Development of pre-breeding diploid potato germplasm displaying wide phenotypic variations as induced by ethyl methane sulfonate mutagenesis
Somalraju, A., Ghose, K., Main, D., Bizimungu, B., Fofana, B. (2019). Development of pre-breeding diploid potato germplasm displaying wide phenotypic variations as induced by ethyl methane sulfonate mutagenesis. Canadian Journal of Plant Science, [online] 99(2), 138-151. http://dx.doi.org/10.1139/cjps-2018-0189
Plain language summary
Genetic changes known as mutations lead to plant evolution and diversification, and are the key sources for variation in plant variety selection. When natural variations are limited in breeding materials, plant geneticists mimic natural evolution by inducing changes using physical or chemical agents. The cultivated potato has a narrow genetic diversity and a complex genetic make-up which makes its genetic studies difficult. Some wild relatives of cultivated potato have a smaller genetic make-up as they carry only half of the cultivated potato’s genetic make-up. Genetically, these wild types are easy to work with and can be used in cultivated potato breeding or can be grown on their own as varieties. In this study, the ultimate goal was to enlarge the genetic variability of wild potatoes and develop a pre-breeding plant collection for use in potato breeding. Researchers treated true potato seeds of wild potato species with a chemical agent capable of inducing genetic changes in the potato seed’s genetic make-up. After planting the seeds, the data showed a large difference in the plant, flower and tuber characteristics of treated plants compared with their non-treated counterparts. Along with normal plant characteristics, abnormal plant characteristics including twisted stems, partial and/or complete yellow of leaves and stems, as well as weak-stemmed plants with vine-like growth habit were also observed. Changes in the flower color, tuber color, shape, size and yield were also found in the treated potatoes as compared to the untreated potatoes. Overall, this new diverse potato plant collection represents a premium genetic resource for potato breeding programs and plant biologists for use in gene function studies.
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.