ABSTRACT
BACKGROUND: Gaining insight into crop diversity, both at the genetic and phenotypic levels, is of prime importance for onion breeding with an enhanced yield and quality in combination with improved resistance to biotic and abiotic stresses. In the current study, 192 different onion plants, representing 16 ecotypes, were characterized using ISSR markers. RESULTS: Based on the ISSR marker profile, there was a clear grouping of the plants into 16 different ecotypes. Though the 16 populations originated from the same geographic region in Morocco, a significant genetic diversity was detected. After a genomic characterization, field trials in three different environments in Morocco were laid out. The phenotypic characterization showed that there were always significant differences between ecotypes, and for most traits, there was also a significant environmental effect and a significant interaction between environment and ecotype. The broad-sense heritability (H2) for the phenotypic traits associated with color (L*, a*, and b*) was the largest (84.2%, 80.6%, 79.2%), demonstrating that color is conditioned primarily by genetic factors. In contrast, the H2 for yield was the lowest (41.8%), indicating that the environment has a substantial effect on yield. In addition, there was a significant association between the presence/absence of certain bands and various phenotypic traits. CONCLUSION: ISSR markers are a powerful tool in distinguishing onion ecotypes. In addition, significant associations between marker scores and phenotypic traits could be detected, representing particular importance for future breeding programs.
ABSTRACT
Allium cepa L. remains the most cultivated Allium species in Morocco and around the world. With the purpose of making the first biochemical characterization of Moroccan onions, several biochemical components have been measured in eleven onion ecotypes. Onions were collected as seeds from different geographical origins and cultivated in the same environment, to eliminate the influence of the environment on biochemical expression. Moisture, total phenols, flavonoids, antioxidant activity, total and reducing sugars, and sulfur dioxide were the biochemical properties of interest. Except for moisture, the eleven onion ecotypes revealed a highly significant variation in terms of the studied biochemical characters. The total phenol and flavonoid content ranged from 5.94 to 11.22 mg equivalent gallic acid/g dry weight and 0.67 to 1.52 mg equivalent quercetin/g dry weight, respectively. The antioxidant activity of the studied onions showed a strong correlation with the polyphenols (R 2 = 0.7189), especially with the flavonoids (R 2 = 0.8063). The sulfur dioxide content parted from 85.60 to 30.43 ppm when measured using the Monier-Williams distillation method. The current results show that there is no correlation between total sugars and reducing sugars. In conclusion, these findings present a clear biochemical profile of Moroccan onion ecotypes, as well as confirm, for the first time, the presence of a clear variation between the biochemical profiles of Moroccan onion ecotypes, which could be useful for future valorization programs.
