普通系コムギ由来の赤かび病抵抗性 QTL を導入したデュラムコムギ系統の評価

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  • Improving Fusarium head blight resistance by introducing the QTLs from bread wheat in durum wheat

抄録

デュラムコムギ(Triticum turgidum ssp. durum(Desf.)Husn. 2n=4x=28 AABB)は赤かび病に極めて弱く,開花期から成熟期に降雨による赤かび病の被害が拡大しやすいため,赤かび病抵抗性の向上が急務である.赤かび病は Fusarium graminearum Schwabe が小花に感染し,拡大する病斑を示すとともにデオキシニレバノール(DON)を始めとする人体に有害な毒素を蓄積することが知られている.本研究は 4 倍体のデュラムコムギに赤かび病抵抗性を付与することを目的にしているが,赤かび病抵抗性が強いデュラムコムギの報告は少ない.そのため赤かび病抵抗性普通系コムギ(T. aestivum L. 2n=6x=42 AABBDD)からA およびB ゲノムに由来する赤かび病抵抗性 QTL Qfhs.ndsu-3BS(3BS)および Qfhs. ifa-5A(5A)を戻し交配によりデュラムコムギに導入し,その効果を評価した.赤かび病抵抗性の検定は,BC3 系統およびBC5 の準同質遺伝子系統(NILs)を用い散水設備を設置したビニールハウス内で行い,出穂期に赤かび病菌を接種した大麦粒を散布し, 散水により赤かび病を誘発した.赤かび病抵抗性は 開花後 21・28 日目の罹病穂率,収穫した種子の整粒歩合,DON 蓄積量で評価した.3BS を導入したBC3 系統および NILs は罹病穂率が低下する傾向にあり,年次によっては整粒歩合の向上やDON 蓄積量の低下の傾向が見られ,赤かび病抵抗性が向上する傾向が明らかになった.3BS に加え 5A を導入したNIL は赤かび病抵抗性の更なる向上は認められなかったが,5A の抵抗性遺伝子領域が脱落した可能性があり,さらに詳細な赤かび病抵抗性の評価が必要である.Since durum wheat (Triticum turgidum L. ssp. durum (Desf.) Husn. 2n=4x=28 AABB) is susceptible to Fusarium head blight (FHB), improvement of FHB resistance is important. FHB is caused by Fusarium graminearum Schwabe. The pathogen infects spikelets. Spreads to rachis and other spikelets, inhibits seed maturation, and accumulate mycotoxins such as a deoxynivalenol (DON) in seeds. Strong FHB resistance in durum wheat is limited, but the resistance of bread wheat (T. aestivum L. 2n=6x=42 AABBDD) is well-known. The purpose of this study is to evaluate FHB resistance introduced from bread wheat into durum wheat. We developed the durum wheat lines with two resistant QTLs, Qfhs.ndsu-3BS (3BS) and Qfhs.ifa-5A (5A), from bread wheat by backcrossing. The BC3 and BC5 (near isogenic lines; NILs) lines were investigated FHB resistance in 2015, 2016 and 2017. Fusarium inoculation test was performed in a greenhouse equipped with a water sprinkle and fusarium infected barley grains as a spreader scattered. FHB resistance was evaluated by the ratio of fusarium infected spikes to total spikes, the ratio of sound grain weight to total grain weight and DON content. The ratio of infected spikes of lines with 3BS appeared to be less than that of recurrent parent. but the ratio of sound grain weight was not significantly different from that of the recurrent parent. The DON content of lines with 3BS was significantly lower than that of the recurrent parent in 2015, the lines with 3BS tended to improve it in 2016. Results were different from year to year. This difference might be due to differences in weather. Further improvement of FHB resistance was not observed in the NIL with both 3BS and 5A in a one-year test, that to need to confirm with more test.

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