AUTHOR=Ma Xinyao , Liu Yao , Li Qiao , Tian Xiaxia , Du Zhimin , Kang Zhensheng , Zhao Jie 

TITLE=Identification of Berberis spp. as Alternate Hosts for Puccinia achnatheri-sibirici Under Controlled Conditions and Morphologic Observations of Sexual Stage Development of the Rust Fungus

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01278

DOI=10.3389/fmicb.2020.01278

ISSN=1664-302X

ABSTRACT=<p>Gramineous grasses are a large group of species, many of which act as accessory (secondary) host for a large number of rust fungi, including devastating rust pathogens of cereals. Among the rust fungi, some are known to be heteroecious and have a complete macrocyclic life cycle with five types of spores on distinct plant species, but for many others the complete life cycle is unknown. <italic>Puccinia achnatheri-sibirici</italic>, a rust fungus infecting grasses in the genus <italic>Achnatherum</italic>, has been known for only its uredinial and telial stages; however, the other (pycnial and aecial) stages have not been identified. In this study, we demonstrate that <italic>P. achnatheri-sibirici</italic> is a heteroecious, macrocyclic fungus with the sexual stage on barberry (<italic>Berberis</italic> spp.) through inoculation. Pycnia and aecia were successively produced on the inoculated barberry plants. Inoculation of <italic>Achnatherum extremiorientale</italic> leaves with aeciospores produced yellow-orange uredinia with high infection types, whereas inoculation of wheat variety Mingxian 169, highly susceptible to <italic>Puccinia striiformis</italic> f. sp. <italic>tritici</italic> which causes stripe rust on wheat, produced chlorotic flecks but no uredinia. The ITS sequence analysis of <italic>P. achnatheri-sibirici</italic> did not match with any sequence in the NCBI database and had the highest homology with 94% compared to <italic>Puccinia brachypodii</italic> and <italic>Puccinia aizazii</italic>. Observations of the uredinial, telial, and basidial stages on <italic>A. extremiorientale</italic> and pycnial and aecial stages on <italic>Berberis shensiana</italic> using light and scanning electron microscopes revealed its characteristics. Morphological characteristics of urediniospores and teliospores are most similar with those of <italic>P. achnatheri-sibirici</italic> described in the literature. This study proved (1) the life cycle of <italic>P. achnatheri-sibirici</italic> as heteroecious and macrocyclic and the alternate host as barberry; (2) the description of life stages in the sexual cycle, especially the morphologies of aecial, pycnial, and basidial stages; and (3) the expansion of knowledge on the rust flora on barberry.</p>