Effects of water-deficit stress on the transcriptomes of developing immature ear and tassel in maize

Abstract

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.

Effects of Drought on Gene Expression in Maize Reproductive and Leaf Meristem Tissue Revealed by RNA-Seq

“…The pattern observed for starch and Suc metabolism-associated genes in drought-stressed ovaries suggests such an influence of the SnRK1 complex. The responses reported here that are related to raffinose and trehalose metabolism-associated genes were also reported by Zhuang et al (2007) for drought-stressed ear and tassels that were undergoing meiosis. This suggests that these stress responses, at least, are not specific to fertilized ovaries but also occur at earlier stages.…”

“…A small complementary DNA (cDNA) microarray containing about 2,500 cDNAs from maize was used to monitor gene expression specifically in developing maize endosperm and placenta/pedicel tissues during water deficit and rewatering at 9 DAP (Yu and Setter, 2003), a time when endosperm and placental tissues could be clearly distinguished. A transcriptomic study of the effect of drought on maize ears and tassels undergoing meiosis revealed raffinose and trehalose-associated genes as well as other carbohydrate-related processes (Zhuang et al, 2007). Beyond these observations, little is understood about the chain of molecular events leading to early embryo abortion in drought-stressed maize, and virtually nothing is understood about crucial events occurring upon fertilization.…”

“…Gene expression studies in maize in response to water stress have been conducted in roots (Poroyko et al, 2007), seedlings (Zheng et al, 2004), and developing ear and tassel (Zhuang et al, 2007). Genome-wide comparisons between the drought stress responses across different developmental stages in maize have not yet been made.…”

Sugarcane Responses at Water Deficit Conditions

“…The regulatory genes involve proteins whose roles are related to signaling and transcription factors (Shinozaki & Yamaguchi-Shinozaki, 2007). In general, all biological processes are affected by water deprivation; however plants under water stress are more susceptible to other stresses (Zhuang et al, 2007). Temperature is one of the factors that can enhance the effect of water stress on plants.…”

“…The identification and characterization of genes involved in drought tolerance brings knowledge about the perception of the stress and how plants respond to this adverse condition. Concerning this, studies have been performed aiming to identify new sources of variability in different crops (Cramer et al, 2007;Micheletto et al, 2007;Poroyko et al, 2007;Zhuang et al, 2007). Drought is firstly detected by root tissues.…”