Manipulating duckweed through genome duplication.

Significant inter- and intraspecific genetic variation exists in duckweed, thus the potential for genome plasticity and manipulation is high. Polyploidy is recognised as a major mechanism of adaptation and speciation in plants. We produced several genome-duplicated lines of Landoltia punctata (Spirodela oligorrhiza) from both whole plants and regenerating explants using a colchicine-based cocktail. These lines stably maintained an enlarged frond and root morphology. DNA ploidy levels determined by florescence-activated cell sorting indicated genome duplication. Line A4 was analysed after 75 biomass doublings. Frond area, fresh and dry weights, rhizoid number and length were significantly increased versus wild type, while the growth rate was unchanged. This resulted in accumulation of biomass 17-20% faster in the A4 plants. We sought to determine if specific differences in gene products are found in the genome duplicated lines. Non-targeted ultra performance LC-quadrupole time of flight mass spectrometry was employed to compare some of the lines and the wild type to seek identification of up-regulated metabolites. We putatively identified differential metabolites in Line A65 as caffeoyl hexoses. The combination of directed genome duplication and metabolic profiling might offer a path for producing stable gene expression, leading to altered production of secondary metabolites.

Attention-deficit hyperactivity disorder (ADHD) as a pyridoxine-dependent condition: urinary diagnostic biomarkers.

The data obtained in children with different forms of epilepsy allowed us to consider epilepsy as an inborn error of pyridoxine (vitamin B6) metabolism (Dolina et al., 2012). Mutual interconnections between ADHD and epilepsy indicate that such an approach is reasonable for ADHD. To check such an assumption we analyzed in ADHD patients the same parameters of pyridoxal phosphate (PLP)-dependent tryptophan (TRP) degradation, which were analyzed in epileptic children. The level of TRP and concentrations of compounds formed or metabolized by TRP degradation, the ratios between some of them, and the level of 4-pyridoxic acid were HPLC detected in ADHD children and healthy controls. The data obtained, including low values of 4PA/TRP, IND/TRP and IND/KYN ratios, have evidenced dramatically impaired activity of pyridoxine-dependent enzymes in ADHD patients. Ritalin treatment did not change the general pattern of TRP degradation, but still created a kind of balance between some of detected metabolites. However, the 4PA/TRP, IND/TRP and IND/KYN ratios remained as low as in untreated patients, keeping the importance of diagnostic markers. Almost identical parameters of TRP degradation in untreated ADHD and epileptic patients allow to assume that inborn disorders of vitamin B6 metabolism are the common biochemical background of both diseases. The disturbed activity of PLP dependent enzymes apparently forms those profound disturbances of neurotransmitter systems, which are inherent in ADHD: low concentrations of monoamines and disordered amino acid metabolism. If vitamin B6 disorders are the core biochemical disturbances inherent in ADHD, then the long-term pyridoxine treatment is pathogenetically based replacement therapy of the disease. According to our data, multi-year pyridoxine treatment normalizes completely the pattern of ADHD behavior, without causing any serious side effects.

Biosynthesis of antinutritional alkaloids in solanaceous crops is mediated by clustered genes.

Steroidal glycoalkaloids (SGAs) such as α-solanine found in solanaceous food plants--as, for example, potato--are antinutritional factors for humans. Comparative coexpression analysis between tomato and potato coupled with chemical profiling revealed an array of 10 genes that partake in SGA biosynthesis. We discovered that six of them exist as a cluster on chromosome 7, whereas an additional two are adjacent in a duplicated genomic region on chromosome 12. Following systematic functional analysis, we suggest a revised SGA biosynthetic pathway starting from cholesterol up to the tetrasaccharide moiety linked to the tomato SGA aglycone. Silencing GLYCOALKALOID METABOLISM 4 prevented accumulation of SGAs in potato tubers and tomato fruit. This may provide a means for removal of unsafe, antinutritional substances present in these widely used food crops.

Asymmetric adaptation to indolic and aliphatic glucosinolates in the B and Q sibling species of Bemisia tabaci (Hemiptera: Aleyrodidae).

The role glucosinolates play in defending plants against phloem feeders such as aphids and whiteflies is currently not clear as these herbivores may avoid bringing glucosinolates from the phloem sap into contact with myrosinase enzymes. Here, we investigated the effects of high levels of aliphatic and indolic glucosinolates on life history traits and detoxification gene expression in two sibling species, B and Q, of the whitefly Bemisia tabaci. High levels of aliphatic glucosinolates decreased the average oviposition rate of both species and reduced the survival and developmental rate of Q nymphs. High levels of indolic glucosinolates decreased the oviposition rate and survival of nymphal stages of the B species and the developmental rate of both species. Molecular analyses revealed two major asymmetries between the B and Q species. First, specific GST genes (BtGST1 and BtGST2) were significantly induced during exposure to indolic glucosinolates only in Q. This may reflect the genes putative involvement in indolic glucosinolates detoxification and explain the species' good performance on plants accumulating indolic glucosinolates. Second, the constitutive expression of eight of the 10 detoxification genes analysed was higher in the Q species than in the B species. Interestingly, four of these genes were induced in B in response to high levels of glucosinolates. It seems, therefore, that the B and Q species differ in their 'optimal defence strategy'. B utilizes inducible defences that are profitable if the probability of experiencing the stress is small and its severity is low, while Q invests significant resources in being always 'ready' for a challenge.