小麦亲缘种属添加系耐低磷胁迫性状鉴定与基因染色体定位

采用苗期缺磷和全营养对照处理,以70个中国春—野生亲缘种属二体添加系及中国春为材料,根据苗期表观遗传性状、磷吸收率和利用率相对生物量对其进行耐低磷胁迫能力筛选鉴定和基因染色体定位。结果表明:大麦4H和长穗偃麦草7E染色体上携带有耐低磷胁迫的优异基因;长穗偃麦草6E、黑麦1R和6R、卵穗山羊草4Ug和6Mg、易变山羊草4Sv染色体携带促进小麦根系生长发育的基因;拟斯比尔托山羊草5S和簇毛麦4V染色体分别携带高磷吸收率和磷利用率的基因。通过染色体工程技术,可以将携带耐低磷胁迫基因的外源染色体片段导入普通小麦,为小麦耐低磷胁迫育种和了解植物耐低磷胁迫的分子机理奠定基础。     

Host‐associated genomic differentiation in congeneric butterflies: now you see it,now you do not

Ecotypic variation among populations may become associated with widespread genomic differentiation, but theory predicts that this should happen only under particular conditions of gene flow, selection and population size. In closely related species, we might expect the strength of host‐associated genomic differentiation (HAD) to be correlated with the degree of phenotypic differentiation in host‐adaptive traits. Using microsatellite and Amplified Fragment Length Polymorphism (AFLP) markers, and controlling for isolation by distance between populations, we sought HAD in two congeneric species of butterflies with different degrees of host plant specialization. Prior work on Euphydryas editha had shown strong interpopulation differentiation in host‐adapted traits, resulting in incipient reproductive isolation among host‐associated ecotypes. We show here that Euphydryas aurinia had much weaker host‐associated phenotypic differentiation. Contrary to our expectations, we detected HAD in Euphydryas aurinia, but not in E. editha. Even within an E. aurinia population that fed on both hosts, we found weak but significant sympatric HAD that persisted in samples taken 9 years apart. The finding of significantly stronger HAD in the system with less phenotypic differentiation may seem paradoxical. Our findings can be explained by multiple factors, ranging from differences in dispersal or effective population size, to spatial variation in genomic or phenotypic traits and to structure induced by past histories of host‐adapted populations. Other infrequently measured factors, such as differences in recombination rates, may also play a role. Our result adds to recent work as a further caution against assumptions of simple relationships between genomic and adaptive phenotypic differentiation.     

Salmonella: Now you see it,now you don't

Diseases caused by Salmonella species are characterized by bacterial invasion of host cells. Salmonella invasion requires a genetic locus (inv) with homology to bacterial systems involved in specific protein export and organelle assembly. Until recently, the actual Salmonella invasion factors exported or assembled by the inv system remained unidentified. It now appears that Salmonella produces novel appendages upon contact with host cells. These appendages are transient, appearing and disappearing rapidly from the bacterial surface. Appendages are altered in strains unable to invade due to mutations within the inv/spa locus. Therefore, a role for the invasion locus has been identified, providing another example of bacterial pathogens responding to signals provided by the host cell surface.