Hybrid rice based on heterosis can significantly increase rice yield compared to inbred rice. Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive bacterial diseases that affect hybrid rice production. To breed a broad-spectrum and high disease resistance to BB in hybrid rice, we introduced the Xa4, Xa21 and Xa27 genes into the restorer lines of Mianhui 725 or 9311 genetic backgrounds and pyramided the three R genes in the progeny derived from the cross between the two lines. A near-isogenic line of the Xa27 gene in the genetic background of 9311 [9311(Xa27)] and another line with the Xa4 and Xa21 genes in the genetic background of Mianhui 725 (WH421) were firstly developed through marker-assisted selection. A new restorer line carrying Xa4, Xa21 and Xa27, designated as XH2431, was selected from the F8 progeny of the cross between 9311(Xa27) and WH421 through marker-assisted breeding and pedigree selection. XH2431 and II You 2431, the hybrids derived from cytoplasmic male-sterile line II-32A and restorer line XH2431, conferred high resistance to all 23 Xoo strains collected from 10 countries. XH2431 restored the fertility of II-32A to the normal level in the F1 generation. In addition, II You 2431 showed good agronomic traits under greenhouse conditions. The development of XH2431, 9311(Xa27) and WH421 provides a set of restorer lines with broad-spectrum and enhanced resistance to BB for hybrid rice.
因雜種優(yōu)勢，雜交稻的產(chǎn)量比常規(guī)稻有顯著提高。白葉枯病菌引起的水稻白葉枯病是對雜交稻生產(chǎn)最具破壞性的細菌性病害之一。為了培育具有廣譜抗性的高抗白葉枯病雜交稻品種，我們將Xa4、Xa21和Xa27基因?qū)刖d恢725或9311為背景的恢復(fù)系并通過2個株系的雜交后代將3個R基因疊加。首先通過分子標記輔助選擇得到了以9311為背景帶有Xa27基因的近等基因系9311(Xa27)和另一個以綿恢725為背景帶有Xa4和Xa21基因的株系(WH421)。進一步利用分子標記輔助育種和系譜選擇從9311(Xa27)和WH421的雜交F8后代中構(gòu)建一個帶有Xa4、Xa21和Xa27的新恢復(fù)系（XH2431）。XH2431和Ⅱ優(yōu)2431（胞質(zhì)不育系Ⅱ-32A與恢復(fù)系XH2431產(chǎn)生的雜交后代）對來自10個國家的23個白葉枯病菌都具有高抗水平。XH2431與Ⅱ-32A的F1代恢復(fù)了正常育性。此外Ⅱ優(yōu)2431在溫室里農(nóng)藝性狀也表現(xiàn)較好。通過對XH2431、9311(Xa27)和WH421的培育，我們提供了一套具有廣譜白葉枯病抗性的雜交水稻恢復(fù)系。