Transcriptional profiling of embryogenic callus produced from Medicago truncatula mesophyll protoplasts indicated upregulation of ethylene biosynthesis and ethylene response genes. Using inhibitors of ethylene biosynthesis and perception, it was shown that ethylene was necessary for somatic embryogenesis (SE) in this model legume. We chose several genes involved in ethylene biosynthesis and response for subsequent molecular analyses. One of these genes is a gene encoding a transcription factor that belongs to the AP2/ERF superfamily and ERF subfamily of transcription factors. We demonstrate that this gene, designated M. truncatula SOMATIC EMBRYO RELATED FACTOR1 (MtSERF1), is induced by ethylene and is expressed in embryogenic calli. MtSERF1 is strongly expressed in the globular somatic embryo and there is high expression in a small group of cells in the developing shoot meristem of the heart-stage embryo. RNA interference knockdown of this gene causes strong inhibition of SE. We also provide evidence that MtSERF1 is expressed in zygotic embryos. MtSERF1 appears to be essential for SE and may enable a connection between stress and development.

Random amplified polymorphic DNA (RAPD) analysis was used to evaluate the genetic diversity of elite commercial cotton varieties. Twenty two varieties belonging to Gossypium hirsutum L. and one to G. arboreum L. were analyzed with 50 random decamer primers using the polymerase chain reaction (PCR). Forty nine primers detected polymorphism in all 23 cotton varieties, while one produced monomorphic amplification profiles. A total of 349 bands were amplified, 89.1% of which were polymorphic. Cluster analysis by the unweighted pair group method of arithmetic means (UPGMA) showed that 17 varieties can be placed in two groups with a similarity ranging from 81.51% to 93.41%. G. hirsutum L. varieties S-12, V3 and MNH-93 showed a similarity of 78.12, 74.46 and 69.56% respectively with rest of the varieties. One variety, CIM-1100, showed 57.02% similarity and was quite distinct. The diploid cotton G. arboreum L. var. Ravi was also very distinct from rest of its tetraploid counterparts and showed only 55.7% similarity. The analysis revealed that the intervarietal genetic relationships of several varieties is related to their center of origin. As expected, most of the varieties have a narrow genetic base. The results obtained can be used for the selection of possible parents to generate a mapping population. The results also reveal the genetic relationship of elite commercial cotton varieties with some standard "Coker" varieties and the diploid G. arboreum L. var. Ravi (old world cotton).

Farmers occasionally need to add nitrogen fertilizer to their farms and gardens to make available just the precise nutrients for their plants' growth. The applications of inorganic nitrogen fertilizers to various crops have been continuously increasing since last many decades globally. Although nitrogen fertilizer contributes substantially to yield enhancement, but excessive use of this manure has posed serious threats to environment and human health. Rate of nitrogen fertilizers application has a close relationship with nitrate accumulation in surrounding environment, groundwater, as well as leafy and root vegetables. Consumption of diets having high nitrate contents has contributed to endogenous nitrosation, which could lead to thyroid condition, various kinds of human cancers, neural tube defects (during fetus development), and diabetes. In this short review, the authors have tried to create awareness among general public, farming community, health practitioners, and agricultural scientists for the risk involved with excessive use of nitrogen fertilizers to human health. Carcinogenic activity and other adverse effects of N-nitroso compounds might be prevented by consuming vitamin C and antioxidants containing fruits and vegetables.

Using a combination of two-dimensional gel electrophoresis (2-DE) protein mapping and mass spectrometry (MS) analysis, we have established proteome reference maps of Medicago truncatula embryogenic tissue culture cells. The cultures were generated from single protoplasts, which provided a relatively homogeneous cell population. We used these to analyze protein expression at the globular stages of somatic embryogenesis, which is the earliest morphogenetic embryonic stage. Over 3000 proteins could reproducibly be resolved over a pI range of 4-11. Three hundred and twelve protein spots were extracted from colloidal Coomassie Blue-stained 2-DE gels and analyzed by matrix-assisted laser desorption/ionization-time of flight MS analysis and tandem MS sequencing. This enabled the identification of 169 protein spots representing 128 unique gene products using a publicly available expressed sequence tag database and the MASCOT search engine. These reference maps will be valuable for the investigation of the molecular events which occur during somatic embryogenesis in M. truncatula. The proteome reference maps and supplementary materials will be available and updated for public access at http://semele.anu.edu.au/.