In vitro evaluation of oat resistance to root rot: experience of application in breeding

As part of the selection process in the second year of the competitive variety trial, the resistance to Fusarium poae root rot toxins of the promising breeding lines of spring hasky oats (B-5, B-21, B-22, B-45, B-70) under callus culture conditions was assessed. Induction of callusogenesis of immature embryos at the stage of milky-wax ripeness was carried out by adding 2,4-D (3 mg/l) to Murashige and Skoog medium (MS). The developed calli were than cultivated on proliferation media (MS + 1.5 mg/l 2,4-D) containing 30% and 50% F. poae culture filtrate (CLF), as well as on the control one. Lines B-5 and B-70, as well as the standard variety Tubinsky, did not reduce their proliferative activity in the presence of CLF in comparison with the control medium (60-70%). There was also no decrease in the frequency of stem regeneration in callus culture of these genotypes. In the B-70 line, the frequency of callus necrosis was at the control level (15%) even at a CLF concentration of 50%. When ranking by a set of calli growth parameters, line B-70 had the maximum sum of ranks. The lines that were identified as outstanding by the results of a comprehensive assessment in vitro also exceeded the standard Tubinsky variety according to field tests in 2022, as before in 2021, in terms of 1000-grain weight: 39.3 g and 39. 7 g, respectively, versus 35.6 g for the Tubinsky variety. Visual assessment of the 12-day-old seedlings of the Tubinsky variety and line B-70 in growing vessels with soil inoculated with a suspension of F.poae spores showed the absence of visible traces of damage to the root zone and coleoptile. However, a decrease in the maximum quantum yield of photosystem 2 was recorded for the Tubinsky variety from 0.804 [0.798/0.809] to 0.794 [0.790/0.802], but not for the B-70 line, confirming the results of the in vitro assessment. Based on the totality of tests carried out, the B-70 line was classified as valuable.