Intraspecific karyotypic diversity: A case study of Zea mays L. from Pir Panjal Himalaya

Abstract

Maize is an important food crop for humans, as well as a key component of animal feed and raw material for a variety of industrial products. In the present investigation, ten cultivars of maize (Zea mays L.) grown across the Rajouri region of Pir Panjal Himalaya were karyomorphologically characterized. All these cultivars possessed the same chromosome number (2n = 2x = 20). Although the number of chromosomes was the same in all the cultivars, diversity in size and structure was noticed. Cultivars 1, 2, 5, and 8 had the most symmetrical karyotype, falling in the 3A category, while cultivars 7 and 4, and 6 fall in the 3B and 4B categories, respectively. Analysis of karyotypes suggested that cultivar 6 is highly evolving, followed by cultivars 4 and 7. On resolving chromosome complements of all the studied cultivars into metacentric, median, submetacentric, and subtelomeric, different karyotypic formulae were devised, revealing variability of the genome and chromosomal alterations among cultivars. Cluster analysis based on karyotypic data grouped ten cultivars into three major groups. Cultivars 9, 2, 8, and 4 forms one group; cultivars 10, 7, 6, and 5 form the second group, whereas cultivars 3 and 1 constitute the third group. Principal coordinate analysis also revealed the existence of diversity among the investigated maize cultivars. The karyotypic variation detected in the present investigation can be utilized for germplasm conservation and breeding purposes of maize.