A Rice chitinase-3 under enhance version of CaMV 35S was introduced into peanut (Arachis hypogaea L.) through Agrobacterium mediation. Agrobacterium tumefaciens strain LB4404 was used harboring the binary vector (pB1333-EN4-RCG3) containing the chitinase (chit) and hygromycin resistance (hpt) gene as selectable marker. Putative transgenic shoots were regenerated and grown on MS medium supplemented with 5 mg/l BAP, 1 mg/l kinetin, and 30 mg/l hygromycin. Elongated shoots were examined for the presence of the integrated rice chitinase gene along with hygromycin gene as selectable. The integration pattern of transgene in the nuclear genome of the putative transformed plants (T(0)) was confirmed through Southern hybridization analysis of the genomic DNA. Survival rate of the in vitro regenerated plantlets was over 60% while healthy putatively transgenic (T(0)) plants with over 42% transformation frequency were produced through Agrobacterium mediated gene transfer of the rice chitinase gene and all the plants flowered and set seed normally. T1 plants were tested for resistance against Cercospora arachidicola by infection with the microspores. Transgenic strains exhibited a higher resistance than the control (non-transgenic plants). chitinase gene expression in highly resistant transgenic strains was compared to that of a susceptible control. A good correlation was observed between chitinase activity and fungal pathogen resistance.
A nutrient solution experiment was conducted to determine the influence of N forms on growth, oxidative stress, and Cd and N uptake in rice plants. The treatments were consisted of two Cd levels (0 and 1 lmol) and three N forms (NH 4 ) 2 SO 4 , NH 4 NO 3 and Ca(NO 3 ) 2 . The results indicated that without Cd addition in the culture solution, the N forms had no significant effect on all measured parameters, including plant growth, photosynthetic traits, malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and Cd and N concentration, while Cd addition in the medium resulted in significant differences in measured parameters among the three forms of N fertilizers. The least inhibition of growth was noted in (NH 4 ) 2 SO 4 -fed plants, and the largest in Ca(NO 3 ) 2 -fed plants, when plants were exposed to Cd stress. The highest photosynthetic rate and chlorophyll content was also recorded in (NH 4 ) 2 SO 4 -fed plants. Addition of Cd caused a remarkable increase in SOD activity and MDA content in plants, and the extent of increase varied with N form, with (NH 4 ) 2 SO 4 -fed plants being smallest. In comparison with the control plants, the N concentration in roots and shoots was not significantly affected in (NH 4 ) 2 SO 4 -fed plants, but significant decrease in root N concentration was found for the NH 4 NO 3 and Ca(NO 3 ) 2 -fed plants under Cd stress. Moreover, the significant differences were also noted among the three N forms in both root and shoot Cd concentrations, with (NH 4 ) 2 SO 4 -fed plants being the lowest. The results indicated that the toxic effect of Cd on rice varied with the form of N fertilizer.
Cold is a major constraint for tomato growth and productivity; as it is a cold sensitive crop. DREB1A plays a key role in generating cold tolerance in tomato by regulating the response of multiple genes under chilling stress. In this study, cold tolerant gene (DREB1A) driven by Lip9 promoter, was transformed in three tomato genotypes through Agrobacterium tumefaciens, employing tissue culture independent transformation strategy. Overnight imbibed seeds of tomato were surface sterilized, 3-day old shoot apical meristem of the developing seedling were pierced and incubated for twenty minutes with A. tumefaciens strain EHA-105 having OD 600 nm of 1.0. The treated seeds were co-cultivated with Agrobacterium for 2 days. The regenerated shoots were subjected to 35 mg/l hygromycin as a selection for a period of 2-3 weeks. The presence of DREB1A and hpt genes in the hygromycin resistant (T 0 ) transgenic plants was evaluated by PCR analysis. The transgene activity was detected in T 1 plants by Reverse Transcriptase Polymerase Chain Reaction and Southern blotting that showed the stable integration of the transgene to the next generation. Physiological analysis of T 2 transgenic plants depicted that increased expression of DREB1A induced only during chilling stress. After various chilling stresses, stomatal conductance, transpiration rate and relative water contents of transgenic lines were significantly higher than those of NT plants. While leaf osmotic potential of transgenic plants was lower as compared to NT plants. The established procedure is novel and can produce stable transgenic tomato plants in efficient manner by saving potential resources in terms of cost and time.
Genetically modified, insect-resistant Bacillus thuringiensis (Bt) cotton is cultivated extensively in Pakistan. Past studies, however, have raised concerns about the prevalence of Bt cotton varieties possessing weak or nonperforming insect-resistance traits conferred by the cry gene. We examine this issue using data drawn from a representative sample of cotton-growing households that were surveyed in six agroclimatic zones spanning 28 districts in Pakistan in 2013, as well as measurements of Cry protein levels in cotton tissue samples collected from the sampled households’ main fields. The resultant dataset combines information from 593 sampled households with corresponding plant tissue diagnostics from 70 days after sowing, as well as information from 589 sampled households with corresponding diagnostics from 120 days after sowing. Our analysis indicates that 11 percent of farmers believed they were cultivating Bt cotton when, in fact, the Cry toxin was not present in the tested tissue at 70 days after sowing (i.e., a Type I error). The analysis further indicates that 5 percent of farmers believed they were cultivating non-Bt cotton when, in fact, the Cry toxin was present in the tested tissue (i.e., a Type II error). In addition, 17 percent of all sampled farmers were uncertain whether or not they were cultivating Bt cotton. Overall, 33 percent of farmers either did not know or were mistaken in their beliefs about the presence of the cry gene in the cotton they cultivated. Results also indicate that toxic protein levels in the plant tissue samples occurred below threshold levels for lethality in a significant percentage of cases, although these measurements may also be affected by factors related to tissue sample collection, handling, storage, and testing procedures. Nonetheless, results strongly suggest wide variability both in farmers’ beliefs and in gene expression. Such variability has implications for policy and regulation in Pakistan’s transgenic cotton seed market.
Peanut (Arachis hypogaea) is an important legume and oilseed crop,
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