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Puccinia horiana Hennings, the causal agent of chrysanthemum white rust, is a worldwide quarantine organism and one of the most important fungal pathogens of Chrysanthemum × morifolium cultivars, which are used for cut flowers and as potted plants in commercial production regions of the world. It was previously reported to be controlled by Lecanicillium lecanii, Cladosporium sphaerospermum, C. uredinicola and Aphanocladium album, due to their antagonistic and hyperparasitic effects. We report novel antagonist species on Puccinia horiana. Fungi isolated from rust pustules in a commercial greenhouse from Villa Guerrero, México, were identified as Cladosporium cladosporioides and Cladosporium pseudocladosporioides based upon molecular analysis and morphological characters. The antagonism of C. cladosporioides and C. pseudocladosporioides on chrysanthemum white rust was studied using light and electron microscopy in vitro at the host/parasite interface. Cladosporium cladosporioides and C. pseudocladosporioides grew towards the white rust teliospores and colonized the sporogenous cells, but no direct penetration of teliospores was observed; however, the structure and cytoplasm of teliospores were altered. The two Cladosporium spp. were able to grow on media containing laminarin, but not when chitin was used as the sole carbon source; these results suggest that they are able to produce glucanases. Results from the study indicate that both Cladosporium species had potential as biological control agents of chrysanthemum white rust.

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The volatile fractions from the bark of eight species of Mexican Bursera were obtained using steam distillation and were subjected to tandem GC-MS analysis for identification of the main constituents. The most abundant components of steam volatiles were monoterpenoids from which alpha-terpineol, terpinen-4-ol, alpha-thujene, linalool and limonene were most frequently isolated. A series of sesquiterpenes and long-chain hydrocarbons were isolated and identified from the barks of some of the studied species . Some volatiles were assayed for anti-inflammatory activity using the TPA-induced ear edema bioassay in mice. The volatile fraction from Bursera lancifolia was about half as active as indomethacin.

IntroductionThe inflorescences of Tilia americana var. mexicana are used as an infusion in Mexican traditional medicine due to their tranquilizing effects; however, pharmacological and phytochemical studies of the leaves are lacking.