Pucciniales

Pucciniales is an order of rust fungi within the class Pucciniomycetes, in the phylum Basidiomycota and subphylum Pucciniomycotina. Formerly recognized as Uredinales, they are obligate biotrophic plant pathogens that cause rust diseases on a wide range of vascular plants, including many crops and ornamentals.

Rust fungi in this order are typically characterized by complex life cycles and specialized infection structures. Most species are dikaryotic during their asexual and most of their sexual phases and form haustoria that penetrate living plant cells to extract nutrients. Their spore production commonly involves a sequence of spore stages, often including pycnia (spermogonia) that produce spermatia, aecia that produce aeciospores, uredinia that produce urediniospores, and telia that produce teliospores; basidiospores are produced from teliospores. Many Pucciniales are heteroecious, requiring two different host species to complete their life cycle, while others are autoecious and complete all stages on a single host.

Ecologically, Pucciniales exhibit a broad host range at the level of plant groups, with significant species-level host specificity. They are widespread in temperate and tropical regions and include several economically important pathogens, such as Puccinia graminis, the stem rust of wheat, and numerous rusts affecting beans, coffee, and other crops. Their reliance on living hosts and often long, multihost life cycles can complicate disease management.

Taxonomically, Pucciniales comprises a large and diverse assortment of genera, including Puccinia, Uromyces, and Gymnosporangium. Understanding their life cycles and host interactions remains central to studying plant pathology and rust biology.