Abstract
Onion is one of the most widely cultivated high-value vegetables on the globe. The study of variability and genetic divergence in this crop will facilitate judicious parent selection for future breeding. The present study incorporated 20 onion genotypes to determine the genetic variability and diversity through morpho-physiological and molecular markers. The genotypes were tested for two consecutive years to determine the effects on yield-attributing and bulb-quality traits. Diversity at a molecular level with 31 simple sequence repeat (SSR) markers was determined. Adequate genetic variability existed among the genotypes, with a predominance of additive gene action regarding the inheritance of most of the characteristics. Principal component (PC) analysis detected seven PCs contributing to more than 87% of the genetic diversity in the genotypes. Total yield (kg/plot), Grade ‘C’ bulb (equatorial diameter of the bulb between 3.5 and 4.5 cm), individual bulb weight (g) and phenol content were detected as characteristics positively associated with the first two PCs. A total of 16 primers were amplified, and they produced 32 alleles in the genotypes. Genetic diversity at the morphological and molecular levels indicated moderate diversity among the tested genotypes, with the dissolution of the genotypes into six and three clusters, respectively. The present study on onion facilitates the selection of diverse parents that can generate desirable segregants in future breeding programmes.
Highlights
Introduction conditions of the Creative CommonsOnion (Allium cepa L.), belonging to the family Alliaceae, is an important high-value bulbous vegetable crop cultivated globally [1]
Genomic DNA was isolated through CTAB DNA extraction protocol [19] from twoweek-old leaf tissue of individual plants from 20 onion genotypes grown in the field
Combined analysis of variance over the period of 2 years revealed a significantly higher amount of variability among the genotypes for all the yield-attributing and bulb-quality traits studied, which affirmed the presence of significant genetic variation among the onion genotypes (Table 1)
Summary
Onion (Allium cepa L.), belonging to the family Alliaceae, is an important high-value bulbous vegetable crop cultivated globally [1]. Morphological markers are meagre in number, as well as being highly influenced by environmental factors, and they are sometimes not able to differentiate between closely related individuals [9]. From this perspective, the utilisation of molecular markers has been successfully proven towards manoeuvring the problems associated with either morphological or biochemical markers. The present investigation was outlined with the following objectives: appraisal of the genetic variability of the onion genotypes based on yield-attributing and qualitative traits and assessment of the level of genetic diversity among the tested onion genotypes using morphological and molecular markers
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