This document provides oilseed plants (e.g., pennycress plants) having increased levels of one or more saturated fatty acids, increased levels of one or more polyunsaturated fatty acids (PUFAs), altered (e.g., increased or decreased) levels of oleic acid, and/or altered (e.g., increased or decreased) levels of erucic acid. For example, oilseed plants having reduced polypeptide levels and/or reduced polypeptide activity of one or more polypeptides involved in triglyceride synthesis (e.g., diacylglycerol O-acyltransferase 1 (TAG1) can have increased levels of stearic acid, increased levels of one or more PUFAs, altered levels of oleic acid, and/or altered levels of erucic acid. Also provided herein are methods and materials for making and using oilseed plants having increased levels of one or more saturated fatty acids, increased levels of one or more PUFAs, altered levels of oleic acid, and/or altered levels of erucic acid.
