Immunodetection of Two Curtoviruses Infecting Sugar Beet

Beet leafhopper-transmitted curly top virus is a serious problem in many different crops in the semiarid western U.S., including sugar beet, tomatoes and beans. Curly top is caused by a genetically diverse complex of phloem-limited curtoviruses. Due to the phloem restriction of curtoviruses and the lack of a convenient laboratory host-vector system for curly top virus propagation and purification, no commercial immunodetection tests are available for curtoviruses. Routine diagnostics for curly top relies either on visual symptoms or PCR tests. Lack of an ELISA test system is one of the factors hampering development and screening of the curly top resistant germplasm in, for instance, sugar beet and bean breeding programs. To fill in this gap, we developed an ELISA based detection system for curtoviruses which utilizes virus-specific antibodies generated against bacterially-expressed CP of Beet mild curly top virus. Bacterially-expressed CP was affinity purified and used as an antigen for antibody production in two animal species. Specificity of the resulting antisera was tested in Western blots and various triple-antibody sandwich (TAS)-ELISA formats with sugar beet, bean and Nicotiana benthamiana leaf tissue. We demonstrate reliable detection of two curtoviruses in different crops in TAS-ELISA format, suitable for large-scale screening of germplasm in breeding programs

Immunodetection of Two Curtoviruses Infecting Sugar Beet

Beet leafhopper-transmitted curly top virus is a serious problem in many different crops in the semiarid western U.S., including sugar beet, tomatoes and beans. Curly top is caused by a genetically diverse complex of phloem-limited curtoviruses. Due to the phloem restriction of curtoviruses and the lack of a convenient laboratory host-vector system for curly top virus propagation and purification, no commercial immunodetection tests are available for curtoviruses. Routine diagnostics for curly top relies either on visual symptoms or PCR tests. Lack of an ELISA test system is one of the factors hampering development and screening of the curly top resistant germplasm in, for instance, sugar beet and bean breeding programs. To fill in this gap, we developed an ELISA based detection system for curtoviruses which utilizes virus-specific antibodies generated against bacterially-expressed CP of Beet mild curly top virus. Bacterially-expressed CP was affinity purified and used as an antigen for antibody production in two animal species. Specificity of the resulting antisera was tested in Western blots and various triple-antibody sandwich (TAS)-ELISA formats with sugar beet, bean and Nicotiana benthamiana leaf tissue. We demonstrate reliable detection of two curtoviruses in different crops in TAS-ELISA format, suitable for large-scale screening of germplasm in breeding programs

Deletion of the unique gene encoding a typical histone H1 has no apparent phenotype in Aspergillus nidulans

We have cloned the H1 histone gene (hhoA) of Aspergillus nidulans. This single-copy gene codes for a typical linker histone with one central globular domain. The open reading frame is interrupted by six introns. The position of the first intron is identical to that of introns found in some plant histones. An H1–GFP fusion shows exclusive nuclear localization, whereas chromosomal localization can be observed during condensation at mitosis. Surprisingly, the deletion of hhoA results in no obvious phenotype. The nucleosomal repeat length and susceptibility to micrococcal nuclease digestion of A. nidulans chromatin are unchanged in the deleted strain. The nucleosomal organization of a number of promoters, including in particular the strictly regulated niiA-niaD bidirectional promoter is not affected.This work was supported by EC grant BIO2-CT93-0147, the CNRS and the Université Paris Sud. M.I.M-P. has been the recipient of CE fellowship BIO-CT-94-8102 and a fellowship from the Fondation pour la Recherche Médicale. R.G. has been the recipient of CE fellowship BIO4-CT-96-5010Peer reviewe