利用MAS技术培育水稻多抗、优质强恢复系桂恢663

【目的】培育新的兼抗稻瘟病、白叶枯病和细菌性条斑病,且米质较优的水稻强恢复系,为选育抗病、高产、优质的杂交稻组合提供良好的亲本材料。【方法】以抗稻瘟病品种合丰占为母本,与抗白叶枯病品系粤泰占杂交,通过分子标记辅助选择(MAS),获得多个抗病基因聚合的优良单株,再经过多代自交选育,并进行田间抗性及米质鉴定、农艺性状考察及恢复力测试。【结果】培育出聚合了抗稻瘟病基因Pi-ta、Pib、Pi54和抗白叶枯病兼抗细条病基因xa5的多抗、优质强恢复系桂恢663。桂恢663对白叶枯Ⅳ型菌和强毒Ⅴ型菌表现为抗,对广西细条病优势菌株JZ-8表现为抗,对14个稻瘟病菌株,有12个达到1级抗性。桂恢663除直链淀粉含量偏低外,其余6个主要米质指标均达到国标2级标准,其与丰田1A所配抗病、高产、优质组合丰田优663通过广西品种审定。桂恢663和丰田优663谷粒具有香味。【结论】桂恢663兼抗稻瘟病、白叶枯病和细条病,且恢复力强、米质较优具有香味,是组配抗病、高产、优质杂交组合的优良亲本,同时为水稻提供重要遗传基础材料。

兼抗白叶枯病和细条病水稻材料的创新及育种利用

【目的】探讨抗白叶枯病兼抗细条病基因在杂交稻抗性改良利用中的可行性,为丰富我国水稻育种遗传基础提供参考依据。【方法】利用分子标记方法对102份水稻品种资源(材料)进行抗白叶枯病兼抗细条病xa5基因筛选。以携带xa5基因且对白叶枯病和细条病具有良好兼抗性的亲本为抗源,与感病栽培稻杂交,通过系谱法,结合分子标记辅助选择,培育优良杂交稻恢复系。优良恢复系与不育系组配出强优势组合,分析强优势组合的抗性和综合农艺性状。【结果】从102份水稻品种资源(材料)中筛选出兼抗白叶枯病和细条病xa5基因的稻种资源17份,经抗性鉴定,DP3、IRBB5、N36、N776、N777、N779和P89对白叶枯病和细条病均表现较好的兼抗性。以广恢998为母本、以DP3与9311的杂交后代优良单株Y240-1为父本进行杂交,结合分子标记辅助选择,经多代自交选育,培育出含xa5基因的优良恢复系野香占。以野香占为父本、不育系平丰A为母本组配出强优势杂交组合平丰优香占。该组合对白叶枯病和细条病均表现为中抗,同时中抗稻瘟病,米质达到部标2级优质米标准。【结论】抗水稻白叶枯病兼抗细条病的xa5基因具有部分显性效应,可用于杂交水稻育种改良;培育出含有野生稻血缘的野香占能组配出中抗白叶枯病和细条病强优势水稻杂交组合,有助于丰富和拓宽水稻育种遗传基础。

First Report of Botryosphaeria dothidea Causing Sweet Osmanthus Leaf Dieback in China

Sweet osmanthus is one of the ten traditional famous flowers in China.The occurrence of the diseases caused by fungi other than Botryosphaeria spp.has been reported mainly from China on sweet osmanthus.A leaf dieback of sweet osmanthus caused by Botryosphaeria sp.was found for the first time in 2007 in Nanning City,Guangxi,China.The objectives of the present study were to isolate and characterize the causal organism of sweet osmanthus leaf dieback.The fungus was isolated from the lesions of affected sweet osmanthus leaves and its pathogenicity to sweet osmanthus was confirmed using a detached-leaf-inoculation method.The identification of the pathogen was carried out mainly based on the morphological characters and molecular analysis of internal transcribed spacer （ITS） sequences.The morphological characters of the pathogenic isolate GHX6 were agreed with that of Botryosphaeria dothidea.The ITS sequence of the isolate was amplified with primers ITS1 and ITS4,and submitted to GenBank （accession no.GQ368251）.Molecular analysis based on ITS sequence comparison between the isolate GHX6 and the other related fungi derived from GenBank supported that the causal agent of the sweet osmanthus leaf dieback belonged to Botryosphaeria dothidea.This is the first report of Botryosphaeria dothidea causing leaf dieback on sweet osmanthus in China.

一株高效甘蔗内生固氮菌NN08200的鉴定及其对甘蔗的促生长作用

【背景】生产上过高的氮肥投入是我国农业可持续发展的重要限制因子之一。利用生物固氮是减少氮肥施用量最为有效的途径,植物内生固氮菌资源的挖掘和利用对我国农业可持续发展具有重要实践意义。【目的】筛选高效甘蔗内生固氮菌,并对其联合固氮效率及促生长功能进行评价。【方法】从广西甘蔗茎基部组织分离筛选到一株内生固氮菌株NN08200,利用乙炔还原法测定固氮酶活性,通过菌落PCR扩增nif H基因确定菌株为固氮菌;通过菌株培养性状和菌体形态观察、Biolog细菌鉴定系统和16SrRNA基因序列分析确定该菌株的分类;采用盆栽接种测定菌株对甘蔗的实际促生长作用,并利用15N同位素稀释法测定其相对固氮效率。【结果】菌株NN08200的固氮酶活性达到2445nmolC2H4/(h·m L),菌株的nif H基因长度为339bp,与甘蔗内生固氮醋酸杆菌Gluconacetobacter diazotrophicus PAL5菌株的nif H相似性达99%;根据菌株培养性状和菌体形态观察、Biolog细菌鉴定系统和16SrRNA基因序列分析结果,菌株NN08200属于泛菌属(Pantoeasp.)细菌;盆栽接种菌株NN08200能显著提高甘蔗幼苗的株高和干重,15N同位素分析结果表明接种该菌株甘蔗植株的根、茎和叶从空气中获得氮素的百分率分别为7.49%、15.02%和10.79%,其联合固氮效率显著优于甘蔗内生固氮模式菌株G. diazotrophicus PAL5,利用后者接种的甘蔗根、茎和叶从空气中获得氮的百分率分别为3.53%、9.44%和4.87%。【结论】菌株Pantoea sp. NN08200是高效甘蔗内生固氮菌,其固氮促生长效果明显高于G. diazotrophicus PAL5菌株,可望研发成为优良固氮微生物肥料生产菌种,并可进一步用于甘蔗联合固氮菌作用机理的相关研究。