Mutations in the Phenylpropanoid and Starch Synthesis Pathways Are Important Determinants of Seed Longevity in Garden Pea (Pisum sativum L.) Stored at Cool Temperatures

Two well-known recessive mutations (a, conditioning white flowers and unpigmented testa; and r, conditioning wrinkled seeds) were found to be major contributors to the loss of germination percentage in garden pea (Pisum sativum L.) when seeds were maintained at cool temperatures (5 °C) for extended periods. After approximately 20 years in storage, seeds homozygous for the unpigmented mutation displayed an average germination rate about 20% lower than wildtype seeds, while wrinkled seeds displayed a rate about 25% less. Seeds homozygous for both the a and r mutations (a combination typical of many commercial cultivars) exhibited a reduction in germination percentage of about 50% over the storage period, indicating that the two mutations have an additive effect on the ageing process. Additional results involving a second mutation (a2) in the phenylpropanoid pathway, as well as information available from the literature that a second, independent mutation in starch synthesis (rb) also reduces seed longevity, suggest that an intact phenylpropanoid pathway and a normally functioning starch synthesis pathway are necessary for optimal storage life of pea seeds.