【摘要】 【目的】研究抗病基因在水稻种群中的分布特征是培育抗病品种的基础。【方法】以水稻第9染色体上与Pi3/Pi5/Pii/Pi15等位的抗病位点LABR₆4为研究对象,结合稻瘟病抗性鉴定,对该位点中包含的两个抗病基因LABR₆4-1和LABR₆4-2在水稻群体中的分布特征进行了研究,并对其在单子叶植物中对应的直系同源序列进行了共线性分析。【结果】LABR₆4位点在水稻中存在的频率约为16%,所有存在该位点的粳稻均表现高抗病性,缺失该位点的粳稻品种均表现出高感病性,而籼稻品种中LABR₆4位点存在频率低于5%,虽然其存在情况下均表现出抗病性,但大部分缺失该位点品种也表现出抗性;存在LABR₆4位点的品种中,LABR₆4-2基因编码序列高度保守;LABR₆4起源于单子叶与双子叶植物完全分离后及单子叶植物分化早期,其在不同的单子叶植物的分化过程中一直保持着良好的共线性。【结论】粳稻抗稻瘟病表型与LABR₆4-1和LABR₆4-2存在与否紧密关联,而籼稻的相关性不大,表明籼稻中其他抗性基因在稻瘟病抗性过程中起主导作用;鉴于LABR₆4-2的高度保守性,可根据其编码序列设计分子标记,用于高效筛选抗稻瘟病粳稻品种;LABR₆4可能在不同单子叶植物抗病过程中均具有重要作用。更多还原

【Abstract】 【Objective】 A better understanding of the origin and distribution of disease resistance genes in rice germplasm is useful for breeding highly resistant varieties.【Method】We analyzed sequence diversity of the rice blast resistance locus LABR₆4, which contains two homologous genes, LABR₆4-1 and LABR₆4-2, is located in the allelic region of Pi3/Pi5/Pii/Pi15 on rice chromosome 9. In addition, we analyzed the microsynteny of the LABR₆4 orthologous region in different monocotyledons.【Result】The presence frequency（PF） of LABR₆4 is 16%. All of the japonica rice cultivars carrying LABR₆4 are highly resistant to rice blast and all of those without the locus are susceptible. In addition, the PF of LABR₆4 in the indica subpopulation is lower than 5%. Although LABR₆4 is correlated with the resistance to rice blast, many indica rice cultivars without LABR₆4 are also resistant to rice blast. We also found that the LABR₆4-2 sequence is much conserved. Moreover, the microsynteny analysis of the LABR₆4 orthologous region in different monocotyledons indicated that LABR₆4 originates after the separation of the monocotyledonous and dicotyledonous species, and at the early differentiation stage of monocotyledons.【Conclusion】The rice blast resistance phenotypes are closely correlated with the presence of the LABR₆4 locus in japonicasubpopulation, but not in indica, indicating that there are many other resistance loci in the indica subpopulation. The LABR₆4-2 sequence can be used for developing molecular markers in marker-assisted rice blast resistance breeding. It also indicated that LABR₆4 may play a role in disease resistance in different monocotyledons.更多还原