水稻抗白葉枯病新基因Xa23抗譜廣、抗性強(qiáng),被定位在第11染色體上。以攜帶抗白葉枯病基因Xa23的抗病品系CBB23為抗源,以優(yōu)良雜交稻親本9311和1826為受體材料,采用雜交和復(fù)交,在分離群體中利用與Xa23緊密連鎖的EST標(biāo)記C189進(jìn)行分子標(biāo)記輔助選擇,通過苗期分子標(biāo)記檢測和成株期農(nóng)藝性狀選擇,獲得160份目標(biāo)基因純合且農(nóng)藝性狀穩(wěn)定的株系。使用鑒別菌系P6,采用人工剪葉接種法,在苗期和孕穗期對21份重點(diǎn)株系進(jìn)行了抗性鑒定,所有株系在苗期和孕穗期都表現(xiàn)抗病。同時對3個不育系與其中5個株系配制的15個雜交組合進(jìn)行了抗性鑒定,所有組合在苗期表現(xiàn)抗或中抗,在孕穗期表現(xiàn)抗。對其中6個雜交組合進(jìn)行了品比試驗,2個組合產(chǎn)量略低于對照兩優(yōu)培九,其余4個組合的產(chǎn)量均高于兩優(yōu)培九,用于測配的3個株系C6201、C6271和C6351有望作為雜交稻恢復(fù)系在生產(chǎn)中應(yīng)用。研究表明在育種進(jìn)程中利用與Xa23基因緊密連鎖的分子標(biāo)記C189開展抗白葉枯病分子標(biāo)記輔助育種是一種有效的途徑。
The bacterial blight ( BB) of rice is caused by the pathogen Xanthomonas oryzae pv1 oryzae ( Xoo)1 BB is oneof the most important rice diseases all over the world1 The most effect ive and economical approach for BB control in riceproduction is using BB- resistant cultivars1 The broad- spectrum BB resistance gene Xa23 was originally identified from wildrice species Oryza ruf ipogon1 Xa23 was introduced into cult ivated rice variety JG30 by cross and continuous back- crosses,which resulted in the near- isogenic line CBB231 In our previous studies, Xa23 was mapped on the long arm of ricechromosome 111 In this study, we used CBB23 as Xa23 donor and the elite but BB susceptible restorer lines 9311 and1826 as recipients to develop BB-resistant restorer lines of hybrid rice1 The Xa23- linked EST marker C189 was used toselect Xa23 in the segregating populations1 Marker-assisted selection (MAS) for Xa23 was performed at the seedling stageof plants and followed by conventional selection for agronomic traits at the adult stage1 More than 160 introgression lines thatharbored homozygous Xa23 and showed stable agronomic traits were obtained1 Twenty- one of the introgression lines weresubject to BB disease inoculation at the seedling and booting stages in green house, and results showed that all the testedlines were resistant to the most destruct ive Xoo strain PXO99( P6) while the recipient parents 9311 and 1826 were highlysusceptible at both stages1 In addition, we used 5 of the introgression lines as restorer lines to make hybrids by crossing them with 3 sterile lines Pei. ai 64S, Guangzhan 63S and Yuetai A1 BB- inoculation tests showed the 15 hybrids wereresistant or moderately resistant to PXO99 at the seedling stage and highly resistant at the booting stage1 Field trials of 6selected hybrids showed that yields of the hybrids were equal to or even higher than that of the control super hybrid riceLiangyou Peijiu1 The lines C6201, C6271 and C6351 obtained in this study are hopeful of being restorer lines of hybrid ricewith great potential for commercialization in the near future1 These results clearly suggested that the Xa23-linked markerC189 could be effectively utilized in the BB- resistance breeding programs.