Given below are a few statements about plant breeding and transgenesis: A. Recombinant inbred lines and double haploid populations have high levels of genetic homozygosity. B. Gene pyramiding involves introducing different genes for resistance to a specific pest in different genotypes of a plant species. C. Agrobacterium strains with a disarmed Ti plasmid do not require vir genes for transfer of T‐DNA. D. Molecular breeding can be used for crop improvement if the trait of interest is present in naturally occurring populations of the plant. Which one of the following options represents a combination of INCORRECT statements?
B and C
Plant Breeding and Transgenesis Statements Analysis
Let's analyze each statement provided regarding plant breeding and transgenesis to determine which ones are incorrect.
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Statement A: Recombinant inbred lines and double haploid populations have high levels of genetic homozygosity.
Analysis: Recombinant inbred lines (RILs) are developed through repeated selfing of progeny from a cross between two parental lines. This process leads to increased homozygosity over generations. Double haploids (DHs) are produced by chromosome doubling of haploid cells, resulting in individuals that are completely homozygous at all loci. Therefore, this statement is correct.
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Statement B: Gene pyramiding involves introducing different genes for resistance to a specific pest in different genotypes of a plant species.
Analysis: Gene pyramiding is a technique used to combine multiple desirable genes (often for resistance to one or more pests or diseases) from different sources into a single plant genotype. The goal is to stack these genes together within one improved variety or line, not to introduce them into different genotypes. Therefore, this statement is incorrect.
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Statement C: Agrobacterium strains with a disarmed Ti plasmid do not require vir genes for transfer of T‐DNA.
Analysis: A "disarmed" Ti plasmid has the tumor-inducing T-DNA region removed, but the vir (virulence) genes located on the plasmid (or on a helper plasmid) are absolutely essential for processing the T-DNA border sequences, excising the T-DNA (or the inserted DNA between the borders), and transferring it into the plant cell. Without the vir genes, T-DNA transfer cannot occur. Therefore, this statement is incorrect.
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Statement D: Molecular breeding can be used for crop improvement if the trait of interest is present in naturally occurring populations of the plant.
Analysis: Molecular breeding utilizes molecular markers to select for desirable traits. This is often applied to traits that exist within the gene pool of the crop species, including its wild relatives. Markers linked to genes controlling such traits can be used to speed up the selection process compared to traditional phenotypic selection. Therefore, this statement is correct.
Identifying Incorrect Statements
Based on the analysis:
- Statement A is Correct.
- Statement B is Incorrect.
- Statement C is Incorrect.
- Statement D is Correct.
We are looking for the combination of INCORRECT statements.
The incorrect statements are B and C.
Conclusion
The combination of incorrect statements is B and C.
Important Questions from Transgenic animals and plants
An experiment was performed to introduce a transgenic trait in a crop plant by Agrobacterium-mediated transformation using a transgene construct in which the transgene was expressed using the CaMV 35S promoter. It was observed that expression levels of the transgenic protein were very low in all transgenic plants while transgene mRNA levels were high and variable among different plants. Further, different transgenic lines contained different numbers of the T-DNA insert. The following statements were made to explain the above observation:
A. Variations in the number of T-DNA inserts in different transgenic plants is due to more number of host cells getting infected with the T-DNA
B. Low expression levels of the transgenic protein in all transgenic plants could be due to codon usage variations between the host plant and the heterologous source of the transgene
C. The coding sequence of the transgene contained sequences that destabilized the transgene mRNA
D. Variation in copy number of T-DNA in different transgenic plants is due to variation in the promoter used to express the transgene.
Which one of the following options represents all correct
statements?Following statements were given regarding factors influencing variation in expression levels of transgene in transgenic plants:
A. Difference in restriction enzyme sites within the T-DNA.
B. Difference in copy number of the transgene.
C. Variations in site of integration of the T-DNA within the plant genome.
D. Presence of multiple promoters within the T-DNA region.
Which one of the following options represents a combination of statements that would NOT lead to variations in transgene expression levels in transgenic plants generated using the same T-DNA/binary vector?
Which one of the following statements related to genetic transformation of plants is correct?
The following statements are made regarding developing a transgenic mouse:
A. The transgenic mouse thus born will be a homozygous transgenic animal and can be maintained by crossing with another transgenic animal.
B. The fertilized transgenic eggs are allowed to develop in vitro.
C. The desired gene is preferably microinjected in male pronucleus after sperm entry in oocyte.
D. For best efficiency, the desired gene is always microinjected in the male gametes and then they are allowed to fertilize the female gametes.
E. Blastocyst stage embryos are transferred to the uterus of hormonally prepared mother.
F. The fertilized eggs are collected from specific strain of mouse.
G. The female mouse of specific strain is superovulated, oocytes are collected and allowed to fertilize in vitro.
Choose the combination of statements arranged in the correct sequence for developing transgenic mouse.
Which one of the following genomes is most appropriate to determine hybrids in plants and animals?
