During backcrossing, which backcross generation represents 99.8 percent genes of the recurrent parent? (RJ AARO Botany 2018)

✅ Explanation: In backcrossing, a hybrid is repeatedly crossed with one of its parents to recover the desired traits from that parent. Each successive backcross generation increases the proportion of genes from the recurrent parent.
Typically, after around 8-10 backcross generations, the progeny will have approximately 99.8% of the genes from the recurrent parent. Therefore, in this case, the BC8 generation would be expected to have around 99.8% of the genes from the recurrent parent.

📌Other Options Explanations:
-Option A: BC7: While BC7 might have a high proportion of genes from the recurrent parent, it is generally not as close to 99.8% as BC8.
-Option C: BC9: BC9 would likely have an even higher proportion of genes from the recurrent parent than BC8.
-Option D: BC10: Similar to BC9, BC10 would probably have an even higher percentage of genes from the recurrent parent.

🔑Key Points: Recombinant Inbred Lines (RILs):
-Immortality: RILs are created by successive generations of self-fertilization (inbreeding) from a single heterozygous individual. Once established, RILs are considered immortal because they can be maintained by selfing indefinitely. Each line is essentially a set of homozygous individuals derived from the same original heterozygous plant.

• Doubled Haploids:
-Immortality: Doubled haploids are created by doubling the chromosome number of haploid cells, typically through chromosome doubling techniques. These plants are homozygous for all loci. While the process of creating doubled haploids might involve mortality (e.g., from tissue culture manipulations), the resulting plants themselves can be maintained indefinitely by selfing.

• F2:3 Population:
-Mortality: F2:3 populations are created by selfing F2 individuals. Each F2 individual carries a unique combination of alleles from the F1 generation. However, as F2:3 populations are generated through selfing, they are not immortal because, over generations, genetic variation is lost due to segregation and recombination.

• Near Isogenic Lines (NILs):
-Immortality: NILs are created by backcrossing a selected genotype (donor parent) to a recurrent parent followed by several generations of selfing. The resulting lines are genetically similar to the recurrent parent except for the specific genomic region introgressed from the donor parent. Once established, NILs can be maintained by selfing, making them immortal