abstract
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Wheat (Triticum aestivum) serves as an important staple food for the Brazilian population, which consumes about 12 million tonnes of the grain each year. Less than half of this demand is met by national production, partly because of international commercial agreements, a geographic concentration of the production in the South and a poor transportation infrastructure. However, a major factor acting to discourage wheat production continues to be susceptibility to Fusarium Head Blight (FHB). It can cause direct losses in yield and industrial quality, plus contaminate products with mycotoxins such as deoxynivalenol (DON). Epidemic years occur frequently since the flowering stage usually coincides with warm and wet weather conditions. This makes both genetic resistance and a precise chemical control a necessity to satisfy the new Brazilian legislation on mycotoxin levels, which took effect in 2019. In the past, progress in breeding for more resistant cultivars was solely focused on field evaluations under natural disease pressure. This allowed the successful exploration of native sources such as cultivar ‘Frontana’ (mainly type I resistance), as well as Chinese and Mexican sources like ‘NyuBai’, ‘Nabeokabozu’ and ‘Sha/Catbird’. Over the last years, a backcross population involving ‘Sumai#3’ and the Brazilian cultivar ‘Alvorada’ was developed to pyramidize known genes and QTLs from both sources: Fhb1, Fhb5, QTL’7A and QTL'5A. The combination of these factors was associated with a significant decrease in DON content relative to ‘Alvorada’ in three locations in 2014; similar to resistant check ‘Sumai#3’. However, in Southern Brazil there are a myriad of important traits that need to be addressed before releasing a cultivar. Presently, our program aims at combining field and greenhouse plant evaluations with visual scoring of fusarium damaged kernels (FDK) and marker assisted selection (MAS), exploring new and standard resistance sources from Brazil, USA and China. This allows for increased efficiency of selection for FHB resistance (types I and II) and other desirable traits such as grain yield and industrial quality. The year of 2018 presented unusually strong FHB pressure under field conditions and was useful to validate this breeding method. Some of our next releases were selected under such conditions and display excellent FHB resistance combined with high yield potential, test weight and tan spot resistance, plus desirable rheological properties and bread-making quality. Products like these can strengthen the whole Brazilian wheat production chain and decrease the country’s dependence on foreign wheat.