Citrus genetic resources in Meghalaya, a home of national Citrus gene sanctuary: Collection, morphological characterization and its implications on conservation

Abstract Genus Citrus L. (Family: Rutaceae ), thrives best in tropical/sub-tropical climates, finds a perfect ecosystem in Meghalaya (home for National Citrus Gene Sanctuary), a North-Eastern Indian State. This state harbors rich diversity of Citrus species; however, they are under severe threat due to anthropogenic activities. Hence, present study was undertaken during 2021–22 to explore, collect, characterize and document Citrus species diversity for their conservation and posterity use. Total of 57 accessions belonging to 13 different Citrus species were collected and 48 traits (16 quantitative and 32 qualitative) were recorded for each accession, using IPGRI descriptors (1999). Garo and Khasi hills are hotspots for Citrus diversity, harboring a significant number of citrus species. Notably, South Garo Hills and West Khasi Hills emerged as critical regions for the conservation of wild Citrus species, particularly C. indica in South Garo Hills. Most species exhibited large leaf length (>75 mm), whereas, wild species C. latipes had smaller leaves (29.7 mm). Cluster analysis formed the dendrogram by using jaccard’s similarity index based UPGMA method with six clusters and showed higher levels of complexity between Citrus species at inter and intra-cluster levels. PCA analysis explained about 73.3% cumulative genetic variation present among them and the first three PCs as 37.7, 20.5 and 15.1%, respectively. Fruit-related traits (size, shape, colour, apex shape, surface texture, rind thickness, axis, pulp colour and firmness) were identified as diagnostic character for distinguishing different Citrus species or major Citrus fruit groups and also useful for field identification during exploration trips and curators in Genebank management.