A Global Overview of Diversity and Phylogeny of the Rust Genus Uromyces

Abstract

Uromyces is the second-largest plant pathogenic rust genus, is responsible for numerous diseases, and has major effects on both agricultural and non-agricultural plants. The genus is generally characterized by its unicellular teliospores that help to characterize it and distinguish it from another important rust genus, Puccinia. In this study, a global overview of the diversity and distribution of Uromyces is presented based on both online and offline resources. The information obtained was analyzed for numerical and graphical summaries to provide the diversity and distribution of the genus by country and continent. Besides this, broad taxonomical aspects, a brief life cycle, and other comparative aspects on diversity and distribution were also provided. In addition, a phylogenetic analysis based on the ITS and nLSU DNA sequence data available in GenBank and published literature was performed to examine the intergeneric relationships of Uromyces. The results obtained revealed that the rust genus is found distributed over 150 countries, territories, and occupancies of the world on around 647 plant genera belonging to 95 plant families. Phylogenetic studies based on LSU and ITS sequence data revealed that Uromyces species are polyphyletic and require more DNA-based analyses for a better understanding of their taxonomic placement.

Keywords: Pucciniomycotina; Uromyces; phylogeny; rust fungi; taxonomy.

Figure 1

Disease symptoms of species of Uromyces. (A,B) Uromyces ambiens on Buxus wallichiana; (C–E) Uromyces fabae on Pisum sativum; (F,G) Uromyces geranii on Geranium sp.; (H,I) Uromyces trifolii on Trifolium sp. Scale bar: A–I = 1 mm.

Figure 2

A general life cycle of rust genus Uromyces.

Figure 3

Phylogram generated from PAUP analysis of Uromyces species of ITS sequences. The scale bar indicates 70 changes and outgroup Gymnosporangium przewalskii BJFCR01859_NR154073. Bootstrap values of MP > 60% are given above branches, and 72 sequences are included in the phylogenetic analyses. The best maximum parsimony (MP) dataset consists of 394 total characters, of which 164 were constant, 156 parsimony-informative, and 74 parsimony-non-informative. The parsimony analysis of the data matrix showed a thousand equally parsimonious trees with a length of 917 steps in the first tree (CI = 0.408, RI = 0.702, RC = 0.286, HI = 0.592).

Figure 4

Phylogram generated from PAUP analysis of Uromyces species of LSU sequences. The scale bars indicate 60 changes and outgroup Gymnosporangium przewalskii BJFCR01859_NG060667. Bootstrap values of MP equal to or greater than 60% are given above branches, and 58 sequences are included in the phylogenetic analyses. The best maximum parsimony (MP) dataset consists of 873 total characters, of which 600 were constant, 125 parsimony-informative, and 148 parsimony-non-informative. The parsimony analysis of the data matrix showed 1000 equally parsimonious trees with a length of 625 steps in the first tree (CI = 0.550, RI = 0.708, RC = 0.389, HI = 0.450).

Figure 5

Heat map to show the global distribution and species richness of Uromyces spp.

Figure 6

Heat maps to show the continental distribution and species richness of Uromyces spp.

Figure 7

Family-wise comparison of genera of infected host plants.

Figure 8

Occurrence of Uromyces species with some host plants. (A–G) Uromyces fabae on Pisum sativum (pea). (A) Aecia; (B,C) Uredia; (D) Telia; (E) Aeciospores; (F) Urediospores; (G) Teliospores; (H–J) Uromyces geranii on Geranium sp.; (H,I) Uredia; (J) Uredinospores; (K–N) Uromyces rumicis on Rumex sp; (K,L) Uredia; (M) Urediospores; (N) Teliospores; (O–R) Uromycesviciae-fabae on Vicia faba; (O–Q) Different rust sorus on natural host; (R) Aecia; (S) Urediospores and Teliospores; (T–W) Uromyces trifolii on Trifolium sp.; (T–V) Uredia and Telia; (W) Teliospores. Scale bars: C,I,L,Q,R,U,V = 1 mm; D = 0.5 mm; E,F,G,J,M,N,S,W = 20 µm.

Figure 9

Geographical heat map showing distribution of endemic/native Uromyces species.