Plant extracts better than synthetics as meat preservatives Grape seed and pine bark extracts as additives in cooked meats perform better than synthetic preservatives in oxidation and microbial effects, say the results of a study that could be readily acceptable to consumers seeking ready-to-eat meat products with natural preservatives. The lead researcher Dr. Juhee Ahn from Ohio State University explained that in recent years, natural antimicrobial and antioxidant compounds are preferably used in meats because of their potential health benefits and safety compared with synthetic preservatives, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The new study found that grape seed extract (ActiVin) and pine bark extract (Pycnogenol) performed better that BHA and BHT in retarding the microbial contamination of freshly ground beef by E. coli, Listeria and Salmonella. The same extracts also performed better than the synthetic alternatives after nine days at reducing oxidation of the beef. The antioxidant activity of grape seed extracts has been linked to boosting cardiovascular health by limiting oxidation of LDL (bad) cholesterol, while Pycnogenol has been claimed to have beneficial effects on a wide range of medical conditions from diabetes to asthma, from boosting male fertility to improving the memory (of mice). It was found that E. coli populations on the meat decreased by only five per cent for the BHA/BHT additive, but decreased by 33 and 35 per cent, respectively, for the meat with added ActiVin and Pycnogenol. No change in Salmonella populations were seen for the BHA/BHT meats, while ActiVin and Pycnogenol reduced the bacterial population by 19 and 23 per cent, respectively. The study showed that Pycnogenol and ActiVin are promising additives for maintaining the quality and safety of cooked beef. The extracts also had a profound effect on the colour of the meats. However, the researchers noted that use of such extracts in high concentrations might impact detrimentally on the organoleptic properties of meat products and called for further research to find a balance. Website: www.foodnavigator.com

New study may help reduce the global dependence on fertilizers A team of researchers managed to trigger nodule formation in legumes without using Rhizobium bacteria. The discovery opened up the possibility of inducing nodule formation even in non-leguminous crops, which would revolutionize global farming and food production by dramatically reducing the dependence on nitrogen fertilizers. Nodule formation in legumes is triggered by a molecule called the Nod factor, present in Rhizobium, which activates a gene called DMI3. The scientists from John Innes Centre, the United Kingdom, and the Washington State University, the United States, used the legume Medicago truncatula for their experiments. They found that when a similar gene called CCaMK, found in lily, was used to replace DMI3 in M. truncatula, the new plant was still able to develop nodules in the presence of nitrogen-fixing bacteria. The team then created a mutant version of CCaMK by knocking off a part of the gene and then introducing the remainder into M. truncatula. The plant produced nodules even in the absence of Rhizobium bacteria. This led the researchers to conclude that the part of CCaMK removed was inhibiting nodule formation. Down To Earth, 15 August 2006

Bean gene works for CMV resistance in other plants To protect themselves against pathogen invasion, plants make use of specific resistance (R) genes. Studies showed that the R proteins interact with pathogen elicitors, triggering a cascade of defence responses that eventually lead a pathogen to be confined within the initial zone of infection. This localization of infection protected a plant from further damage. Dr. Young-Su Seo and colleagues of University of California Davis, the United States, have reported that a viral resistance gene from common bean functioned across plant families and was up-regulated in a non-virus-specific manner. Researchers identified viral response genes in common bean undergoing defence response to viral infection, and selected a gene designated as RT4-4 for further analysis. They introduced RT4-4 to Nicotiana benthamiana, and screened transgenic plants for resistance to bean dwarf mosaic virus (BDMV), cucumber mosaic virus (CMV), bean common mosaic virus (BCMV), bean yellow mosaic virus (BYMV) and tobacco mosaic virus (TMV). They found that most plants, whether transgenic or non-transgenic, developed disease symptoms typical to BDMV, BCMV, BYMV or TMV. However, transgenic plants developed systemic necrosis, a resistance response, when infected with seven strains of CMV from pepper or tomato, but not a CMV from bean. They traced the response to RT4-4 activity by detecting resistance responses in CMV-challenged leaves of transgenic tobacco plants. They also identified the CMV 2a gene product as the elicitor of the necrosis response. The researchers said that their approach would provide insights into the mechanisms by which plants activated pathogen-resistance responses. Website: www.mosanto.co.uk

Water-tolerant gene transferred to commercial rice varieties Scientists have identified a gene present in hardy varieties of rice that enables the crop to tolerate flooded conditions. The researchers from International Rice Research Institute in Manila, the Philippines, and the University of California Davis, the United States, have successfully introduced the gene into commercial varieties like IR-64 and Swarna and are studying if the transgenic plants could survive submergence. Most rice varieties die if fully submerged for more than four days. Submergence cuts off oxygen supply and prevents photosynthesis. But the gene Sub1A-1, found in varieties grown in Sri Lanka and India enables these plants to withstand complete submergence for 10-14 days. Rice varieties containing Sub1A-1 respond differently to stress – like switching from aerobic to anaerobic respiration or growing above the water level – but renew growth when the water level subsides. The gene controls hormonal changes related to cell elongation and carbohydrate consumption. The genes related to flood resistance or tolerance were found to be present on chromosome number 9 of the 12 rice chromosomes. The identification of Sub1A-1 is one of the significant achievements after the complete genome sequencing of rice was done almost a year ago. Down To Earth, 15 September 2006

Flavanoid-rich GM tomatoes could boost heart health Tomatoes genetically modified to have high flavonoid content reduced the levels of a protein in a mouse that is associated with inflammation, diabetes and heart disease in humans. Dr. Dietrich Rein from BASF Plant Science Holding, Germany, said that this is the first time a specific fruit has been shown to reduce human C-reactive protein (CRP) and that transgenic over-expression of specific flavonoids further reduced this important cardiovascular risk marker. The research team inserted Petunia chalcone isomerase (CHI) and Gerbera hybrida flavone synthase (FNS) genes into tomato plants to raise the flavonoid content in the tomato, and obtain the final transgenic plant, Lycopersicon esculentum cv. Feeding the peel of transgenic tomatoes to mice genetically engineered to express human CRP enabled the researchers to study the potential human health effects of these flavonoid-enriched tomatoes (flTom). CRP, produced in the liver, is a known marker for inflammation. Increased levels of CRP are a good predictor for the onset of both type-2 diabetes and cardiovascular disease. Dr. Rein and his team fed the CRP mice with a diet supplemented with 4 g/kg of flTom peel or wild tomato (wtTom). The amount of tomato fed to the mice was equivalent to a human daily intake of 2.3 g of peel or about 230 g of fresh tomato. After seven weeks of feeding, they measured levels of general health and cardiovascular risk, such as plasma CRP and cholesterol levels. It was found that consumption of either tomato peels resulted in a marked decrease in the levels of human CRP, with flTom’s effect being significantly higher. Levels of HDL-cholesterol were also up. The CRP levels in the flTom-fed mice went back to baseline levels after a two-week washout period. According to the researchers results showed that genetically engineered fruit with enhanced flavonoids levels could have anti-inflammatory effects that exceeded the effects of its wild type counterpart. They propose that it was the effect of these flavonoids on the signalling of the nuclear factor-kappa B (NF-kB), a pro-inflammatory protein that is also said to activate a variety of human cancers, which could be behind the benefits. Website: www.foodnavigator.com