transcription machinery used (Column II) and target tissue type (Column III)
to express a foreign gene in a plant system.

• (A) P-1-i, Q-3-ii, R-2-i, S-3-ii
• (B) P-3-i, Q-1-i, R-2-ii, S-1-ii
• (C) P-2-i, Q-2-ii, R-1-i, S-2-i
• (D) P-1-ii, Q-3-i, R-2-ii, S-3-ii
  

  Key Concepts Required

  To express a foreign gene in plants, three things must match correctly:

  1. Promoter type → determines where and when gene is expressed

  2. Transcription machinery → nucleus vs organelles

  3. Target tissue → leaf-specific or seed-specific

  ---

  Step-by-Step Matching

  ---

  P. Ubiquitin promoter

  • Constitutive promoter

  • Expressed in most tissues

  • Transcribed by nuclear machinery

  • Often used in leaf tissues

  Match: P → 2 (Nucleus), i (Leaf)

  ---

  Q. Napin promoter

  • Seed-specific promoter

  • Used for storage proteins

  • Transcribed in the nucleus

  Match: Q → 2 (Nucleus), ii (Seed)

  ---

  R. RbcL promoter

  • Codes for large subunit of RuBisCO

  • Gene is present in the chloroplast genome

  • Expressed in leaf tissue

  • Uses chloroplast transcription machinery

  Match: R → 1 (Chloroplast), i (Leaf)

  ---

  S. RbcS promoter

  • Codes for small subunit of RuBisCO

  • Gene is nuclear-encoded

  • Protein is transported to chloroplast

  • Expressed in leaf tissue

  • Uses nuclear transcription machinery

  Match: S → 2 (Nucleus), i (Leaf)

  ---

  Correct Combination

  P ⁣− ⁣2 ⁣− ⁣i,  Q ⁣− ⁣2 ⁣− ⁣ii,  R ⁣− ⁣1 ⁣− ⁣i,  S ⁣− ⁣2 ⁣− ⁣i\boxed{P\!-\!2\!-\!i,\; Q\!-\!2\!-\!ii,\; R\!-\!1\!-\!i,\; S\!-\!2\!-\!i}P−2−i,Q−2−ii,R−1−i,S−2−i​

  ---

  Correct Option

  Option (C)\boxed{\textbf{Option (C)}}Option (C)​

  ---

  Why Other Options Are Incorrect

  Option (A) ❌

  • Assigns ubiquitin to chloroplast → incorrect

  • Ubiquitin is a nuclear promoter

  ---

  Option (B) ❌

  • Places RbcL under nuclear machinery → incorrect

  • RbcL is chloroplast-encoded

  ---

  Option (D) ❌

  • Assigns Napin to mitochondria → incorrect

  • Napin is nuclear, seed-specific

  ---

  SEO-Friendly Introduction

  Understanding promoter transcription machinery tissue specificity in plants is a fundamental concept in plant biotechnology and molecular biology. Questions based on promoter selection are frequently asked in CSIR-NET, GATE, IIT-JAM, and JAM examinations, especially in the context of transgenic plant development.

  ---

  Why Promoter Choice Matters in Plant Genetic Engineering

  • Determines where the gene is expressed

  • Controls tissue specificity

  • Dictates which transcription machinery is used

  • Critical for stable and efficient transgene expression

  ---

  Quick Memory Tricks for Exams

  📌 Napin → Seed
  📌 Ubiquitin → Constitutive / Leaf
  📌 RbcL → Chloroplast genome
  📌 RbcS → Nuclear gene, leaf expression

  ---

  Final Conclusion

  ✔ Ubiquitin and Napin are nuclear promoters
  ✔ RbcL is chloroplast-encoded
  ✔ RbcS is nuclear-encoded but leaf-specific
  ✔ Correct promoter–machinery–tissue match is:
  option: