Four New Soybean Sources Carrying Novel SACPD-C Alleles Containing High Level of Seed Stearic Acid and Conferring Resistance to Soybean Cyst Nematode

The alteration of fatty acid profiles to improve soybean oil quality has been a long time goal of many researches through the world. Biodiesel is an up and coming trend in energy production. Breeding effort can be undertaken in order to produce higher energy profile soybean oil. Using the ethyl-methanesulfonate (EMS) mutagenesis effects on DNA, significant changes to the genes and gene network underlying oil profile can be achieved, these changes are hard to accomplish under standard breeding techniques. High content Linolenic acid is very important for fuel and Biodiesel production, but disadvantageous for food production due to the fact that the oil is oxidized easily and the foods go rancid quickly. However, Soybean oil with elevated Stearic and Oleic acids is desirable for food. Oleic acid is a monounsaturated fatty acid that improves the nutrition and oxidative stability of soybean oil compared to other oils. Stearic acid is also a desirable constituent of oils for food use because it is less likely to be incorporated into cholesterol esters and has a neutral effect on the concentration of the blood serum LDL cholesterol. Stearic acid may be useful to eliminate the need for chemical hydrogenation of soybean oil in the production of trans-free margarines and shortenings. In order to improve the quality of soybean oil and processed foods, chemically mutagenized soybean using EMS has been developed in this work. Seeds harvested from individual M3 and M4 plants (from 2 successive years 2012 and 2013) were analyzed for Protein content, oil composition and levels. The main purposes of this work were to mutation breed new soybean [Glycine max (L.) Merr.] sources containing high level of seed stearic acid, Oleic and Linolenic good for the soy industrial and food production, on the background conferring the resistance to soybean cyst nematode (SCN), the most devastating pest in soybean production, and to analyze the mutations of the SACPD and FAD2 genes encoding the delta-9-steoryl-acyl-carrier protein desaturase and Fatty acid desaturase respectively. Four soybean mutants were forward genetically identified with high level of seed stearic acid, presenting between 2.1 to 3.3 times the levels contained in the wild-type seed of the Forrest soybean, from this M3/M4 population of 1058 families. Second, all these 4 mutants were further identified to carry one mutation each in one SACPD isoform (SACPD-C), but no mutations in the other two SACPD isoforms (SACPD-A and SACPD-B). SACPD catalyzes the conversion of stearic acid to oleic acid. In the same way, 2 mutants with high levels of Oleic acid were identified presenting 2.5 times more content than the Forrest WT. The two mutants were further identified to carry one mutation each in both FAD2-1A and FAD2-1B isoforms, which converts Oleic acid to Linoleic acid. All these 6 mutants are still highly resistant to SCN like the wild type Forrest. The screened six SACPD-C, FAD2-1A and FAD2-1B mutants may be used as a new soybean sources (germplasm) not only containing high seed stearic and Oleic acids but also conferring SCN resistance.