Beet necrotic yellow vein virus (BnYVV) is the cause of rhizomania, an important disease of sugar beetaround the world. The multipartite genome of the BNYVV contains four or five single-stranded RNA that has been used to characterize the virus. Understanding genome composition of the virus not only determines the degree of pathogenicity but also is required to development of resistant varieties of sugar beet. Resistance to rhizomania has been conferred to sugar beet varieties by conventional breeding methods or modern genome engineering tools. However, over time, viruses undergo genetic alterations and develop new variants to break crop resistance. Here, we report the occurrence of genetic reassortment and emergence of new variants of BnYVV among the isolates of thrace and Asia Minor (modern-day Turkey). Our findings indicate that the isolates harbor European A-type RNA-2 and RNA-3, nevertheless, RNA-5 is closely related to East Asian J-type. Furthermore, RNA-1 and RNA-4 are either derived from A, B, and P-types or a mixture of them. The RNA-5 factor which enhance the pathogenicity, is rarely found in the isolates studied (20%). The creation of new variants of the virus emphasizes the necessity to develop new generation of resistant crops. We anticipate that these findings will be useful for future genetic characterization and evolutionary studies of BNYVV, as well as for developing sustainable strategies for the control of this destructive disease.Rhizomania is one of the most destructive soil-borne diseases of sugar beet (Beta vulgaris L.) worldwide. Since the first report of rhizomania 1 numerous studies have reported the worldwide infection of sugar beet fields with this disease. Tamada and Baba 2 first identified Beet necrotic yellow vein virus (BNYVV) as the cause of rhizomania when they isolated the virus from infected plants of sugar beet fields in Japan. This disease reduces sugar content by 8%, root yield up to 90%, and sugar yield up to 80% 3,4 . The BNYVV genome is multipartite and composed of four single-stranded RNA species designated as RNA-1, RNA-2, RNA-3, and RNA-4, coating with a 21-kDa protein 5 . In addition, a fifth RNA species (RNA-5) has been identified in some of the European and Asian BNYVV isolates 6-12 . RNA-1 and RNA-2, which contain 6746 and 4612 nt-long RNA species, respectively, encode viral "housekeeping" genes involved in virus replication, assembly, cell-to-cell movement and suppression of post transcriptional gene silencing 13,14 . Therefore, when the virus vector Polymyxa betae Keskin 15 is not present, RNA-1 and RNA-2 are required for the maintenance of BNYVV in the environment 8,14,16 . RNA-3 consisting of a 1775 nt-long RNA species, is involved in viral pathogenicity 7,10,11,17,18 . RNA-4 (1431 nt) plays a key role in transmission of the virus by P. betae 7,11,13,19 . RNA-5 (1342-1347 nt in length) is associated with rhizomania severity, but is not required for virus survival 20,21 . Comparative studies revealed that the RNA-1, RNA-4, and RNA-5 contribute to the development ...

Sugar beet (Beta vulgaris L.) is one of the most important industrial crops throughout world. With the availability of suitable genetic transformation technologies, the yield, quality, and stress tolerance of sugar beet could be improved significantly. However, low transformation efficiencies seriously limit the application of molecular technologies to the genetic improvement of sugar beet. With the aim of improving gene transfer techniques for sugar beet, the effect of different sucrose concentrations during cocultivation on the initial Agrobacterium-mediated transformation efficiencies in sugar beet was tested. To develop an efficient experimental system through which the effect of sucrose could be tested, first, a prolific regeneration system was optimized by testing the effect of different plant growth regulators on in vitro regeneration and rooting efficiencies from sugar beet cotyledonary node explants. The highest mean number of regenerated shoots per explant was obtained when the cotyledonary node explants excised from young seedlings were grown on MS medium supplemented with 1.0 mg/L 6-benzylaminopurine. Using this regeneration system, the effect of different concentrations of sucrose included in the cocultivation medium on the initial genetic transformation efficiencies observed in T 0 plants was tested using an Agrobacterium tumefaciens strain carrying the pBin19/35S:GUS-INT construct. The inclusion of 4.5% sucrose in the cocultivation medium resulted in significantly higher transformation (34.09%) and expression efficiencies (22.72%), confirmed by polymerase chain reaction and β-glucuronidase assays, respectively, in regenerated T 0 seedlings. If translated into stably inherited transformation efficiencies, these findings could contribute to the success of genetic transformation studies in sugar beet and other crops recalcitrant to Agrobacterium-mediated transformation.

The faba bean (Vicia faba L.) is cultivated in the Mediterranean and Aegean regions only. It is a rich source of protein and an important source of food and feed for human and animal consumption. Faba beans have a narrow genetic base and their improvement through hybridization is not feasible because of high pollen self-incompatibility. This study was carried out using the embryonic axis of cv. Filiz99 and Eresen87 regenerated on MS medium containing 11 different combinations of BAP and NAA. The results showed 100% shoot regeneration frequency with maximum number of 3.3 and 3.5 shoots per explant on cv. Filiz99 and Eresen87 respectively. Regenerating shoots were rooted on 1 mg L-1 IAA. The in vitro regenerated shoots were continuously cultured for 3 weeks to acclimatize them. This approach could improve broad bean seed germination and subsequently regeneration. The results could also facilitate genetic transformation studies.

Leguminous Broad bean (Vicia faba L.) is an excellent source of minerals, vitamins and proteins that makes it highly valuable food for human and feed for animal consumption. The plant has an important characteristic to fix atmospheric Nitrogen and play an important role to establish a natural balance of N in the atmosphere. It is a highly self-pollinated plant and has problem of low variation with limited genetic pool. Moreover, the previous studies identify problem of recalcitrance in broad bean. Therefore, there is need to establish a repeatable micropropagation protocol that could ensure an increase in genetic variability to overwhelm problems in breeding. This system must also be able for efficient gene delivery and could be integrated with the conventional breeding programs through direct organogenesis. The study aimed to develop a tissue culture (shooting & rooting) protocol on two important Turkish broad bean cultivars Filiz99 and Eresen87 using MS medium containing 0.05, 0.15, 0.25, 0.35, 0.45, 0.55 mg l -1 TDZ using embryonic axis as explant. Maximum number of 5.33 and 3 shoots per explant were noted on cv. Filiz99 and Eresen87 on MS medium containing 0.15 mg l -1 TDZ. The developing shoots were rooted on MS medium containing 1 mg l -1 IAA after three weeks of culture. The rooted plants were transferred to pots containing peat under maintained under controlled greenhouse conditions for acclimatization The acclimatized plants bloomed and set seeds. Present results underscore importance of seed hydropriming before taking of explants to achieve high micropropagation on faba beans to overcome recalcitrance.