In vitro mutagenesis in anthurium induced by colchicine

Developing new varieties of anthurium by hybridization can take 8-10 years; therefore, induced mutagenesis can be an alternative strategy to hybridization. The objective of this work was to induce mutations in A. andreanum by exposing explants obtained from vitroplants to colchicine. Explants of leaves, nodes and roots obtained from vitroplants were exposed to 0.1 % colchicine for 0, 2, 3 and 4 h. The mean lethal dose (LD50), survival, number of explants that generated callus, number of explants that formed shoots and the number of shoots per explant were evaluated. The karyotype of the presumed mutated regenerated plants was determined by the root apex squash technique. The leaves showed the highest sensitivity to cochicine. The survival of the root explants treated with colchicine was 100 %; 4 % of roots exposed for 2 and 3 h formed adventitious shoots (120 shoots). For nodes, the LD50 was found at 3.98 h; 76 and 56 % of the nodes cultivated for 2 and 3 h with colchicine formed adventitious shoots (4.4 and 3.6 shoots). The plants regenerated from the explants exposed to colchicine showed morphological changes. The chromosomal number of the regenerated vitroplants from the explants exposed for 2 and 3 h to colchicine was 2n = 29, while that of those obtained from the explants that remained on the colchicine for 4 h was 2n = 31. The sensitivity to colchicine was a function of the type of explant and the dose used. Colchicine caused the loss (monosomy) or gain of chromosomes (trisomy).

Comparative Analysis Reveals Changes in Some Seed Properties in Amaranth Mutant Variety ‘Zobor’ (A. hypochondriacus × A. hybridus)

The aim of our long-term research program is to improve the quality and quantity of amaranth production through mutation breeding using γ-radiation. In this paper, we present the characterization of the new variety ‘Zobor’ of A. hypochondriacus × A. hybridus developed by radiation-induced mutagenesis of hybrid K-433. Multiyear phenotypic characterization of an important yield parameter (1000-seed weight) showed that the studied mutant variety ‘Zobor’ has an advantage in seed weight over the nonirradiated control seeds of K-433 with predictable performance of this yield trait. ‘Zobor’ exhibited changes in seed morphometric parameters, starch particle size, and pasting properties with no change in amylose content and swelling power. Moreover, the seeds of ‘Zobor’ showed the significantly highest folate content among selected amaranth varieties. The mutant variety could, therefore, be interesting for the development of functional foods and as a low-management crop, attractive for cultivation in Europe.

iMUT-seq: high-resolution mapping of DSB mutational landscapes reveals new insights into the mutagenic mechanisms of DSB repair

DNA double-strand breaks (DSBs) are the most mutagenic form of DNA damage, and play a significant role in cancer biology, neurodegeneration and aging. However, studying DSB-induced mutagenesis is currently limited by the tools available for mapping these mutations. Here, we describe iMUT-seq, a technique that profiles DSB-induced mutations at high-sensitivity and single-nucleotide resolution around endogenous DSBs spread across the genome. By depleting 20 different DSB-repair factors we defined their mutational signatures in detail, revealing remarkable insights into the mechanisms of DSB-induced mutagenesis. We find that homologous-recombination (HR) is mutagenic in nature, displaying high levels of base substitutions and mononucleotide deletions due to DNA-polymerase errors, but simultaneously reduced translocation events, suggesting the primary role of HR is the specific suppression of genomic rearrangements. The results presented here offer new fundamental insights into DSB-induced mutagenesis and have significant implications for our understanding of cancer biology and the development of DDR-targeting chemotherapeutics.

Physio-biochemical Parameters of Ajwain (Trachyspermum ammi L.) Induced by Gamma Rays and EMS

Background: Induced mutagenesis has proved as a crucial implement to create genetic variability for various essential traits. Trachyspermum ammi is one of the most important medicinal seed spices and its oil exhibits various pharmacological properties. Ajwain has been overlooked owing its narrow genetic base and little study has been performed to create genetic variations. Methods: Dry and healthy seeds of ajwain were treated with the different concentration of gamma rays (25,50,75 and 100Gy), EMS (0.1%, 0.2%, 0.3% and 0.4%EMS) and different doses of combination treatments (25+0.1%, 50+0.2%, 75+0.3% and 100Gy+0.4%EMS). Among both the mutagens, gamma rays were found to be more effectual mutagens as compared to EMS. Result: The aim of the present study was to find out the mutagenic consequences of gamma rays, EMS and combination treatments on growth and physio-biochemical parameters of ajwain. Studies show that higher doses of both the mutagens caused significantly negative effect on the growth parameters whereas lower doses have positively influenced the parameters. Result shows lower doses of mutagens (25, 50Gy, 0.1%, 0.2%EMS and 25+0.1%, 50Gy+0.2%EMS) proved to be more effective as it caused less biological damage and therefore would be suitable for inducing the desirable mutations and improving the agronomic traits in ajwain.

Mechanisms generating the numerous hues of chrysanthemum petals can be traced to in vitro γ-ray-induced mutagenesis.

In terms of global cut flower production, chrysanthemum (Dendranthemum grandiflorum kitam.) ranks among the top ten. When a plant species possesses colour characteristics associated with those of ancestral species, that colour is described as being white, yellow, or pink, with white coloration representing an absence of pigments, and yellow and pink coloration each represents the presence of carotenoids and anthocyanins, respectively. Pigments, or a combination of pigments, have been improved upon to provide an expansive rainbow of floral colours like orange, dark red, purplish-red, and red. Recent green-flowered varieties have developed a reputation for containing chlorophylls in their ray petals. Additionally, transgenic interventions have been used to breed violet/blue flowers. Flower colour is a highly regarded characteristic of any flower cultivar, particularly chrysanthemum. Breeders' ultimate goal is to create newer chrysanthemum cultivars with innovative characteristics, such as new flower colours, using a time and input-efficient approach. Investigating the molecular mechanisms that regulate flower pigmentation may yield critical insights into the rational manipulation of floral colour. To generate a diverse array of flower colour mutants in chrysanthemum cv. “Candid” through mutagenesis, in vitro grown micro shoots were exposed to 10, 20, 30, and 40 Gy gamma irradiation at 100 Gy per minute and were evaluated for different parameters. The rhizogenesis parameters declined with the increase in irradiation dose from 0 Gy to 40 Gy, while as, 10 Gy dose proved to record minimum decline in contrast to the control. Survival, leaf size, and the number of leaves plant-1 after the 8th-week interval exhibited a downward trend with the increasing trend of gamma irradiation dose but recorded a least drop in plants raised from shoots irradiated with 10 Gy gamma irradiation dose with respect to the control. Apparently, the minimum delay in the number of days to floral bud appearance took under 10 Gy compared to control. The highest number of flower colour mutants was recorded under 10 Gy (light pink, orange-pink, white and yellow). Demountable mutation frequency based on flower colour was desirable in plants irradiated with the slightest dose of 10 Gy.

Precancerous liver diseases do not cause increased mutagenesis in liver stem cells

Inflammatory liver disease increases the risk of developing primary liver cancer. The mechanism through which liver disease induces tumorigenesis remains unclear, but is thought to occur via increased mutagenesis. Here, we performed whole-genome sequencing on clonally expanded single liver stem cells cultured as intrahepatic cholangiocyte organoids (ICOs) from patients with alcoholic cirrhosis, non-alcoholic steatohepatitis (NASH), and primary sclerosing cholangitis (PSC). Surprisingly, we find that these precancerous liver disease conditions do not result in a detectable increased accumulation of mutations, nor altered mutation types in individual liver stem cells. This finding contrasts with the mutational load and typical mutational signatures reported for liver tumors, and argues against the hypothesis that liver disease drives tumorigenesis via a direct mechanism of induced mutagenesis. Disease conditions in the liver may thus act through indirect mechanisms to drive the transition from healthy to cancerous cells, such as changes to the microenvironment that favor the outgrowth of precancerous cells.