Water-deficit stress during meiosis is one of the most serious threats to crop production. To elucidate the mechanisms of the response to water-deficit stress in the reproductive organs of maize, we have characterized the changes in transcription that occur during meiosis in the tassels and floret formation in the ears following water deficit stress. We used oligo microarray analysis, which included 57,452 transcripts representing more than 30,000 identifiable unique maize genes, and combined this with reverse Northern blot analysis. After 7 days of stress, immature tassels and ears differed considerably in their transcriptional responses, and the majority of changes were organ specific. In the tassels, 1,513 transcripts were differentially expressed (by threefold or greater) with 62% of these being upregulated by water stress. In the ears, 202 transcripts were differentially expressed with 95% being upregulated by water stress. Most of these transcripts have not been previously reported to be associated with water stress. Only 74 of these transcripts were co-regulated in the two organs. The stress-regulated transcripts are involved in a broad range of cellular and biochemical activities. The most notable may function in carbohydrate metabolism, particular in sucrose, trehalose and raffinose metabolism, and in cell wall metabolism in the tassels. Collectively, these data suggest that the transcripts differentially expressed during reproductive organic development may represent candidate genes for dissecting molecular mechanism of this important biological process in response to water-deficit stress.

No abstract

No abstract

A putative glutamate decarboxylase (GAD) gene, designated ZmGAD1, was cloned from Zea mays with a combination of reverse-transcriptase polymerase chain reaction (RT-PCR) and bioinformatic approaches. The ZmGAD1 cDNA sequence contained a complete open reading frame encoding a putative protein of 496 amino acids, which contained a pyridoxal-5′-phosphate binding domain and a calmodulin (CaM)-binding domain found in nearly all GADs from plants. Sequence analysis showed that it had highest similarity with rice GAD1. Recombinant ZmGAD1 protein was expressed in Escherichia coli, purified and used to measure enzyme activity, which confirmed ZmGAD1 was really a glutamate decarboxylase gene. Southern blotting analysis suggested that ZmGAD1 was present as a single copy gene in the maize genome. RT-PCR analysis revealed that ZmGAD1 was expressed in all examined tissues including the roots, stems, leaves, ears, and tassels. The expression of the ZmGAD1 gene was upregulated and GAD activity was increased in the leaves and roots after treatment with ABA, MeJA, NaCl, PEG, or cold stress. Several stress-related ciselements were present in the ZmGAD1 promoter cloned from maize genomic DNA. These results suggested that ZmGAD1 might play an important role in responses to abiotic factors and hormone treatments.

Articles you may be interested inDirect measurement of the linewidth enhancement factor by optical heterodyning of an amplitudemodulated quantum cascade laser