RESUMO
Maintenance and release of seed dormancy is regulated by plant hormones; their levels and seed sensitivity being the critical factors. This study reports transcriptional regulation of brassinosteroids (BR), ethylene (ET), cytokinin (CK) and salicylic acid (SA) related wheat genes by after-ripening, a period of dry storage that decays dormancy. Changes in the expression of hormonal genes due to seed after-ripening did not occur in the anhydrobiotic state but rather in the hydrated state. After-ripening induced dormancy decay appears to be associated with imbibition mediated increase in the synthesis and signalling of BR, via transcriptional activation of de-etiolated2, dwarf4 and brassinosteroid signaling kinase, and repression of brassinosteroid insensitive 2. Our analysis is also suggestive of the significance of increased ET production, as reflected by enhanced transcription of 1-aminocyclopropane-1-carboxylic acid oxidase in after-ripened seeds, and tight regulation of seed response to ET in regulating dormancy decay. Differential transcriptions of lonely guy, zeatin O-glucosyltransferases and cytokinin oxidases, and pseudo-response regulator between dormant and after-ripened seeds implicate CK in the regulation of seed dormancy in wheat. Our analysis also reflects the association of dormancy decay in wheat with seed SA level and NPR independent SA signaling that appear to be regulated transcriptionally by phenylalanine ammonia lyase, and whirly and suppressor of npr1 inducible1 genes, respectively. Co-expression clustering of the hormonal genes implies the significance of synergistic and antagonistic interaction between the different plant hormones in regulating wheat seed dormancy. These results contribute to further our understanding of the molecular features controlling seed dormancy in wheat.
Assuntos
Citocininas/farmacologia , Reguladores de Crescimento de Plantas/genética , Sementes/efeitos dos fármacos , Sementes/genética , Transcrição Gênica/genética , Triticum/efeitos dos fármacos , Triticum/genética , Aminoácido Oxirredutases/genética , Brassinosteroides/farmacologia , Etilenos/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Germinação/efeitos dos fármacos , Germinação/genética , Fenilalanina Amônia-Liase/genética , Dormência de Plantas/efeitos dos fármacos , Dormência de Plantas/genética , Ácido Salicílico/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genéticaRESUMO
Seed dormancy is an important trait in wheat (Trticum aestivum L.) and it can be released by germination-stimulating treatments such as after-ripening. Previously, we identified proteins specifically associated with after-ripening mediated developmental switches of wheat seeds from the state of dormancy to germination. Here, we report seed proteins that exhibited imbibition induced co-regulation in both dormant and after-ripened seeds of wheat, suggesting that the expression of these specific proteins/protein isoforms is not associated with the maintenance or release of seed dormancy in wheat.
