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Publikationen - Molekulare Signalverarbeitung

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Publikation

Kowalski, A. M.; Gooding, M.; Ferrante, A.; Slafer, G. A.; Orford, S.; Gasperini, D.; Griffiths, S. Agronomic assessment of the wheat semi-dwarfing gene Rht8 in contrasting nitrogen treatments and water regimes Field Crop Res 191, 150-160, (2016) DOI: 10.1016/j.fcr.2016.02.026

Reduced height 8 (Rht8) is the main alternative to the GA-insensitive Rht alleles in hot and dry environments where it reduces plant height without yield penalty. The potential of Rht8 in northern-European wheat breeding remains unclear, since the close linkage with the photoperiod-insensitive allele Ppd-D1a is unfavourable in the relatively cool summers. In the present study, two near-isogenic lines (NILs) contrasting for the Rht8/tall allele from Mara in a UK-adapted and photoperiod-sensitive wheat variety were evaluated in trials with varying nitrogen fertiliser (N) treatments and water regimes across sites in the UK and Spain.The Rht8 introgression was associated with a robust height reduction of 11% regardless of N treatment and water regime and the Rht8 NIL was more resistant to root-lodging at agronomically-relevant N levels than the tall NIL. In the UK with reduced solar radiation over the growing season than the site in Spain, the Rht8 NIL showed a 10% yield penalty at standard agronomic N levels due to concomitant reduction in grain number and spike number whereas grain weight and harvest index were not significantly different to the tall NIL. The yield penalty associated with the Rht8 introgression was overcome at low N and in irrigated conditions in the UK, and in the high-temperature site in Spain. Decreased spike length and constant spikelet number in the Rht8 NIL resulted in spike compaction of 15%, independent of N and water regime. The genetic interval of Rht8 overlaps with the compactum gene on 2DS, raising the possibility of the same causative gene. Further genetic dissection of these loci is required.Abbreviations    ANOVA, analysis of variance; Y, yield; HI, harvest index; GN, grain number (m−2); SS, spikelet number (spike−1); SN, spike number (m−2); HD, heading date; AN, anthesis; 12L, length of the second internode from the top; 13L, length of the third internode from the top; PAR, photosynthetically active radiation; R: FR, red: far-red light reflectance ratio; RCBD, randomised complete block design
Publikation

Elleuch, A.; Chaâbene, Z.; Grubb, D.C.; Drira, N.; Mejdoub, H.; Khemakhem, B. Morphological and biochemical behavior of fenugreek (Trigonella foenum-graecum) under copper stress Ecotoxicol Environ Saf 98, 46-53, (2013) DOI: 10.1016/j.ecoenv.2013.09.028

The effects of copper on germination and growth of fenugreek (Trigonella foenum-graecum  ) was investigated separately using different concentrations of CuSO4. The germination percentage and radical length had different responses to cupric ions: the root growth increased with increasing copper concentration up to 1 mM Cu+2Cu2+ and was inhibited thereafter. In contrast, the germination percentage was largely unaffected by concentrations of copper below 10 mM.The reduction in root growth may have been due to inhibition of hydrolytic enzymes such as amylase. Indeed, the average total amylolytic activity decreased from the first day of treatment with [Cu+2Cu2+] greater than 1 mM. Furthermore, copper affected various plant growth parameters. Copper accumulation was markedly higher in roots as compared to shoots. While both showed a gradual decrease in growth, this was more pronounced in roots than in leaves and in stems. Excess copper induced an increase in the rate of hydrogen peroxide (H2O2) production and lipid peroxidation in all plant parts, indicating oxidative stress. This redox stress affected leaf chlorophyll and carotenoid content which decreased in response to augmented Cu levels. Additionally, the activities of proteins involved in reactive oxygen species (ROS) detoxification were affected. Cu stress elevated the ascorbate peroxidase (APX) activity more than two times at 10 mM CuSO4. In contrast, superoxide dismutase (SOD) and catalase (CAT) levels showed only minor variations, only at 1 mM Cu+2Cu2+. Likewise, total phenol and flavonoid contents were strongly induced by low concentrations of copper, consistent with the role of these potent antioxidants in scavenging ROS such as H2O2, but returned to control levels or below at high [Cu+2Cu2+]. Taken together, these results indicate a fundamental shift in the plant response to copper toxicity at low versus high concentrations.
Publikation

Quint, M.; Gray, W.M. Auxin signaling Curr Opin Plant Biol 9, 448-453, (2006)

Auxin regulates a host of plant developmental and physiological processes, including embryogenesis, vascular differentiation, organogenesis, tropic growth, and root and shoot architecture. Genetic and biochemical studies carried out over the past decade have revealed that much of this regulation involves the SCFTIR1/AFB-mediated proteolysis of the Aux/IAA family of transcriptional regulators. With the recent finding that the TRANSPORT INHIBITOR RESPONSE1 (TIR1)/AUXIN SIGNALING F-BOX (AFB) proteins also function as auxin receptors, a potentially complete, and surprisingly simple, signaling pathway from perception to transcriptional response is now before us. However, understanding how this seemingly simple pathway controls the myriad of specific auxin responses remains a daunting challenge, and compelling evidence exists for SCFTIR1/AFB-independent auxin signaling pathways.
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