Evaluation of the wheat promising lines response to Xanthomonas campestris pv. undulosa the causal agent of bacterial leaf streak of cereal in three provinces of Iran

Bacterial leaf streak of the cereal is one of the most important diseases of wheat and barley which was reported from Iran in 1989. The severity of this disease has increased since 2016 in some of the irrigated wheat fields of Iran. Using the resistant cultivars is the best way to manage this disease. In the past, the response of some elite lines and cultivars to this disease was studied and determined. As a result, it's critical to investigate how new promising lines respond to this illness. Under this context, the reaction of a variety of elite wheat lines and cultivars to this disease was examined in greenhouse settings in a recent research. In this study, the reaction of a number of wheat lines to this disease was evaluated in field conditions in three regions with different climates.

Seventy-one advanced lines received from the Seed and Plant Improvement Institute, were planted in the experimental farms of research stations in three provinces, including Hamadan, Lorestan, and Jiroft.  Each line was planted in two one-meter rows in a randomized complete block design in three repetitions. They were then sprayed with bacterial suspension (regional isolates) at a concentration of 108 cfu / ml by spraying at three times (during tillering, after stem elongation and at the beginning of heading/flowering). The percentage of leaf surface infection was recorded and evaluated fifteen days after the last inoculation. Data were analyzed using SAS software, and the means were compared using Duncan test at a 1% probability level.

The response of various lines to this bacterium was different in three regions. But, in general, the studied lines due to the reaction to this disease were evaluated susceptible (such as S-92-19, ICSBWEYT-17-3, N-91-17, ICSBWEYT-17-2, ICSBWEYT-17-9 and ICSBWEYT-17-7), Semi-sensitive (such as ICSBWEYT-17-11, ICSBWEYT-17-10, ICSBWEYT-17-16, ICSBWEYT-17-1 and ICSBWEYT-17-24) and tolerant (such as: C-91-4, N-91 -8, N-92-9 and CD-94-9).

The grouping of the lines' susceptibility to this disease in six specific groups has high overall coordination and fit with each other, in three areas. However, the infection severity of wheat lines with this disease significantly varied in different regions. Therefore, the severity of wheat line infection in Boroujerd was higher than in the other two areas. On the other hand, some lines in various regions had different reactions to the disease. For example, MS-92-18 line had relatively good tolerance in Boroujerd region, but not in Hamadan and Jiroft regions. Climatic and geographical conditions can affect the behavior of wheat genotypes to the disease and change their response in different climates. Many other researchers have proved this. The results of this study showed that although most of the studied wheat lines are susceptible to this disease, but there are also lines among them, that have good relative resistance which can be used as resistance sources in wheat breeding programs.