Characterization and function analysis of Hsp60 and Hsp10 under different acute stresses in black tiger shrimp, <Emphasis Type="Italic">Penaeus monodon</Emphasis>

Heat shock proteins (Hsps) are a class of highly conserved proteins produced in virtually all living organisms from bacteria to humans. Hsp60 and Hsp10, the most important mitochondrial chaperones, participate in environmental stress responses. In this study, the full-length complementary DNAs (cDNAs) of Hsp60 (PmHsp60) and Hsp10 (PmHsp10) were cloned from Penaeus monodon. Sequence analysis showed that PmHsp60 and PmHsp10 encoded polypeptides of 578 and 102 amino acids, respectively. The expression profiles of PmHsp60 and PmHsp10 were detected in the gills and hepatopancreas of the shrimps under pH challenge, osmotic stress, and heavy metal exposure, and results suggested that PmHsp60 and PmHsp10 were involved in the responses to these stimuli. ATPase and chaperone activity assay indicated that PmHsp60 could slow down protein denaturation and that Hsp60/Hsp10 may be combined to produce a chaperone complex with effective chaperone and ATPase activities. Overall, this study provides useful information to help further understand the functional mechanisms of the environmental stress responses of Hsp60 and Hsp10 in shrimp.     

A betaine aldehyde dehydrogenase gene in quinoa (<Emphasis Type="Italic">Chenopodium quinoa</Emphasis>): structure,phylogeny, and expression pattern

Betaine aldehyde dehydrogenase (BADH) is widely considered as a key enzyme in glycine betaine metabolism in higher plants. Several paralogous genes encoding different isozymes of BADH have been identified and characterized in some plants; however, until now, only limited information is available about BADH genes in quinoa (Chenopodium quinoa). Here, we report the molecular cloning, structural organization, phylogenetic evolution, and expression profile of a BADH gene (CqBADH1) from quinoa. The translated putative CqBADH1 protein included five conserved features of the ALDH Family 10. Comparisons between the cDNA and genomic sequences revealed that the CqBADH1 gene contained 15 exons and 14 introns. Comparative screening of introns in homologous genes demonstrated that the number and position of the BADH introns were highly conserved among the BADH genes in Amaranthaceae plants and in other more distantly related plant species. A phylogenetic analysis showed that CqBADH1 had the closest relationship with a protein from Atriplex canescens and belonged to the ALDH10 family. Expression profile analyses indicated that CqBADH1 was expressed only in root, and showed time-dependent expression profiles under NaCl-stress condition. Moreover, in quinoa, NaCl stress led to increased levels of CqBADH1 mRNA accompanied by the accumulation of glycine betaine. This is the first study to describe a BADH gene in quinoa.     

Molecular characterization and expression analysis of <Emphasis Type="Italic">Hsp90</Emphasis> in <Emphasis Type="Italic">Schizothorax prenanti</Emphasis>

Aquatic animals suffer from various environmental stresses because the aquatic environment is a very complex system. To monitor the health status of fish, Hsp90 a potential early warning marker was determined in Schizothorax prenanti after infection with a bacterium. In this study, we cloned Hsp90 from S. prenanti for the first time. The full-length cDNA sequence of SpHsp90 was 2663 bp, contains an open reading frame of 2181 bp, and has a gene encoding 726 amino acids, an estimated molecular mass of 83.38 kDa, and a theoretical isoelectric point of 4.91. The SpHsp90 amino acid sequence has five conserved HSP90 family signatures and shares 87.0–95.5 % identity with other vertebrates. Phylogenetic analysis and structure comparison indicated that SpHsp90 should be a β isoform of the HSP90 family. SpHsp90 was ubiquitously expressed in all examined tissues, and the highest level of expression was in the kidney. After Streptococcus agalactiae infection, the level of SpHsp90 expression had significant changes (P < 0.05) in the hepatopancreas, spleen, kidney, and blood. The expression increased to the highest level at 6 h in the blood and at 24 h in the hepatopancreas, spleen, and kidney. The results suggested that the SpHsp90 gene could be induced by S. agalactiae in S. prenanti and that SpHsp90 may be involved in resistance to bacterial infection and provide an early warning information. The kidney is the most suitable for detecting SpHsp90 after bacterial infection.     

Cloning and characterization of the new multiple stress responsible gene I (<Emphasis Type="Italic">MuSI</Emphasis>) from sweet potato

New multiple-stress related gene isolated from sweet potato and designated it as MusI (multiple stress responsible gene I). Sequence analysis revealed that its full length cDNA was 998 bp long and included a 717 bp open reading frame encoding for 238 amino acids. Comparison of its cDNA and genomic DNA sequence showed that 3 exons were divided by 2 introns in its ORF region. Its deduced amino acid sequence contained a conserved rubber elongation factor (REF) domain and showed high homology with many stress-related proteins. Therefore, it was named MuSI (multiple stress responsible gene I). Southern hybridization analysis indicated that the MuSI gene may belong to a multi-gene family. Expression pattern of the MuSI gene showed that it was differently expressed among roots, stems, leaves, and flowers of a sweet potato, and its expression level was especially high in flowers and white fibrous roots. Its expression was also highly induced by various stress signals including dehydration, high salt, heavy metal, oxidation, and plant hormones. Stress tolerance experiment using transgenic plants overexpressing the MuSI gene showed that all independent transgenic tobacco lines have enhanced tolerance to high temperature stress. Among them, transgenic line 6 particularly showed tolerance to salt, heavy metal, and osmotic stress as well. These results suggest that the MuSI gene functions as a positive regulator of various stress responses and may be useful in improving stress tolerance of transgenic plants.     

Early characterization of somatic hybrids from symmetric protoplast electrofusion of <Emphasis Type="Italic">Solanum pinnatisectum</Emphasis> Dun. and <Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.

Variability of 31 somatic hybrids of Solanum pinnatisectum Dun. with Solanum tuberosum L. for leaf morphology, plant vigor, resistance to Phytophthora infestans, ploidy level, and cytoplasm type was evaluated in vitro. The composition of these somatic hybrids was as follows: [S. pinnatisectum Dun. (2n = 2x = 24; cytoplasmic type Wγ) + S. tuberosum L. (2n = 4x = 48; cytoplasmic type Tß)]. Based on leaf morphology and plant growth vigor, plants were divided into three groups, including plants close to tbr parent with unlobed leaves, small plants with scarcely dissected leaves, and vigorous plants with asymmetrically and pinnately lobed leaves. Nine of the somatic hybrids were found to be highly resistant to P. infestans. Somatic hybrids were either tetraploid or hexaploid, with hexaploids being predominant. The cytoplasm of somatic hybrids was either Tßγ or Wßγ, with Tßγ being more common. Overall, in contrast to leaf morphology and growth vigor, level of resistance to P. infestans was not related to either ploidy level or type of cytoplasm. These findings demonstrate that early in vitro selection of promising hybrids can be useful in breeding programs.     

An ATP-Binding Cassette Transporter Gene from <Emphasis Type="Italic">Cucumis sativus</Emphasis> L., <Emphasis Type="Italic">CsABC19</Emphasis>, Is Involved in Propamocarb Stress in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

A propamocarb-responsive gene named CsABC19 was isolated from a cucumber cultivar ‘D0351’ using a homologous cloning strategy. The full-length cDNA of CsABC19 was 921 bp with a complete ORF encoding 306 amino acids. Quantitative real-time PCR analysis revealed that CsABC19 was induced in the root, stem, leaf, and fruit by propamocarb and the expression levels of CsABC19 seemed to be different in different tissues. Further functional analysis showed that CsABC19 transgenic Arabidopsis plants appeared better growth performance under propamocarb stress and lower propamocarb residues. Our findings suggest that CsABC19 plays a crucial role in plant responses to propamocarb stress and also provide new clues for the mechanism regulation of the responses to propamocarb stress in cucumber.