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Plant Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Reverse breeding and doubled haploids (DH) is the most efficient method to produce homozygous plants from a heterozygous starting plant, which have all desirable traits. This starting plant is induced to produce DH from haploid cells, and later to create homozygous/DH plants of those cells. Although in natural offspring recombination occurs and traits can be unlinked from each other, in DH cells and in the resulting DH plants, recombination is no longer an issue. Here, a recombination between two corresponding chromosomes does not lead to un-linkage of alleles or traits, because it just leads to recombination with its identical copy. Thus, traits on one chromosome stay linked. Selecting those offspring that have the desired set of chromosomes and crossing them will result in a final F1 hybrid plant having the same set of chromosomes, genes, and traits as the starting hybrid plant. The homozygous parental lines can reconstitute the original heterozygous plant by crossing, if desired even in a large quantity. An individual heterozygous plant can be converted into a heterozygous variety (F1 hybrid) without the necessity of vegetative propagation, but as the result of the cross of two homozygous/DH lines derived from the originally selected plant.
Agricultural biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
Reverse breeding and doubled haploids (DHs) is the most efficient method to produce homozygous plants from a heterozygous starting plant, which has all desirable traits. This starting plant is induced to produce DH from haploid cells and later on to create homozygous/DH plants of those cells. While in natural offspring recombination occurs and traits can be unlinked from each other, in DH cells and in the resulting DH plants, recombination is no longer an issue. Here, a recombination between two corresponding chromosomes does not lead to unlinkage of alleles or traits, since it just leads to recombination with its identical copy. Thus, traits on one chromosome stay linked. Selecting those offspring that have the desired set of chromosomes and crossing them will result in a final F1 hybrid plant having exactly the same set of chromosomes, genes, and traits as the starting hybrid plant. The homozygous parental lines can reconstitute the original heterozygous plant by crossing, if desired even in a large quantity. An individual heterozygous plant can be converted into a heterozygous variety (F1 hybrid) without the necessity of vegetative propagation, but as the result of the cross of two homozygous/DH lines derived from the originally selected plant.
Grafting of watermelon (Citrullus lanatus cv. Mahbubi) onto different squash rootstocks as a means to minimize cadmium toxicity
Published in International Journal of Phytoremediation, 2018
Siamak Shirani Bidabadi, Reza Abolghasemi, Si-Jun Zheng
When both cotyledons and first true leaf started to develop, the growing point of rootstocks was removed and then a hole was created on the upper portion of the rootstock hypocotyls. The scions were then cut on a 45° angle from both sides, on the hypocotyls. The scions were then inserted into the hole made in the rootstocks.. Three grafting treatments were as follows: nongrafted Mahbubi (G1), Mahbubi grafted onto Cucurbita pepo Tiana F1 hybrid (G2) and Mahbubi grafted onto Cucurbita maxima (G3). The grafted plants were transplanted to plastic pots (25 cm in diameter) containing the same substrate as described above, with each pot containing one watermelon seedling. Nongrafted watermelons were used as a control. “Mahbubi” was selected as a representative watermelon cultivar that is cultivated in Iran. Grafted plants for 5 days were transferred to a healing at RH>95%, 29 °C and then, successfully grafted seedlings were allowed to grow for 4 weeks under constant temperature 25 ± 4 °C and 12 h of photoperiod. All plants were irrigated with full strength Hoagland nutrient solution (Hoagland and Arnon 1950) for two weeks (the pH of the nutrient solution was adjusted to 5.8). After 2 weeks of grafting cadmium stress was induced by supplementing Hoagland's solution with 0, 50, 100, and 200 μM CdCl2 and plants were irrigated after every 2 days. Pots receiving only Hoagland nutrient solution served as control. The amount of irrigation solution applied to each pot was 200 mL. Twenty days after treatments, grafted and nongrafted watermelons were used to measure leaf area, shoot and root dry weight, chlorophyll content, photosynthetic rate, electrolyte leakage, and antioxidant enzyme activities of the seedlings.
Towards a role-based authentication system based on SSVEP-P300 hybrid brain–computer interfacing
Published in Behaviour & Information Technology, 2022
Nikhil Rathi, Rajesh Singla, Sheela Tiwari
In any proposed security model, precision determines how accurately a particular class (target or non-target) has been predicted. Therefore, the proposed model achieves mean precision of 97.41%. Also, the current study achieves a mean F1-score equal to 97.51%. Further, these parameters are compared statistically for both paradigm conditions, and results indicate better performance of hybrid approach (PREhybrid > PREP300, p < .000071 and F1hybrid > F1P300, p < .000051).