Triticale Diseases - a Review

Abstract

Triticale in some early research concepts was doomed to serve as a bridge to transfer resistance to leaf diseases from rye into wheat. Over the recent several decades, owing to a hard, inventive and consistent work of researchers and breeders it has become one of more important cereal crops in several countries around the world. In addition to triticale commercial and agronomical values it still is and it will continue to be bridging transfers of resistance genes to various pathogens and pests mainly from rye to wheat. On the other hand, triticale is a crop on which meet pathogens of wheat and rye. In the latter respect triticale is also a bridge facilitating a direct contact between the pathogens, e.g. between physiological forms of the most important cereal rusts. Such contacts stimulate somatic hybridization and may finally result in new hybrid pathotypes carrying virulence genes (factors) to all three hosts, i.e. triticale, wheat and rye. In addition to the above, passaging of wheat or rye physiological forms of pathogens through the hybrid triticale tissue may adapt them to cross infections of triticale progenitors. Although still scarce, there is some evidence illustrating the above facts and it is to be discussed in the paper. Triticale over a long time has been considered as resistant to diseases. Although, this opinion is no longer true, in comparison to wheat and rye it still looks as a healthy crop. The first triticale disease which occurred in epidemic proportions was stem rust (Pucinia graminis f. sp. tritici) in Australia. Leaf and stripe rusts (P. recondita f. sp. tritici and P. striiformis) are also gaining in importance everywhere triticale is grown. The same concerns several facultative pathogens, such as the most damaging to triticale Septoria nodorum, Fusarium spp., Bipolaris sorokiniana, Pseudocercosporella herpotrichoides, and Gaeumannomyces graminis. Triticale diseases are being controlled by various means. One of such highly recommended means is to increase genetic diversity for resistance in triticale germplasm. This could be achieved through conventional and inconventional breeding methods, e.g. use of somatic embryogenesis and genetic engineering. In the paper those methods will be discussed and examples given.