Genetic diversity at MHC-DRB3 locus suggests distinctness of the riverine-swamp buffalo populations in North-East region of India

Abstract

Northeast region of India is a transition zone for two genetically distinct types of water buffalo (Bubalus bubalis) - riverine (Bubalus bubalis bubalis, N=50) and swamp (Bubalus bubalis carabanesis, N=48), wherein, both types of buffalo populations and their hybrids (riverineswamp, N=49) coexist. In present study, we studied genetic variability of highly polymorphic major histocompatibility complex (MHC) class II- DRB3 gene in 94 riverine-swamp buffaloes of three different locations - central Assam (ASW; riverine and hybrid types), Silchar region (ASW-SL, swamp and hybrid types), Dibrugarh region (ASW-DB, swamp) of Assam through PCR-RFLP. A total of nine HaeIII restriction patterns HaeIII- A to I, were observed in overall populations, although only six patterns were present in ASW-DB buffaloes. The HaeIII-A, -C, -F and -H patterns were found to be homozygous, accounting about 48 percent of the total buffalo population. Based on DRB3-HaeIII restriction diversity, the genetic divergence was the highest (0.460) between ASW-SL and ASW-DB buffaloes whereas, the lowest (0.063) between ASW and ASW-DB buffaloes among three populations. In Principle Coordinate Analysis (PCA), these populations were found to be distantly located in different coordinates, indicating their genetic distinctness. Our results support that North-east region of India constitute a transition zone for both riverine and swamp buffalo populations, however, with quite distinctness of these mixed populations derived through different genetic pools. Polymorphic DRB3 locus in these riverine-swamp buffalo populations of North-East region also indicates their genetic richness.