Expression dynamics of S locus genes defining self-incompatibility in tetraploid potato (Solanum tuberosum L.) Cv. Kufri Girdhari

Gametophytic self-incompatibility (SI) controlled by the multiallelic S-locus, that include tightly linked SRNase and SLF genes has been reported extensively in wild and diploid potatoes. The widely cultivated tetraploid are reported to overcome SI through a phenomenon called ‘competition interaction’ or ‘heteroallelic pollen’ effect. Here we report the activated Gametophytic SI in a tetraploid, non-fruiting popular Indian cultivar Kufri Girdhari through pollen and gene expressional studies. The results revealed highly stage-specific expression of S-RNase in contrast to ubiquitous SLFs in flower. Our preliminary studies found that S-RNase expressed in flower stigma and style after the pollination provide the evidence for the general mechanism SI. The recombination event and later fixing of the genetic composition may have lead to homomorphic condition that causes SI in the variety despite being a tetraploid. The study reveals the functional SI system acting in a tetraploid first time and further in-depth investigation of allele composition would provide complete understanding that would help in designing the future breeding programs.