RESUMEN
In recent years the biosynthesis of auxin has been clarified with the aid of mutations in auxin biosynthesis genes. However, we know little about the effects of these mutations on the seed-filling stage of seed development. Here we investigate a key auxin biosynthesis mutation of the garden pea, which results in auxin deficiency in developing seeds. We exploit the large seed size of this model species, which facilitates the measurement of compounds in individual seeds. The mutation results in small seeds with reduced starch content and a wrinkled phenotype at the dry stage. The phenotypic effects of the mutation were fully reversed by introduction of the wild-type gene as a transgene, and partially reversed by auxin application. The results indicate that auxin is required for normal seed size and starch accumulation in pea, an important grain legume crop.
Asunto(s)
Ácidos Indolacéticos/farmacología , Pisum sativum/metabolismo , Semillas/anatomía & histología , Almidón/biosíntesis , Ácido 2,4-Diclorofenoxiacético/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Genes de Plantas , Germinación/efectos de los fármacos , Germinación/genética , Mutación/genética , Tamaño de los Órganos/efectos de los fármacos , Pisum sativum/efectos de los fármacos , Pisum sativum/embriología , Pisum sativum/ultraestructura , Fenotipo , Plantas Modificadas Genéticamente , Plantones/efectos de los fármacos , Plantones/genética , Plantones/crecimiento & desarrollo , Semillas/efectos de los fármacos , Semillas/ultraestructura , Sacarosa/metabolismo , Factores de Tiempo , Cigoto/efectos de los fármacos , Cigoto/metabolismoRESUMEN
Seeds of several agriculturally important legumes are rich sources of the only halogenated plant hormone, 4-chloroindole-3-acetic acid. However, the biosynthesis of this auxin is poorly understood. Here, we show that in pea (Pisum sativum) seeds, 4-chloroindole-3-acetic acid is synthesized via the novel intermediate 4-chloroindole-3-pyruvic acid, which is produced from 4-chlorotryptophan by two aminotransferases, TRYPTOPHAN AMINOTRANSFERASE RELATED1 and TRYPTOPHAN AMINOTRANSFERASE RELATED2. We characterize a tar2 mutant, obtained by Targeting Induced Local Lesions in Genomes, the seeds of which contain dramatically reduced 4-chloroindole-3-acetic acid levels as they mature. We also show that the widespread auxin, indole-3-acetic acid, is synthesized by a parallel pathway in pea.