Presence of integrase core domain in mutant type black pepper Piper nigrum L. ‘Thekken’ with altered inflorescence architecture

ABSTRACT

Black pepper (Piper nigrum L.), referred as the ‘King of Spices’, is native to India and has shown declined productivity over the years. It exhibits diverse quantitative and qualitative traits, particularly in spike length, floral composition, floral arrangement, fruit size and number. The novel mutant variety of black pepper (Piper nigrum L.) ‘Thekken’ shows a remarkable branching character in the spikes. In the present study, we analyzed RAMOSA3 (RA3) gene at the molecular level in this variety for yield improvement. Screening using degenerate primers designed for RA3 was carried out in ‘Thekken’ and a non-branching variety ‘Karimunda’ at the genomic level and at different stages of spike development at the transcriptome level. Sequence analysis of the amplicons generated in RT-PCR revealed the presence of an integrase core domain in the mutant type of black pepper, suggesting a possibility of mutation at this locus in the branched variety due to retrotransposon integration. The study suggests a possibility for introgression of the genes responsible for branching trait from the mutant variety of black pepper type ‘Thekken’ to other conventional cultivated varieties of black pepper that show single unbranched spike thereby increasing the productivity of black pepper which has very high economic value and export potential.