Following are a few statements regarding mapping populations and principles of genetic mapping in crop species.
A. For self-pollinating species, both F2 and F1-derived doubled haploids can serve as mapping populations.
B. For cross-pollinating species, F1 population can be used for mapping studies.
C. Bulk segregant analysis (BSA) is often used to identify linked markers for complex traits with multiple genes and environmental influences.
D. In crop plants, sets of different breeding lines can be exploited for trait mapping.
E. Breeding methods such as single-seed descent and pedigree selection promote genetic variability.
Which one of the following options represents the combination of all INCORRECT statements?

Correct option is D

Correct answer

Option 4 — C and E only

Explanation

Evaluate each statement for correctness:

A — Correct. In self-pollinating species F2 populations are widely used for mapping; F1-derived doubled haploids (DH) provide fully homozygous lines that are also excellent mapping populations.

B — Correct. For many cross-pollinating species, F1 (or F1 families/full-sib families) can be used in mapping approaches (e.g., pseudo-testcross mapping), so F1 populations are usable for mapping.

C — Incorrect. Bulk segregant analysis (BSA) is most effective for traits controlled by a major gene or a few major QTL with clear phenotypic classes; it is not well suited to highly polygenic, environmentally influenced complex traits.

D — Correct. Sets of different breeding lines (diversity panels, elite lines) are exploited in association mapping/GWAS to map traits.

E — Incorrect. Methods like single-seed descent (SSD) and pedigree selection do not promote genetic variability — SSD fixes alleles rapidly by advancing inbreeding generations, and pedigree selection applies selection that tends to reduce variability in the chosen population.

Thus the combination of all incorrect statements is C and E, i.e., Option 4.