demand its high content of capsaicin. Phytphthora blight, caused by the oomycete Phytophthota capsici, is a devastating disease in peppers (Ristaino and Johnston, 1999). In spite of having been
*Author to whom correspondenceshould be addressed. E-mail: lizama73@hotmail.com

© 2010 Science From Israel / LPPLtd., Jerusalem

62 described almost a century ago (Leonian, 1922), at present there are no resistant species in the genus Capsicum with commercial value (Oelke et al., 2003). The disease has been controlled by rotation of culture and control of irrigation, as well as by the use of synthetic fungicides (Kuhajeket al., 2003). The use of pesticides represents more than 25% of the production costs of the habanero pepper (Caamal Cauich et al., 2004), and most of the pesticides have adverse effects on the environment. In this sense, environmentally friendly alternatives to combat P. capsici are still needed. Chitosan, a compound which is non-toxic to the plants, can induce or increase resistance against...