Characterization of SOD and GPX Gene Families in the Soybeans in Response to Drought and Salinity Stresses.

Plant stresses causing accumulation of reactive oxidative species (ROS) are scavenged by effective antioxidant defense systems. Therefore, the present study performed genome-wide identification of superoxide dismutase (SOD) and glutathione peroxidase (GPX) gene families in cultivated and wild soybeans, and 11 other legume species. We identified a total of 101 and 95 genes of SOD and GPX, respectively, across thirteen legume species. The highest numbers of SODs and GPXs were identified in cultivated (Glycine max) and wild (Glycine soja). A comparative phylogenetic study revealed highest homology among the SODs and GPXs of cultivated and wild soybeans relative to other legumes. The exon/intron structure, motif and synteny blocks were conserved in both soybean species. According to Ka/Ks, purifying the selection played the major evolutionary role in these gene families, and segmental duplication are major driving force for SODs and GPXs expansion. In addition, the qRT-PCR analysis of the G. max and G. soja SOD and GPX genes revealed significant differential expression of these genes in response to oxidative, drought and salinity stresses in root tissue. In conclusion, our study provides new insights for the evolution of SOD and GPX gene families in legumes, and provides resources for further functional characterization of these genes for multiple stresses.

Novel mutant camelina and jatropha as valuable feedstocks for biodiesel production.

Novel mutant camelina has become a crop of interest inspired by its short growing season, low harvesting costs and high oil composition. Despite those advantages, limited research has been done on novel mutant lines to determine applicability for biodiesel production. Jatropha is an extremely hardy, frugal and high oil yielding plant species. The major aim of the present study was not only to compare biodiesel production from jatropha and camelina but was also to test the efficacy of camelina mutant lines (M6 progenies) as superior feedstock. The biodiesel yield from camelina oil and jatropha oil was 96% and 92%, respectively. The gas chromatographic analysis using flame ionization detector (GC-FID) showed that mutant camelina oil biodiesel sample contain major amount of oleic acid (46.54 wt%) followed by linolenic acid (20.41 wt%) and linoleic acid (16.55 wt%). Jatropha biodiesel found to contain major amount of oleic acid (45.03 wt%) followed by linoleic acid (25.07 wt%) and palmitic acid (19.31 wt%). The fuel properties of produced biodiesel were found in good agreement with EN14214 and ASTM D6751 standards. The mutant camelina lines biodiesel have shown comparatively better fuel properties than jatropha. It has shown low saponification value (120.87-149.35), high iodine value (130.2-157.9) and better cetane number (48.53-59.35) compared to jatropha biodiesel which have high saponification value (177.39-198.9), low iodine value (109.7-123.1) and lesser cetane number (47.76-51.26). The results of the present student of utilizing novel mutant camelina lines for biodiesel production are quite promising and are helpful in turning out the outcomes of the previous studies suggesting that C. sativa biodiesel presents serious drawbacks for biodiesel applications.

Resistance status of Helicoverpa armigera against Bt cotton in Pakistan.

Transgenic cotton expressing the toxin Cry1Ac from Bacillus thuringiensis L. (Bt) is widely cultivated in Pakistan after its formal approval in 2010. The exposure of the local target pests to the Cry1Ac endotoxin for this duration might have changed the baseline susceptibility. To probe the status of resistance in one of the main target pests, Helicoverpa armigera, field-collected larvae were reared in the lab for conducting leaf fed bioassays. Twenty-six cotton accessions collected from farmers, including 25 Bt-cotton and one non-Bt, were tested to quantify the level of Cry1Ac, an insecticidal crystalline protein (ICP), in leaves of lower, middle and upper canopies of plants. The concentration of ICP was tested through Enzyme-linked Immunosorbent Assay and found significantly variable (P < 0.01) between and within accessions. The highest mean expression was observed in Accession-2 and Accession-4, while the lowest in Accession-21 and Accession-19. Among fresh leaf tissues from different parts of the plant, the highest mean expression was recorded at 60 days after sowing in upper canopy leaves of cotton accessions, which decreased in lower parts of the plant with the lowest mean expression in lower canopy leaves. Laboratory bioassays, to calculate lethal dose, for H. armigera showed that LD50 and LD95 were 0.62 µg/g and 1.59 µg/g of fresh tissue weight, respectively. A strong positive correlation also exists between the levels of Cry1Ac protein and insect mortality (r = 0.84). These findings suggested the future risk of cultivation of Bt cotton, carrying single Cry1Ac gene, in Pakistan, as resistance surging in H. armigera against Cry protein. These results may also have significant implications for the resistance management in Bt crops, especially cotton, in future.

Comparative analysis of resistance gene analogues encoding NBS-LRR domains in cotton.

BACKGROUND: Plant production is severely affected by biotic and abiotic stresses R-genes exhibit resistance against a range of diseases and pathogens in plants. The nucleotide binding site and leucine rich repeat (NBS-LRR) class of R-genes is the most comprehensively studied in terms of sequence evolution and genome distribution. The differential response for resistance against biotic and abiotic stress has been observed in cultivated and wild relatives of the genus Gossypium. RESULTS: Efforts have been made to address the recent evolution of NBS-LRR sequences within Gossypium hirsutum and resistance gene analogue (RGA) sequences derived from G. arboreum and G. raimondii. The % identity and phylogenetic analysis of NBS-LRR-encoded RGAs from tetraploid New World cotton and its diploid ancestors G. raimondii and G. arboreum suggest that the evolution of NBS-LRR-encoding sequences in G. hirsutum occurred by gradual accumulation of mutants that led to positive selection and a slow rate of divergence within distinct R-gene families. CONCLUSION: The allotetraploid genome of cotton, after separating from its diploid parents, experienced polyploidisation, natural and artificial selection, hybrid necrosis, duplication and recombination which became the reason to shed off and evolve new genes for its survival. These driving forces influenced the development of genomic architecture that make it susceptible to diseases and pathogens as compared to donor parents.

Identification and characterization of plasma membrane aquaporins isolated from fiber cells of Calotropis procera.

Calotropis procera, commonly known as "milkweed", possesses long seed trichomes for seed dispersal and has the ability to survive under harsh conditions such as drought and salinity. Aquaporins are water channel proteins expressed in all land plants, divided into five subfamilies plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like proteins (NIPs), small basic intrinsic proteins (SIPs), and the unfamiliar X intrinsic proteins (XIPs). PIPs constitute the largest group of water channel proteins that are involved in different developmental and regulatory mechanisms including water permeability, cell elongation, and stomata opening. Aquaporins are also involved in abiotic stress tolerance and cell expansion mechanisms, but their role in seed trichomes (fiber cells) has never been investigated. A large number of clones isolated from C. procera fiber cDNA library showed sequence homology to PIPs. Both expressed sequence tags (ESTs) and real-time polymerase chain reaction (PCR) studies revealed that the transcript abundance of this gene family in fiber cells of C. procera is greater than that of cotton. Full-length cDNAs of CpPIP1 and CpPIP2 were isolated from C. procera fiber cDNA library and used for constructing plant expression vectors under constitutive (2×35S) and trichome-specific (GhLTP3) promoters. Transgenic tobacco plants were developed via Agrobacterium-mediated transformation. The phenotypic characteristics of the plants were observed after confirming the integration of transgene in plants. It was observed that CpPIP2 expression cassette under 2×35S and GhLTP3 promoter enhanced the numbers of stem and leave trichomes. However, 2×35S::CpPIP2 has a more amplified effect on trichome density and length than GhLTP3::CpPIP2 and other PIP constructs. These findings imply the role of C. procera PIP aquaporins in fiber cell elongation. The PIPs-derived cell expansion mechanism may be exploited through transgenic approaches for improvement of fiber staple length in cotton and boosting of defense against sucking insects by enhancing plant pubescence.

Extraction of DNA suitable for PCR applications from mature leaves of Mangifera indica L.

Good quality deoxyribonucleic acid (DNA) is the pre-requisite for its downstream applications. The presence of high concentrations of polysaccharides, polyphenols, proteins, and other secondary metabolites in mango leaves poses problem in getting good quality DNA fit for polymerase chain reaction (PCR) applications. The problem is exacerbated when DNA is extracted from mature mango leaves. A reliable and modified protocol based on the cetyltrimethylammonium bromide (CTAB) method for DNA extraction from mature mango leaves is described here. High concentrations of inert salt were used to remove polysaccharides; Polyvinylpyrrolidone (PVP) and ß-mercaptoethanol were employed to manage phenolic compounds. Extended chloroform-isoamyl alcohol treatment followed by RNase treatment yielded 950-1050 µg of good quality DNA, free of protein and RNA. The problems of DNA degradation, contamination, and low yield due to irreversible binding of phenolic compounds and coprecipitation of polysaccharides with DNA were avoided by this method. The DNA isolated by the modified method showed good PCR amplification using simple sequence repeat (SSR) primers. This modified protocol can also be used to extract DNA from other woody plants having similar problems.