Biological studies of Puccinia lantanae, a potential biocontrol agent of “Lippia” (Phyla nodiflora var. minor)

Abstract

Phyla nodiflora var. minor (syn. P. canescens (Kunth) Greene) known as “lippia” is an invasive weed with considerable impact on agricultural systems and conservation areas in Australia. The rust fungus Puccinia lantanae Farl. has been proposed as a potential biocontrol agent of Lantana camara. As it was previously found in Lippia s.l. in Argentina, we aim to study: (i) its geographical distribution in Argentina, Bolivia, and Chile; (ii) teliospore germination and basidiospore formation under different incubation temperatures; (iii) the effect of teliospore age on germination capacity; (iv) the effect of heat shock on teliospore germination and basidiospore formation; and (v) the pathogenicity of the rust fungus on P. nodiflora. Field surveys were conducted in Argentina, Bolivia, and Chile. In vitro experimental assays of germination and pathogenicity were performed. The rust was found in four provinces of Argentina (Jujuy, Salta, Formosa, and Entre Rios) and was not found in Bolivia and Chile. Puccinia lantanae showed the maximum values of teliospore germination and basidiospore formation at 20°C. The effect of aging and heat shock treatments significantly reduced teliospore germination. Pathogenicity tests showed that P. nodiflora var. minor, reptans, and nodiflora were infected with the “Formosa” isolate. The isolates “Salta” and “Entre Rios” infected var. minor and reptans, being potential candidates for biocontrol.