Abstract:

The embryos of dormant and non-dormant cultivars of wheat (Triticum aestivum L.) were treated with ABA and protein expression was compared on two-dimensional electrophoresis gels. The results showed that 18 ABA-responsive proteins were expressed differentially. Among them, 16 protein spots were identified using MALDI-TOF-MS analysis and database searching. According to their characters, they may participate in different reactions, such as cold regulated protein, heat shock protein HSP26, aldehyde dehydrogenase are involved in stress reaction; auxin-responsive-like protein, ethylene receptor, calcium dependent protein kinase CP4, putative ethylene-responsive protein refer to signal cross pathway; and LEA B19.1, LEA 1, Em protein, bZIP transcription factor, zinc finger protein, myb family transcription factor, starch synthase, putative cellulase play certain roles in the seed development. One of two unknown protein was a gene product without significant homology to any protein but with full-length cDNA or EST homology, which covers almost the entire length of partial sequence of rice. Another was not identified using MALDI-TOF-MS or ESI-MS/MS analysis and suggested to be a new ABA-responsive protein in ABA signal transduction system. The protein patterns were studied in different development stages, ABA concentrations and imbibed courses in dormant and non-dormant states, so as to analyze the relationship between this protein level and dormancy trait. The results indicated that the two proteins were synthesized in middle or late-stage of seed development, which is consistent with the behavior of dormancy. The expression of the two proteins was easier in dormant embryos than in non-dormant embryos. At least 5-fold ABA concentration was required to produce similar results in non-dormant embryos. During imbibition, the expression of the two proteins in dormant embryos was prolonged and disappeared with breaking of dormancy. It is suggested that the expression level of the two proteins has relation to the maintenance of seed dormancy states. It is possible to clone the encoding gene and identify its function to provide candidate loci for sprouting resistance breeding in wheat.

Key words: Wheat, Embryo, Seed dormancy, ABA signal transduction, Proteome