Utilization of spare substances of Zea mays L. seeds during germination under the combined effect of growth regulators and presence or absence of light

Functional changes in the source-sink system of maize sprouts under combination of external (light/dark) and hormonal (gibberellic acid/retardant) factors during germination were studied. It was found that the phytohormone action significantly increased the coleoptile, root and seedling length, dry matter mass of organs, both in light and in dark. Tebuconazole caused the opposite effect due to its retardant action. The inactivation of endogenous phytohormone was confirmed by less intensive use of seed substances, the minimum dry matter of root and coleoptile and lower reserve utilization rates under tebuconazole influence, in particular under photomorphogenesis condition. The non-maximum mass of cotyledons may indicate a kind of optimization of use of reserves under tebuconazole treatment. Gibberellin stimulated starch breakdown in both light and dark, but starch usage was higher in dark. The lower content of sugar in the seeds of skotomorphic plants in control and under gibberellin action was explained by intense outflow for the organogenesis needs. Gibberellin stimulated the hydrolysis of reserve protein after intensive starch hydrolysis in dark. Specific gibberellin regulation of phosphorus outflow for the organogenesis processes under the photo- and skotomorphogenesis conditions and no regulation for potassium under photomorphogenesis conditions were found.

Effect of gibberellin on the use of reserve substances deposited in Vicia faba L. seeds at the phase of heterotrophic development under the conditions of photo- and skotomorphogenesis

Under conditions of a combination of an external (light/dark) factor and a hormonal factor (gibberellic acid) during germination, changes in the functioning of the source-sink system in heterotrophic phase of horse beans development were studied. The increase in the epicotyl, root and seedling length, both in light and dark, as well as in the dry matter of the mass of the seedling organs, was found under drug action. Reserve substances were used more intensively under gibberellin and skotomorphogenesis influence. It is evidenced by the minimum dry matter of cotyledons and higher reserve utilization rates for root and epicotyl formation. Gibberellin stimulated starch breakdown in both, but during germination in dark, the rate of starch use was higher. Other content of sugars in skotomorphic seeds was associated with more intensive outflow for organogenesis needs: formation of root and epicotyl structures. The changes in the content of starch were higher than the changes in nitrogen content in skotomorphic and photomorphic seedlings. This indicates that gibberellin stimulates hydrolysis of reserve protein only after starch hydrolysis in dark. No specific gibberellin regulation of phosphorus and potassium outflow from seeds for organogenesis needs was found, suggesting sufficient mineral nutrients supply to ensure their re-utilization during germination, photo- and skotomorphogenesis processes.

Effects of a Reserve Protein on Spodoptera frugiperda Development: A Biochemical and Molecular Approach to the Entomotoxic Mechanism

Talisin is a storage protein from Talisia esculenta seeds that presents lectin-like and peptidase inhibitor properties. These characteristics suggest that talisin plays a role in the plant defense process, making it a multifunctional protein. This work aimed to investigate the effects of chronic intake of talisin on fifth instar larvae of Spodoptera frugiperda, considered the main insect pest of maize and the cause of substantial economic losses in several other crops. The chronic intake of talisin presented antinutritional effects on the larvae, reducing their weight and prolonging the total development time of the insects. In addition, talisin-fed larvae also showed a significant reduction in the activity of trypsin-like enzymes. Midgut histology analysis of talisin-fed larvae showed alterations in the intestinal epithelium and rupture of the peritrophic membrane, possibly causing an increase of aminopeptidase activity in the midgut lumen. Talisin also proved to be resistant to degradation by the digestive enzymes of S. frugiperda. The transcription profile of trypsin, chymotrypsin and aminopeptidase genes was also analyzed through qPCR technique. Talisin intake resulted in differential expression of at least two genes from each of these classes of enzymes. Molecular docking studies indicated a higher affinity of talisin for the less expressed enzymes.

Differential RNA- and protein-expression profiles of cactus seeds capable of hydration memory

Hydration memory is a phenomenon in which a seed can tolerate discontinuous hydration periods, displaying enhanced germination after one or multiple hydration–dehydration (HD) cycles; it was described physiologically in a few cactus species around 15 years ago. Although no additional work was done on this subject, it has great biotechnological potential since its analysis would permit predictions about whether a seed can withstand discontinuous hydration; in the long run, the knowledge about its regulation might lead to induction of this resistance, so we aimed to provide an initial approach to the molecular mechanisms that underlie hydration memory. This phenomenon was reproduced successfully in our lab with Ferocactus peninsulae seeds. Using two-dimensional (2D) electrophoresis, we compared expression patterns of proteins involved in seed maturation of seeds and seedlings subjected to an HD cycle treatment. We found differential expression of several proteins possibly involved in primary metabolism, ubiquitination pathway and reserve protein availability regulation in seeds and seedlings subjected to an HD cycle. We also found differential stability of total RNA. These results strongly suggest that the differential expression of proteins is at least partially related to the hydration memory process.

Vaccinia virus protein C4 inhibits NF-κB activation and promotes virus virulence

Vaccinia virus (VACV) strain Western Reserve protein C4 has been characterized and its function and contribution to virus virulence assessed. Bioinformatic analysis showed that C4 is conserved in six orthopoxvirus species and shares 43 % amino acid identity with VACV protein C16, a known virulence factor. A recombinant VACV expressing a C-terminally tagged version of C4 showed that, like C16, this 37 kDa protein is expressed early during infection and localizes to both the cytoplasm and the nucleus. Functional assays using a firefly luciferase reporter plasmid under the control of a nuclear factor kappa B (NF-κB)-dependent promoter demonstrated that C4 inhibits NF-κB activation at, or downstream of, the inhibitor of kappa kinase (IKK) complex. Consistent with this, C4 inhibited interleukin-1β-induced translocation of p65 into the nucleus. A VACV lacking the C4L gene (vΔC4) showed no significant differences from wild-type virus in growth kinetics or spread in cell culture, but had reduced virulence in a murine intranasal model of infection. vΔC4-infected mice exhibited fewer symptoms, lost less weight and recovered 7 days earlier than animals infected with control viruses expressing C4. Furthermore, bronchoalveolar lavage fluid from vΔC4-infected mice had increased cell numbers at day 5 post-infection, which correlated with reduced lung virus titres from this time onward. C4 represents the ninth VACV protein to inhibit NF-κB activation and remarkably, in every case examined, loss of each protein individually caused an alteration in virus virulence, despite the presence of other NF-κB inhibitors.