Description of the demicyclic life cycle of Puccinia sherardiana in Sphaeralcea angustifolia in Mexico.

. During 2017-2019, leaves and stems with dark brown lesions containing hypophyllous telia surrounded by 17 chlorotic halos were collected from Sphaeralcea angustifolia plants located in Axapusco, State of Mexico. Based on 18 the morphological characteristics of pycnia, aecia and telia observed by light microscopy and scanning electron 19 microscopy, the fungus Puccinia sherardiana was identified. Uredial stage was not present during the observation 20 period. Identity verification was carried out by phylogenetic analysis with sequences of part of the 28S gene from 21 ribosomal DNA. In addition, pathogenicity tests were done on S. angustifolia leaves by inoculating teliospores. The 22 inoculated plants developed symptoms 15 days after inoculation, the signs beginning with the presence of aecia in 23 the epidermis of the host and later telia were formed, completing the Koch Postulates. Puccinia sherardiana was 24 previously described as a rust with a microcyclic life cycle on species of the genera Alcea, Malvastrum, Sidalcea and 25 Sphaeralcea , belonging to the Malvaceae family, however, this study revealed that this plant pathogenic fungus has a 26 demicyclic life cycle.


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The Sphaeralcea genus (Malvaceae) is represented by around 40 species that are found mainly in the 29 western part of North America, and more than 50% are distributed in Mexico. Some species are used in traditional 30 medicine, for example, the Navajo Indians use the leaves of S. coccinea to treat skin diseases ( grasslands, but mainly in arid areas. It is also found on roadsides, disturbed areas, abandoned cultivation fields, urban 39 areas and frequently as weeds along railroad tracks (Fryxell 1992

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The final alignment of the sequences was 695 sites, of which 129 were conserved, 551 variable but not informative,

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It is important to mention that in this work, the morphometric characteristics of the pycnia and pycniospores are

Conflicts of interest/Competing interests:
The authors declare that they have no conflict of interest.

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Availability of data and material (data transparency): All data generated or analysed during this study are 236 included in this article.

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Code availability (software application or custom code): Not applicable.