Isolation and functional characterization of a Medicago sativa L. gene, MsLEA3-1

A full-length cDNA of 1,728 nt, called MsLEA3-1, was cloned from alfalfa by rapid amplification of cDNA ends from an expressed sequence tag homologous to soybean pGmPM10 (accession No. AAA91965.1). MsLEA3-1, encodes a deduced protein of 436 amino acids, a calculated molecular weight of 47.0 kDa, a theoretical isoelectric point of 5.18, and closest homology with late embryogenesis abundant proteins in soybean. Sequence homology suggested a signal peptide in the N terminus, and subcellular localization with GFP revealed that MsLEA3-1 was localized preferentially to the nucleolus. The transcript titre of MsLEA3-1 was strongly enriched in leaves compared with roots and stems of mature alfalfa plants. Gene expression of MsLEA3-1 was strongly induced when seedlings were treated with NaCl and ABA. Expression of the MsLEA3-1 transgenic was detected in transgenic tobacco. Malondialdehyde content and, electrical conductivity content were reduced and electrical conductivity and proline content were increased in transgenic tobacco compared with non-transgenic tobacco under salt stress. The results showed that accumulation of the MsLEA3-1 protein in the vegetative tissues of transgenic plants enhanced their tolerance to salt stress. These results demonstrate a role for the MsLEA3-1 protein in stress protection and suggest the potential of the MsLEA3-1 gene for genetic engineering of salt tolerance

Computational and Statistical Analyses of Amino Acid Usage and Physico-Chemical Properties of the Twelve Late Embryogenesis Abundant Protein Classes

Late Embryogenesis Abundant Proteins (LEAPs) are ubiquitous proteins expected to play major roles in desiccation tolerance. Little is known about their structure - function relationships because of the scarcity of 3-D structures for LEAPs. The previous building of LEAPdb, a database dedicated to LEAPs from plants and other organisms, led to the classification of 710 LEAPs into 12 non-overlapping classes with distinct properties. Using this resource, numerous physico-chemical properties of LEAPs and amino acid usage by LEAPs have been computed and statistically analyzed, revealing distinctive features for each class. This unprecedented analysis allowed a rigorous characterization of the 12 LEAP classes, which differed also in multiple structural and physico-chemical features. Although most LEAPs can be predicted as intrinsically disordered proteins, the analysis indicates that LEAP class 7 (PF03168) and probably LEAP class 11 (PF04927) are natively folded proteins. This study thus provides a detailed description of the structural properties of this protein family opening the path toward further LEAP structure - function analysis. Finally, since each LEAP class can be clearly characterized by a unique set of physico-chemical properties, this will allow development of software to predict proteins as LEAPs

Effect of photosynthetic photon flux density on growth, photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of Dieffenbachia cultivars

The effects of 35, 70 and 100 µmol m−2 s−1 photosynthetic photon flux density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dieffenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 µmol m−2 s−1), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photosynthesis were also optimal in plants grown under the highest irradiance. Stomatal resistance, transpiration rate and Fv/Fm values decreased with the incremental light irradiance. Activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 µmol m−2 s−1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all light treatments. These results depict that lower PPFD (35 µmol m−2 s−1) was suitable for acclimatization of Dieffenbachia plants. High PPFD (>70 µmol m−2 s−1) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels

Properties and regulation of biosynthesis of cottonseed storage proteins. Comprehensive progress report, December 1, 1976 to September 1, 1979

The regulation of gene expression in cotton seed embryogenesis was studied by attempting to define what gene products are likely to be highly regulated during this developmental progression. The flow of nitrogen into the free amino acids pools of the developing cotyledons, and into the principal nitrogen nutritional reserve of the seed, the storage proteins was measured. This was continued by following the flow of nitrogen from the storage proteins to the principal exported amino acid asparagine that occurs during the first several days of germination. In this fashion the rise and fall of certain enzymes of amino acid intermediary metabolism could be postulated, and in some cases, verified. The subsets of abundant mRNAs whose appearance and disappearance coincided with developmental events in cotyledon embryogenesis/germination with the short range goal of identifying proteins/enzyme activities were delineated as well as their mRNAs that represent specific developmental stages and the long range goal of using these representatives as probes for studying the mechanisms controlling the rise and fall of these mRNAs and their protein products