Development of pre-breeding diploid potato germplasm displaying wide phenotypic variations as induced by ethyl methane sulfonate mutagenesis

Abstract

Mutations are the key drivers for evolution and diversification in plants. In varietal selection, sources for variation are always sought as starting breeding materials. Thus, in the absence of desired natural variations in breeding populations, targeted or random mutagenesis is applied to induce variations. Cultivated potato (Solanum tuberosum L.) is autotetraploid crop species with a narrow and highly heterozygous genetic base, and the complexity of its genome makes its genetic studies more difficult. In the current study, induced mutagenesis was performed in diploid potato using ethyl methane sulfonate (EMS) to enlarge the genetic variability for its use as pre-breeding materials in both polyploid and diploid potato breeding. As starting materials, true potato seeds were treated with 1.2% EMS for 4-6 h along with untreated seeds as controls. A large variation in terms of germination rate, plant, flower, and tuber phenotype was observed in EMS-treated plants compared with their untreated counterparts. In particular, abnormal phenotypes including twisted stem, partial and (or) completely chlorotic leaves and stems, variations in stem colour and weak-stemmed plants with lateral growth habit as well as plants with determinate growth habit were observed along with normal plant characteristics. Moreover, variations in flower colour and tuber colour, shape, and size, as well as yield potential, were observed in EMS-treated lines. The reported phenotypic characterization of EMS mutagenized diploid potato collection is to our knowledge the first in its kind and represents a premium genetic resource for potato breeding programs and plant biologists for genes functional characterization in potato.

Diversity in genetic and downy mildew resistance among wild and mutagenized hops as revealed by single nucleotide polymorphisms and disease rating

“…Using SNP polymorphism data derived from seven genes involved in bittering acid production (Paniego et al 1999;Clark et al 2013;Li et al 2015), the current study revealed a large variation (natural and EMS-induced) in hop seedlings, true hop seeds, and mutagenized explant clones derived from Alpharoma. Similar EMS-induced SNP variations have been reported in flax, potato, tomato, and eggplants (Muth et al 2008 Chantreau et al 2013;Shikata et al 2015;Fofana et al 2017;Xiou et al 2017;Somalraju et al 2018). By challenging wild and EMS-treated clones with DM, a diversity in disease response was observed in both types, suggesting that wild feral types had persisted and co-evolved in the environment with epiphytotic DM epidemics and might have developed adaptation mechanisms through natural mutations during the nearly 200 years of co-evolution with different local DM strains.…”

“…Using Alpharoma as starting material, internodes were collected from in vitro plants and treated with different concentrations (0.25%, 0.5%, or 1% (v/v)) of EMS diluted in sterile water for 1 or 3 h. The treated internodes were rinsed five times with water as described by Somalraju et al (2018). The explants were incubated in callus induction media (Batista et al 2000) and plants were regenerated (Roy et al 2001).…”

“…The plated seeds were incubated at room temperature, and seed germination was recorded for two months. After the pre-germination test, 1052 and 1500 seeds from P-RL-6 were treated with 0.5% and 1% EMS for 6 h, respectively, whereas 841 and 1500 seeds from P-RL-7 were treated with the same respective EMS concentrations for 5 h, following the procedures described for true potato seed by Somalraju et al (2018). A total of 555 seeds from P-RL-4 were treated with water and used as the non-treated control.…”

“…According to available literature, most of the current commercial hop cultivars in North America can be traced back to common ancestries involving Brewers Gold and Northern Brewers (Hampton et al 2001;Driskill et al 2022) and are mostly susceptible to common diseases of hops (Salmon and Ware 1931), highlighting their narrow genetic diversity (Patzak et al 2010). In the past decades, the genetic diversity of many crops have been broadened through artificially-induced mutagenesis, as performed in flax (Chantreau et al 2013;Fofana et al 2017), potato (Muth et al 2008;Somalraju et al 2018), tomato (Shikata et al 2015), and eggplant (Xi-ou et al 2017).…”

Foliar selenium application reduces late blight severity and incidence in potato and acts as a pathogen growth inhibitor and elicitor of induced plant defence

“…The plant materials used in this study consisted of four potato genotypes including two registered varieties ('Superior' and 'Russian Blue') and two EMSmutagenized diploid potato lines ('EMS5-512ʹ and 'EMS4-901ʹ) derived from a diploid EMS-mutagenized potato genetic resource (Somalraju et al 2018). 'Superior' and 'Russian Blue' cultivars have contrasting tuber skin and flesh colours.…”