Identification of alleles of carotenoid pathway genes important for zeaxanthin accumulation in potato tubers

We have investigated the genetics and molecular biology of orange flesh colour in potato (Solanum tuberosum L.). To this end the natural diversity in three genes of the carotenoid pathway was assessed by SNP analyses. Association analysis was performed between SNP haplotypes and flesh colour phenotypes in diploid and tetraploid potato genotypes. We observed that among eleven beta-carotene hydroxylase 2 (Chy2) alleles only one dominant allele has a major effect, changing white into yellow flesh colour. In contrast, none of the lycopene epsilon cyclase (Lcye) alleles seemed to have a large effect on flesh colour. Analysis of zeaxanthin epoxidase (Zep) alleles showed that all (diploid) genotypes with orange tuber flesh were homozygous for one specific Zep allele. This Zep allele showed a reduced level of expression. The complete genomic sequence of the recessive Zep allele, including the promoter, was determined, and compared with the sequence of other Zep alleles. The most striking difference was the presence of a non-LTR retrotransposon sequence in intron 1 of the recessive Zep allele, which was absent in all other Zep alleles investigated. We hypothesise that the presence of this large sequence in intron 1 caused the lower expression level, resulting in reduced Zep activity and accumulation of zeaxanthin. Only genotypes combining presence of the dominant Chy2 allele with homozygosity for the recessive Zep allele produced orange-fleshed tubers that accumulated large amounts of zeaxanthin

Wirkung von UV-Strahlung auf das Wachstum von Keimlingen und die Zusammensetzung und photosynthetische Aktivitaet von Blaettern und isolierten Chloroplasten

SIGLETIB: RA 6464 (5) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Untersuchungen ueber den Einfluss erhoehter UV-B-Strahlung auf Entwicklung, Zusammensetzung, Struktur und Funktion von Pflanzen Status- und Abschlussbericht 1979-1981

SIGLEDEGerman

Ueber die Wirkung erhoehter UV-B-Strahlung in Kombination mit anderen Stressfaktoren auf Wachstum und Funktion von Nutzpflanzen Abschlussbericht

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Internal Filters : Prospects for UV-Acclimation in Higher Plants

Wavelength-selective absorption of solar radiation within plant leaves allows penetration of visible radiation to the chloroplats, while removing much of the damaging ultraviolet-B radiation. Flavonoids are important in this wavelength-selective absorption. Induction of flavonoid synthesis by solar radiation, and specifically by UV-B radiation, is discussed as this relates to the potential acclimation of plants to enhanced solar UV-B radiation that would result from stratospheric ozone reduction

Variability of bioassays with metsulfuron-methyl in soil

A total of 74 independently run bioassays with soil incorporated metsulfuron-methyl from 12 different laboratories was analysed by a logistic dose-response curve to assess the precision of regression parameters and relate ED(50) to soil properties. The potency in terms of ED(50) of metsulfuron-methyl in Brassica rapa L., which was used by all laboratories, varied between 0.05 and 3.9 g a.i. ha(-1). ED(5)0 was negatively correlated with pH and positively correlated with organic matter. The majority of laboratories had EDso within the interval 0.1-1.0 g a.i. ha(-1). At one laboratory using three test species, the most sensitive species was Beta vulgar's L. followed by Brassica rapa L, and Lepidium sativum L. The coefficients of variation were smallest for the ED(50) and ED(90) response levels and largest for the ED(10). The slope of the response curves had considerably lower coefficients of variation than the EDs. The results are discussed in relation to a previous collaborative bioassay study. Finally it is suggested that standardization of bioassays with herbicides could be achieved in the same way as standardization of chemical analyses