Sustainable agriculture is a prerequisite for food and environmental security. Chemical fertilization, especially nitrogenous fertilization, is considered the most consumed for field crops. In rice crops, plants consume much less than half of the applied N-fertilizer. In the current investigation, multiple N environments were generated by applying different N doses of urea fertilizer to a permanent transplanted field for two successive summer growing seasons at a rice research and training center, Kafrelsheikh, Egypt. A set of 55 genotypes consisting of 25 Jabonica, 4 Tropical Japonica, 20 Indica, and 6 Indica/Japonica were transplanted under no N (0N), Low N (LN), medium N (MN), and High N (HN) (i.e., 0, 48, 96, and 165 Kg N ha−1, respectively). Highly significant differences were detected among the tested genotypes. AMMI analysis of variance revealed the existence of the genotype via nitrogen interaction (GNI) on yield performance. The GNI principal components (IPCA) IPCA1 and IPCA2 scores were significant and contributed values of 71.1 and 21.7, respectively. The highest-ranked genotypes were MTU1010, IR22, SK2046, SK2058, IR66, and Yabani LuLu based on their grain yield means (30.7, 29.9, 29.5, 29.3, 28.8, and 28.5 g plant−1). These genotypes were grouped into the same SCL according to the stability analysis ranking matrix. Based on AMMI analysis and biplots, MTU1010 and Yabani LuLu showed yield stability across environments. Meanwhile, the which-won-where biplot showed that IR22 was superior under unfavorable N-levels and MTU1010 was stable across the different environments. These findings are considered to be of great importance to breeders for initiating low-nitrogen-input breeding programs for sustainable agriculture.

Earlier reports had suggested that the large T antigen expressed in simian virus 40 (SV40)-transformed mKS-A cells may be replication defective. Our experiments support these earlier observations showing that the mKS-A T antigen has a reduced DNA-unwinding activity in vitro. To investigate the molecular basis for this defect, we have isolated from an mKS-A genomic library an EMBL-3 bacteriophage clone carrying in its insert a full-length SV40 DNA element that most likely encodes the expressed T-antigen variant. DNA sequencing revealed only one nonconservative amino acid exchange, Asp to Asn at residue 636. Surprisingly, when a plasmid clone carrying the mKS-A T-antigen-coding sequence was transfected into monkey cells, we found that it replicated quite efficiently, probably suggesting that a high nuclear concentration of the variant T-antigen form compensates for the partial biochemical defect. However, a high nuclear concentration of T antigen was also found in mKS-A T-antigen-transformed mouse cells, yet a fusion of these cells to permissive monkey cells failed to induce in situ replication and excision of integrated SV40 DNA. We discuss possible reasons for the different behavior of T antigen in monkey cells and in mouse cells and suggest that one possibility for the replication-negative phenotype in transformed cells may be related to the fact that T antigen forms a tight complex with the cellular p53 protein in mouse cells but not in monkey cells.

The present study was carried out to identify the best cross(es) for Orobanche tolerance using genetic variance components and molecular analyses among four parents of faba bean, their six F 1 crosses and six F 2 populations which were produced via half-diallel mating design under Orobanche infected soil condition. Significant mean squares were recorded for parents and crosses for the studied traits. The GCA/SCA ratio was higher than unity for all studied traits, except for number of Orobanche spikes/plant and 100-seed weight. Highly significant positive and negative correlation coefficients were obtained among almost studied traits. Broad sense heritability ranged from intermediate to high and from low to intermediate for narrow sense. Five RAPD and five SSR primers were used for marker-assisted selection for Orobanche tolerance in parents and their F 2 populations. In the case of RAPD primers, three of them showed higher resolving power (RP) rates and were found to be more suitable for genetic diversity analysis in the genotypes under study. In the case of SSR markers, the average value of resolving power was 5.24 per primer. Moreover, primer GA4 was found to be the most suitable for genetic diversity analysis among genotypes under study while, it recorded the highest RP value (7.64). The average values of polymorphic information content were 0.27 and 0.34 per primer based on RAPD and SSR data, respectively. The molecular distance among four faba bean parents and their F 2 bulks ranged from 0.099 to 0.556 by using RAPD and SSR combined data. Positive genotype-specific markers were recorded in some genotypes with molecular sizes ranged from 180 bp to 1584 bp by using both DNA markers. These positive specific markers may play important roles in Orobanche tolerance in faba bean.

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