Mutagenic influences of colchicine on phenological and molecular diversity of Calendula officinalis L.

Six different colchicine concentrations: 0, 400, 800, 1200, 1600, and 2000 ppm, in combination with four soaking time treatments (1, 2, 3, and 4 h), were selected to assess the effects on germination, vegetative growth, and flower yield components in calendula plants. The molecular diversity among the treatments was assessed using ten SRAP marker combinations. Seed soaking in colchicine significantly enhanced both the fresh and the dry shoot and root masses, flowering date, number of flowers per plant, and flower diameter. At 1200-ppm colchicine combined with a 4-h soaking time, a superior effect on seed germination was observed, whereas 800 ppm for 4 h produced the highest number of flowers and the largest flower diameter. The earliest flowering time was found at 800 ppm combined with a short soaking time (1 h), while the 4-h soaking time with 800 ppm, is recommended for growing calendula outdoors, since it enhances flower development. At the molecular level, 752 fragments were successfully amplified using the SRAP primers, with 280 genetic loci found throughout the calendula genome. The polymorphism percentage ranged from 79 to 100% and the polymorphic information content (PIC) values ranged between 0.85 and 0.97. The high number of detected loci and PIC values suggests a great power of SRAP markers in detecting mutant molecular diversity. Our results clearly show the existence of genetic variation among colchicine treated calendula plants and the clustering of the studied mutants was concordant with the colchicine concentration used.

Phenotypic and biochemical profile changes in calendula (Calendula officinalis L.) plants treated with two chemical mutagenesis.

Chemical mutagenesis is an efficient tool used in mutation-breeding programs to improve the vital characters of the floricultural crops. This study aimed to estimate the effects of different concentrations of two chemical mutagens; sodium azide (SA) and diethyl sulfate (DES). The vegetative growth and flowering characteristics in two generations (M1 and M2) of calendula plants were investigated. Seeds were treated with five different concentrations of SA and DES (at the same rates) of 1000, 2000, 3000, 4000, and 5000 ppm, in addition to a control treatment of 0 ppm. Results showed that lower concentrations of SA mutagen had significant effects on seed germination percentage, plant height, leaf area, plant fresh weight, flowering date, inflorescence diameter, and gas-exchange measurements in plants of both generations. Calendula plants tended to flower earlier under low mutagen concentrations (1000 ppm), whereas higher concentrations delayed flowering significantly. Positive results on seed germination, plant height, number of branches, plant fresh weight, and leaf area were observed in the M2-generation at lower concentrations of SA (1000 ppm), as well as at 4000 ppm DES on number of leaves and inflorescences. The highest total soluble protein was detected at the concentrations of 1000 ppm SA and 2000 ppm DES. DES showed higher average of acid phosphatase activity than SA. Results indicated that lower concentrations of SA and DES mutagens had positive effects on seed germination percentage, plant height, leaf area, plant fresh weight, flowering date, inflorescence diameter, and gas-exchange measurements. Thus, lower mutagen concentrations could be recommended for better floral and physio-chemical performance.