CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats - Cas9 endonuclease) uses a synthetic single-guide RNA (sgRNA) to target a specific complementary 20-nucleotide genomic site and introduce a precise double-stranded break (DSB).
It enables highly precise targeted modifications including gene knockout (via non-homologous end joining NHEJ) as well as targeted base substitutions and gene insertion/editing (via homology-directed repair HDR).
Unlike classical transgenics (GMOs), targeted editing under SDN-1 and SDN-2 categories introduces non-transgenic, transgene-free edits without leaving foreign DNA in the crop genome.

The somatic chromosome numbers ($2n$) of the four crops are:

• Pigeon pea (Cajanus cajan): $2n = 22$ (diploid, $x = 11$)
• Rice (Oryza sativa): $2n = 24$ (diploid, $x = 12$)
• Groundnut (Arachis hypogaea): $2n = 4x = 40$ (allotetraploid, $x = 10$)
• Bread Wheat (Triticum aestivum): $2n = 6x = 42$ (allohexaploid, $x = 7$)
  
  Arranging in ascending numerical order:
  $$22\text{ (Pigeon pea)} \lt 24\text{ (Rice)} \lt 40\text{ (Groundnut)} \lt 42\text{ (Wheat)}$$

In the standard universal genetic code:
The universal start (initiator) codon is $5'\text{-AUG-}3'$.
It serves a dual role: (1) It signals the initiation of translation at the ribosome, and (2) It specifies the sulfur-containing amino acid Methionine (Met in eukaryotes, $N$-formylmethionine / fMet in prokaryotes and plastids).
Stop codons are $UAA$ (ochre), $UAG$ (amber), and $UGA$ (opal), none of which function as start codons.