Reaction of wheat cultivars and differential lines to Puccinia triticina races in detached leaves

Abstract

353Leaf rust caused by Puccinia triticina (Pt) Eriks. is one of the major leaf diseases affecting wheat in Brazil. Damage caused to wheat by leaf rust can be assessed by using the normalized function Y = 1,000 -6.4 I (Y = yield kg/ha and I = leaf incidence) (16).The main strategies for leaf rust control have been the development and the cultivation of genetically resistant cultivars, as well as the application of fungicides to aboveground plant parts (16). Genetic resistance of wheat to Pt is not durable due to the high fungal variability, resulting in occurrence of at least one new virulent race at every wheat growing season (3).Resistant cultivars are developed by inoculating Pt in new lines of wheat. For wheat leaf rust, resistance is race-specific; thus, dominant races are individually inoculated into the material to be selected (3). This requires a lot of material, facilities to grow the plants, and facilities to maintain the pure races. Each Pt race should be maintained, multiplied and kept pure, preventing mixtures with other races. RESUMOPalavras-chave adicionais: Ferrugem da folha, raças fisiológicas, Triticum aestivum.O método de preservação de folhas de trigo destacadas , em placa de Petri, foi usado para inoculação e desenvolvimento do fungo Puccinia triticina, agente causal da ferrugem da folha do trigo. Foram comparadas as reações de 26 cultivares de trigo em plântulas cultivadas em vasos (in vivo) e em folhas destacadas (in vitro) inoculadas com quatro raças fisiológicas do patógeno. Inoculou-se também Turra, C.; Reis, E.M.; Barcellos, A.L. Reação de cultivares de trigo e de linhagens da série diferencial à raças de Puccinia triticina, em folhas destacadas. Summa Phytopathologica, v.40, n.4, p.353-357, 2014. 24 linhas da série diferenciadora de raças do fungo nas mesmas condições. Após a inoculação, o material foi mantido em câmara climatizada por 15 dias. A avaliação da reação foi realizada no 15º dia após a inoculação. Os resultados obtidos para cada raça nos genótipos avaliados confirmaram a eficiência do método de folha destacada na avaliação da reação de cultivares de trigo. Reaction of wheat cultivars and differential lines to Puccinia triticina races in detached leaves 10.1590/0100-5405/1993The technique of detached leaves can be an important tool to rationalize the evaluation of the reaction of cultivars in the determination of Pt races.This technique has been used in studies of host-pathogen interaction with obligate parasites, such as fungi that cause rusts. Grass leaves or leaf pieces (wheat, oats, barley, rice and others) have been allowed to float on water or sucrose-based solutions, with or without benzimidazole, cytokine or kinetin (4, 7,10,11,12,17,18).Mignucci (14), Felsenstein (8) and Felsenstein (9) mention that adaptation of the detached leaf method was implemented to monitor the sensitivity of Pt to different fungicides in Europe.Considering Pt new races, race determination in every season and resistance break in some cultivars, the search for new resistant cultivars requi...

Evaluation of leaf rust resistance and characteristics of Korean wheats

“…However, most Lr genes are not effective in conferring resistance to current races of leaf rust. Moreover, leaf rust has variable virulence and readily overcomes resistance through mutation [4]. Accordingly, new sources of resistance to leaf rust must be continually created and deployed.…”