Genetics & Plant Breeding - ICAR JRF/SRF 2024

• Haploid Chromosome Numbers ($n$) in Major Field Crops:
• Hordeum vulgare (Barley): Diploid species with $2n = 2x = 14$; haploid chromosome number is $n = 7$ $\rightarrow$ (II)
• Chickpea (Cicer arietinum): Diploid pulse with $2n = 2x = 16$; haploid chromosome number is $n = 8$ $\rightarrow$ (I)
• Sunflower (Helianthus annuus): Diploid oilseed with $2n = 2x = 34$; haploid chromosome number is $n = 17$ $\rightarrow$ (IV)
• Rice (Oryza sativa): Diploid cereal with $2n = 2x = 24$; haploid chromosome number is $n = 12$ $\rightarrow$ (III)
• Systematic Match: (A)-(II), (B)-(I), (C)-(IV), (D)-(III) corresponds to Option 3.

Correct option: (3) (A) - (II), (B) - (1), (C) - (IV), (D) - (ttl)

• Harlan and de Wet's Gene Pool Concept (1971):
• Statement I is Correct: The Primary Gene Pool ($GP-1$) encompasses the cultivated species, primitive landraces, and freely crossable wild/weedy conspecific taxa. Crosses produce vigorous, completely fertile hybrids with normal chromosome pairing and gene recombination.
• Statement II is Correct: The Secondary Gene Pool ($GP-2$) consists of related, co-generic species that can cross with cultivated species to produce hybrids; however, hybrids typically exhibit reduced fertility, chromosome structural differences, and partial meiotic sterility.
• Statement III is Incorrect: The Tertiary Gene Pool ($GP-3$) consists of distant wild species where conventional crossing produces lethal, non-viable, or completely sterile hybrids. Gene transfer is not naturally crossable and requires advanced biotechnological intervention (such as embryo rescue, tissue culture, bridging species, or somatic protoplast fusion).
• Conclusion: Statements I and II are correct, Statement III is incorrect (Option 2).

• Diversity Arrays Technology (DArT): A sequence-independent microarray hybridization genotyping platform developed by Jaccoud et al. (2001).
• Complexity Reduction: Uses restriction enzymes (such as PstI and TaqI) followed by adaptor ligation and PCR amplification to generate genomic representations, a complexity reduction procedure derived from and essentially similar to AFLP methodology. (Correct answer: Option 1)