Mutator transposon activity reprograms the transcriptomes and proteomes of developing maize anthers

Abstract

SUMMARYDespite the high conservation of anther gene expression patterns across maize lines, Mu transposition programmed by transcriptionally active MuDR results in a 25% change in the transcriptome, monitored over 90 h of immature anther development, without altering the morphology, anatomy or pace of development. Most transcriptome changes are stage specific: cases of suppression of normal transcripts and ectopic activation are equally represented. Protein abundance changes were validated for numerous metabolic enzymes, and highlight the increased carbon and reactive oxygen management in Mutator anthers. Active Mutator lines appear to experience chronic stress, on a par with abiotic treatments that stimulate early flowering. Despite the diversity of acclimation responses, anther development progresses normally, in contrast to male-sterile mutants that disrupt anther cell fate or function completely, and cause fewer transcriptome changes. The early flowering phenotype ultimately confers an advantage in Mu element transmission.

Transcriptomic, proteomic and metabolomic analysis of maize responses to UV-B

“…Hybridization signals were scored as present if the signal was three-fold above the standard deviation of the average hybridization to the negative control (non-hybridizing) probes. 12 Transcriptome differences were assessed from leaf or ear samples pooled from four individuals and four independent biological replicates were performed with symmetrical dye labeling to minimize systematic errors. 13 As shown in Table 1, maize leaves (L) and immature ears (IE) express a substantial number of genes.…”

“…Two-dimensional DIGE and mass spectrometry were used to identify differentially accumulated proteins. 11,12,16 Figure 3A shows that, of the 58 total protein spots that were changed by the 4 h UV-B treatment in 2L IR greenhouse leaves compared to the NI control plants, only 24% were changed in a similar way in 2L IR field leaves. Common proteome changes include the upregulation of some photosynthetic proteins (fructose-bisphosphate aldolase, pyruvate phosphate dikinase, chlorophyll a-b binding protein 1) and a cytosolic ascorbate peroxidase; as well as the downregulation of other photosynthetic proteins including both RUBISCO and an oxygenevolving enhancer protein 1 (Sup.…”

Production of Viable Gametes without Meiosis in Maize Deficient for an ARGONAUTE Protein

“…Because the ago104 mutants used in our experiments were derived from Mu-active stocks, we cannot discard the possibility that the differences observed in the transcriptomic data relate to Mu activity. Strong transcriptional effects of Mu activity, which can reprogram the transcriptome of developing maize anthers, have been well documented (Skibbe et al, 2009). Further experiments are thus required to define more precisely the contribution of an ago104-dependent pathway to transcriptional control in the ovule.…”

Mutator and MULE Transposons

“…The fact that lines that share few of the same insertions exhibit similar phenotypes suggests that Mutator syndrome represents a generic effect of activity rather than the effects of specific insertions. Further, a comparison of RNA and protein in plants with Mutator activity and related individuals that had lost activity revealed dramatic changes in gene expression in response to Mutator activity (45). Interestingly, many of the differentially expressed genes encode proteins involved in stress response, suggesting that Mutator activity represents a chronic stressor.…”