Molecular cloning and quantitative real-time PCR analysis to study the expression of tryptophan decarboxylase gene from chillies (Capsicum annuum L.) against whitefly

Background: One of the amazing and economical spices is Chilli (Capsicum annum L.) and also called “wonder spice,” and it gives great significance to traditional household use and export as well as such a remarkable cash crop in India. However, the important constraints in chilli production are chilli leaf curl disease which has been caused by whitefly (Bemisia tabaci) transmitted by begomoviruses and leads to a major decline in yield. Aim: To explore the stability of the insect resistance gene (tryptophan decarboxylase [TDC]) in resistant genotypes after being challenged with a known number of whiteflies. Since, biotic stress defense allied mechanism regulated during tryptophan biosynthesis. Materials and Methods: The presence of endogenous genes was verified using the polymerase chain reaction (PCR), cloning (T/A vector), and gene expression level (quantitative real-time PCR). Results: Amplification of mitochondrial coxI gene fragment using the primer (C1-J-2195 and L2-N-3014) produced B. tabaci specific ~ 800 bp band. Besides, the whitefly sequence was aligned with the NCBI blast where 92% of identity was observed. TDC gene expression was greater in P2 accession leaves at 48 h post-infestation with 20 number of B. tabaci after feeding and downregulation in less TDC gene expression level at moderately resistant accession ACC 20. Further, all the amplified gene sequences were aligned using NCBI BLAST. The expression of TDC genes in chillies could demoralize the B. tabaci fitness causes mortality. Conclusion: The satisfactory control of viral disease may be achieved with the application of molecular biology, DNA, and RNA-based technologies include the cloning of insect resistance genes.