Exploring altitude-driven diversity: morphological, biochemical, and genetic diversity analysis of Khasi mandarin (Citrus reticulata Blanco) in Meghalaya, India

Khasi Mandarin (Citrus reticulata Blanco) is one of the most extensively cultivated and commercially important fruit crop of Northeast India, and it is widely used for culinary purposes due to its fragrance and unique taste. This study investigated the genetic variability of elite Khasi mandarin plants from diverse altitudes in the northeastern state of Meghalaya, India. Morphological, biochemical and molecular analyses were conducted on fruits collected from nine locations spanning various altitudes. Significant variation was observed in tree morphology, fruit characteristics, and biochemical composition. Higher altitudes were associated with distinct fruit quality traits, such as higher total soluble solids (TSS), titratable acidity, sugar and ascorbic acid content, with correlation research showing that higher altitudes generally corresponded to better overall fruit quality parameters. This study provides insights for optimizing fruit production across altitudinal gradients. Eleven out of 40 simple sequence repeat markers used for genetic diversity analysis exhibited polymorphism. Cluster analysis grouped genotypes by altitude, and the analysis of molecular variance (AMOVA) confirmed significant genetic distinctions between populations (74%). Positive correlations were observed between genetic and geographical distances (r = 0.230) and between genetic distances based on molecular and morphological data (r = 0.506). These insights are crucial for future conservation and crop improvement efforts.