AGRICULTURAL SCIENCES DOI: 10.22616/rrd.25.2019.051 CHARACTERIZATION OF PUCCINIA RECONDITA, THE CAUSAL AGENT OF BROWN RUST: A REVIEW Kintija Peksa1,2, Biruta Bankina1 1Latvia University of Life Sciences and Technologies, Latvia 2Institute of Agricultural Resources and Economics, Latvia [email protected] Abstract Brown rust caused by Puccinia recondita is a significant disease in cereal growing areas worldwide. On average, brown rust can cause yield losses from 10% to 40% resulting in economic losses. The disease damages the leaves, stems and glumes of cereals. Classification of the pathogen causing brown rust has undergone several revisions. There are two different opinions about the causal agent causing brown rust on rye and wheat. Some scientists consider that the causal agent of brown rust in wheat (Triticum aestivum L.) and rye (Secale cereale) is included in the broad species of P. recondita defined by Cummins, but other scientists consider that there are two species causing brown rust – P. recondita in rye and P. triticina in wheat. There are many studies about the races of P. recondita in wheat: in North America, 70 races are collected every year; in Canada, 35 races have been found; in Europe, 105 races have been found. Unfortunately, there are no studies about the races of the pathogen of rye. P. recondita is a heteroecious fungus with a complicated life cycle. For successful development, the fungus requires cereals as primary hosts and different alternative hosts, depending on the specialization of the pathogen. Specific studies about the biology, distribution and harmfulness of Puccinia recondita in Latvia are necessary. Monographic method was used for this study. The aim of this article is to summarize the information from the literature about Puccinia recondita, the causal agent of brown rust, with emphasis on the occurrence, harmfulness, taxonomy, and life cycle of P. recondita f. sp. secalis. Key words: taxonomy, cereal, fungal diseases, rye, Uredinales. Introduction urediniospores on cereal hosts, and pycniospores and Brown rust (also called brown leaf rust) caused by aeciospores on the alternative hosts. Puccinia recondita (syn. Puccinia triticina) can infect Genetic resistance is most commonly used to wheat (Triticum aestivum L.), rye (Secale cereale), prevent yield losses caused by brown rust. The triticale (×Triticosecale), and barley (Hordeum identification of pathogens’ races is very important for vulgare). Brown rust is widespread in major wheat the breeding of resistant varieties (Bolton, Kolmer, & production regions such as America, Africa and Europe Garvin, 2008). (Ordonez, German, & Kolmer, 2010; Huerta-Espino There are many studies about the races of brown et al., 2011). Brown rust is the most widespread and rust in wheat, but no research has been carried out on prevalent disease of wheat in South America (German the races of P. recondita in rye. et al., 2007). In the USA, epidemics of brown rust on The aim of this article is to summarize the winter wheat have occurred in the southern part of the information from the literature about Puccinia country more frequently than in the areas in north of recondita, the causal agent of brown rust, with the country. Brown rust is the most important wheat emphasis on the occurrence, harmfulness, taxonomy, disease in Mexico (Roelfs, 1989). Level of yield and life cycle of P. recondita f. sp. secalis. losses caused by leaf rust are different, depending on various weather conditions, availability of inoculum Materials and Methods and cultivar susceptibility (Teferi, 2015). The disease Monographic method was used for this study. can cause yield losses in wheat from 5% to 10% in Scientific literature from different countries related to Canada, from 10% to 22% in the USA, and up to 40% Puccinia recondita (the causal agent of cereal brown in Mexico (Moschini & Perez, 1999). rust), its biology, evolution and distribution was Brown rust caused by Puccinia recondita f. sp. summarized. secalis occurs regularly in all areas where rye is growing. This disease is one of the most significant Results and Discussion diseases of rye in Europe (Miedaner et al., 2012), and Distribution and harmfulness of brown rust it is common also in Latvia (Bankina et al., 2013). Brown rust occurs on wheat (Triticum aestivum Early infection of brown rust in continental climates L.), rye (Secale cereale), triticale (×Triticosecale), can cause yield losses of up to 40%, and if the and barley (Hordeum vulgare). The occurrence of epidemic is early and strong – even up to 60 – 80% in brown rust is high in all regions where rye, wheat rye (Kobylanski & Solodukhina, 1996). and triticale are produced. Under Latvia’s climatic Puccinia recondita is a heteroecious fungus, conditions, brown rust in rye sowings appears every macrocyclic, and has five distinct stages of year, but wheat and triticale sowings are seldom development: teliospores, basidiospores, and infected (Treikale, 2010, 2016). 70 RESEARCH FOR RURAL DEVELOPMENT 2019, VOLUME 2 CHARACTERIZATION OF PUCCINIA RECONDITA, THE CAUSAL AGENT OF BROWN RUST: A REVIEW Kintija Peksa, Biruta Bankina Wheat brown rust can cause a reduced number 1885, it was considered that more than one species of kernels per head and kernel weight (Kolmer, can cause brown rust on various plants. Later, many 2013). Grain losses can reach up to 30 – 70% even species were described and named according to host in susceptible varieties in South America (Ordonez, specialization. The classification of causal agents of German, & Kolmer, 2010). Different results have been brown rust proceeded to be modified from time to obtained in Europe, where yield losses in susceptible time (Liu et al., 2013). cultivars reached 14 – 29%, mainly due to reductions In 1894 and 1899, Eriksson and Henning described in kernel weight (Huerta-Espino et al., 2011). Findings many species (P. agropyrina, P. bromina, P. dispersa, of American researchers confirm that yield losses P. glumarum, P. holcina, H. mollis, P. simplex, P. caused by rust can make 5 – 15% in Canada, 10 – 22% triseti, P. triticina), which before were grouped as one in the USA, 9 – 51% in Argentina, and even up to 40% species – Puccnia rubigo-vera. Arthur and Fromme, in Mexico (Moschini & Pérez, 1999). in contrast, united all forms of P. rubigo-vera with Brown rust in rye can cause significant yield losses, alternative host plants from Ranunculaceae family especially when infection is early. In continental into one species with one name – Dicaeoma clematidis. climates, yield losses can reach up to 40%, and if the Mains in 1933 suggested to place all featured species epidemic is early and strong – even up to 60 – 80% causing brown rust back into one species under name (Kobylanski & Soludhkina, 1996). Disease severity in Puccinia rubigo-vera. In 1934, Arthur accepted the Latvia in some years increased up to 15% (Treikale, causal agents of brown rust as one species P. rubigo- 2010, 2016). vera. Cummins and Caldwell in 1956 suggested Brown rust is a significant disease for winter Puccinia recondita as the valid binomial for the causal triticale in Poland, and the infections caused by P. agents of brown rust of grasses and cereals. This broad recondita can result in substantial yield losses (Wooe, species concept was widespread in North America Maekowiak, & Cichy, 1994). (Huerta-Espino et al., 2011). Harmfulness of brown rust depends on the time of P. recondita has alternative hosts in four infection – earlier appearance of disease leads to more families of plants (Balsaminaceae, Boraginaceae, substantial yield losses. Hydrophyllaceae, and Ranunculaceae). Cummins There are findings which confirm that brown in 1956 and Caldwell in 1971 placed all causal rust infection depends on the cultivar. In Finland, agents of brown rust into one species, because of rye cultivars differed in brown rust infection level; spore morphology and host range was similar. Other however, the effect of cultivar was also directly scientists arranged these pathogens into more than one related to the time and location of sowing (Serenius et species, because of small but permanent differences al., 2005). In Latvia, observations showed that disease in the morphology of teliospores, aeciospores and severity differed depending on the cultivar, but clear uredospores (Savile, 1984). There are two diverse regularities were not found (Bankina et al., 2013). opinions about the P. recondita complex: some of Characterisation of the pathogen researchers hold the opinion that the causal agent of Causal agents of brown rust belong to the genus brown rust in wheat and rye is included in the broad Puccinia, family Pucciniaceae, order Pucciniales, species of P. recondita, but some consider that there phylum Basidiomycota in the kingdom Fungi. are two species that cause brown rust – P. recondita in The classification of these pathogens has undergone rye and P. triticina in wheat. several revisions. The fungi develop on two different The causal agents of cereal brown rust have been hosts: uredospores, teliospores and basidiospores divided into various species including Puccinia develop on the principal host, and pycniospores aegilopis (Maire, 1914), Puccinia dispersa (Gaumann, and aeciaspores develop on the alternative host. At 1959), Puccinia persistens (Urban, 1992), P. rubigo- the beginning, the causal agent of brown rust was vera (Arthur, 1934), Puccinia tritici-duri (Viennot- designated as Uredo rubigo-vera in 1815 by Augustin Bourgin, 1941), and Puccina triticina (Savile, 1984), de Candolle. Winter in 1884 placed the causal agent of and P. recondita as well (Cummins, 1971). The causal this disease in the species complex of P. rubigo-vera. agent of brown rust in wheat and rye is included in the Eriksson in 1899 was the first one to report Puccinia broad species of P. recondita; however, some scientists triticina as a single species. At the beginning of the separated this pathogen into two species – P. recondita 20th century, it was adopted by many scientists in (rye group) and P. triticina (wheat group) (Savile, North America and Europe that some species infect 1984; Swertz, 1994) or P.