Effect of bunt infection on the frost resistance of wheat varieties and of lines containing Bt genes

Abstract

AbstractIn artificial infection experiments carried out in the nursery in Martonvásár in 1991, 1992 and 1993, studies were made on the bunt infection of wheat varieties bred in Martonvásár and of monogenic lines containing known resistance genes (Bll to Btl0, respectively). This was followed in 1993 by tests on the frost resistance of healthy wheat seedlings and wheat seedlings artificially infected with bunt in the frost‐testing chamber of the Martonvásár phytotron.During the period of the experiment, the local pathogen population was avirulent to genes Bt9 and Btl0, and virulent to Bt7. Monogeniclines containing resistance genes Bt4, Bt5, Bt6 and Bt8 had good resistance, while that of lines containing Bt1, Bt2 and Bt3 was only moderate. Among the cultivated varieties, only three proved to be moderately resistant (Martonvásári 17′,‘Martonvásári 23′,‘Fatima 2′), while the remainder were susceptible or very susceptible. The frost resistance of plants infected with bunt was significantly lower, over an average of the varieties, than that of healthy plants. A close (r = 0.890) correlation was found between the bunt susceptibility of the varieties tested and the increase in frost kill due to infection, while no correlation was observed in this respect for monogenic lines containing various resistance genes (Bt).