New evidence on the state of stress of the san andreas fault system

Contemporary in situ tectonic stress indicators along the San Andreas fault system in central California show northeast-directed horizontal compression that is nearly perpendicular to the strike of the fault. Such compression explains recent uplift of the Coast Ranges and the numerous active reverse faults and folds that trend nearly parallel to the San Andreas and that are otherwise unexplainable in terms of strike-slip deformation. Fault-normal crustal compression in central California is proposed to result from the extremely low shear strength of the San Andreas and the slightly convergent relative motion between the Pacific and North American plates. Preliminary in situ stress data from the Cajon Pass scientific drill hole (located 3.6 kilometers northeast of the San Andreas in southern California near San Bernardino, California) are also consistent with a weak fault, as they show no right-lateral shear stress at approximately 2-kilometer depth on planes parallel to the San Andreas fault.     

Tuber quality and soft rot resistance of hybrids betweenSolarium tuberosum and the incongruent wild relativeS. commersonii

Tetraploid BC₃ hybrids between sexually incompatible speciesSolanum commersonii andS. tuberosum were characterized for tuber quality (stolon length, tuber eye depth, chipping color from 3-month storage at 5 C, and specific gravity) and soft rot resistance traits. For all analysed morphological traits, except stolon length, genotypes resembled theS. tuberosum phenotype. On average, the specific gravity of selected genotypes was quite high (1.087), and 12 of them had a value >1.090. As for chipprocessing ability, 4.8% of genotypes chipped well directly from cold storage, and 14.3% after reconditioning. All but one of these genotypes also possessed a high specific gravity of tubers. Variability was found for resistance toErwinia carotovora subsp.carotovora. In particular, 24% of hybrids had a rotted area diameter ≤ 4 mm and were classified as resistant. The average percentage ofcommersonii-specific markers still present in the BC₃ hybrids was 22%, ranging from 9% to 37%. Genotypes combining good qualitative tuber traits with a wild genome content lower than the average value of the population were selected for further breeding efforts. The importance of molecular-assisted selection is discussed.     

Strong increase of foliar inulin occurs in transgenic lettuce plants (Lactuca sativa L.) overexpressing the Asparagine Synthetase A gene from Escherichia coli

Transgenic lettuce (Lactuca sativa L. cv. 'Cortina') lines expressing the asparagine synthetase A gene from Escherichia coli were produced to alter the plant nitrogen status and eventually enhance growth. The relative molecular abundance of water-soluble metabolites was measured by 1H NMR in transgenic and conventional plants at early developmental stages and grown under the same conditions. NMR metabolic profiles assessed that a transgenic line and the wild-type counterpart shared the same compounds, but it also revealed side effects on the carbon metabolism following genetic modification. Concerning the nitrogen status, the amino acid content did not vary significantly, except for glutamic acid and gamma-aminobutyric acid, which diminished in the transgenics. As for the carbon metabolism, in transgenic leaves the contents of sucrose, glucose, and fructose decreased, whereas that of inulin increased up to 30 times, accompanied by the alteration of most Krebs's cycle organic acids and the rise of tartaric acid compared to nontransformed controls. Lettuce leaf inulins consisted of short oligomeric chains made of one glucose unit bound to two/four fructose units. Inulins are beneficial for human health, and they are extracted from plants and commercialized as long-chain types, whereas the short forms are synthesized chemically. Hence, lettuce genotypes with high content of foliar short-chain inulin represent useful materials for breeding strategies and a potential source for low molecular weight inulin.