Production and evaluation of indehiscent mutant genotypes in Euphorbia lagascae

Abstract Euphorbia lagascae is an annual species endemic to southern Spain and Sardinia. It is characterized by its unique seed oil content (42%) consisting of about 60% vernolic acid (cis 12,13-epoxy oleic acid) with attractive applications in oleochemistry. However, severe seed shattering was universal in wild accessions collected all over its area of native distribution. For this reason, mutagenic EMS seed treatments were conducted and progenies grown in the field. Indehiscent phenotypes were found, one in the M 2 and two in the M 3 generation and their inheritance was confirmed in consecutive generations. However, the first mutant, which exhibited perfect penetrance of the mutated trait, i.e. all capsules being indehiscent, was associated with insufficient transmission evidently caused by partial sterility. The other two mutants, which were not affected by sterility constraints, exhibited lower degree of expression for seed retention. They had no more than 80% of their capsules closed with complete seed retention. Histological investigations revealed that a missing mesocarp layer in the capsule wall was causal for the indehiscence trait. With the basic material now available, breeding for further improvement and final establishment of varieties for agricultural production are promising. Corresponding strategies have been discussed and are being pursued.