| Scientific Name | Bremia elliptica Sawada, Bot. Mag. (Tokyo): (139) (1914) |
|---|---|
| Synonyms | - |
| Disease | Downy mildew |
| Taxonomic Rank | |||
|---|---|---|---|
| Order | Peronosporales | Family | Peronosporaceae |
| Host Plant | |||
|---|---|---|---|
| Common Name | Indian lettuce (왕고들빼기) | Scientific Name | Lactuca indica var. laciniata |
| Distribution | East Asia, including Taiwan, Japan, and Korea. |
|---|---|
| Characteristics | Lesions commonly present on leaves, causing discoloration of the affected tissues, initially pale green to yellow, later becoming brown to dark brown, polyangular, vein-limited, frequently covering larger areas by coalescing. Down present on the lower leaf surface, whitish, consisting of dense, felt-like conidiophore growth restricted by veins. Conidiophores (195–)196–225–254(–280) μm long; trunk 9–13 μm wide below the first branch; branching dichotomous or monopodial, with the first branch arising at 3/10–5/10 of the total height; 4–6 branching orders; callose plugs often present in the trunk and branches. Ultimate branchlets substraight to slightly curved, 9–24 μm long. Apical vesicles (n = 50) spherical, but often confluent, 8–13 μm diam., bearing 3–5(–6) extensions, 5–9 μm long; tips obtuse to somewhat swollen, 1.5–2 μm wide. Conidia (n = 100) subglobose to oblong, subhyaline to hyaline, (15.6–)16.5–17.6–18.7(–19.9) × (14.2–)15.7–16.7–17.7(–18.3) μm, with a length/width ratio of (0.99–)1.02–1.06–1.09(–1.13); pedicel absent or rarely represented by a short conical projection. |
| Notes | Bremia elliptica was originally described by Sawada (1914) from Lactuca indica in East Asia. For much of the twentieth century, most Bremia species infecting Asteraceae were broadly treated as B. lactucae and consequently records from Lactuca species were frequently assigned to B. lactucae. However, multilocus phylogenetic analyses combined with detailed morphological comparisons demonstrated substantial host-associated diversity within Bremia. In particular, isolates from L. indica formed a phylogenetically distinct lineage from B. lactucae occurring on L. sativa, supporting recognition of B. elliptica as a distinct species (Choi et al. 2011). Subsequent multilocus analyses of Bremia and their asteraceous hosts further supported the evolutionary distinctiveness and strong host association of B. elliptica (Choi and Thines 2015). In Korea, downy mildew on L. indica and related infraspecific taxa was recorded as B. lactucae by Shin and Choi (2003, 2006). However, Korean specimens collected from L. indica var. laciniata were subsequently included in multilocus phylogenetic and morphological analyses and identified as B. elliptica (Choi et al. 2011). |
| Economic importance | Bremia elliptica is primarily associated with wild Lactuca indica and is not known to cause major economic losses in cultivated crops. Its economic importance is therefore considerably lower than that of B. lactucae, which causes destructive downy mildew of cultivated lettuce (L. sativa). In Korea, B. elliptica occurs on wild populations of L. indica, where infection produces chlorotic to brown, vein-limited lesions and conspicuous whitish sporulation on the lower leaf surface. No significant agricultural or economic losses caused by B. elliptica have been documented in Korea. |
| References | Choi, Y. J., et al. 2011. Fungal Biol. 115:102. Choi, Y. J., and Thines, M. 2015. PLoS ONE 10:e0133655. Sawada, K. 1914. Bot. Mag. (Tokyo) 28:132. Shin, H. D., and Choi, Y. J. 2003. Mycotaxon 86:249. Shin, H. D., and Choi, Y. J. 2006. Peronosporaceae of Korea. National Institute of Agricultural Science and Technology, Suwon. |
