EMS Induced Mutants In Dhurrin Production and Effects On Growth and Development Of Sorghum Bicolor (L.) Moench.

Sorghum is the fifth most important grain crop in the world. It is a staple food crop in many countries in the semi-arid tropics. Sorghum is also commercially important as a feed, forage, and silage crop in many different parts of the world. One factor that can affect sorghum forage quality is dhurrin production, a cyanogenic glucoside naturally produced in the plant. When tissues containing dhurrin are consumed, HCN is released during dhurrin decomposition. While there is natural genetic diversity for dhurrin production in sorghum lines, there have been no naturally-occurring, dhurrin-free genotypes identified to date. We screened a large population of EMS chemical mutants of sorghum and identified a series of genotypes that have disruptions in the biosynthetic and catabolic pathways in dhurrin metabolism. One of these lines, EMS 2447, has a C493Y mutation in CYP79A1, the first enzyme in the dhurrin biosynthetic pathway . Previous studies have shown that plants with a mutation in this gene had slower seedling growth compared to wild type plants. We conducted an experiment to test the effects of the C493Y mutation on growth and development of sorghum seedlings in segregating F2 families to reduce the impact of other EMS mutations in the background of our mutant line. Measurements of plant growth and leaf greenness showed few significant differences between mutant and wild type plants. These results suggest that this mutation may have value in developing new forage sorghum cultivars with reduced risk of dhurrin toxicity.