Project description:Pollen tubes extend through pistil tissues and are guided to ovules where they release sperm for fertilization. Although pollen tubes can germinate and elongate in a synthetic medium, their trajectory is random and their growth rates are slower compared to growth in pistil tissues. Furthermore, interaction with the pistil renders pollen tubes competent to respond to guidance cues secreted by specialized cells within the ovule. The molecular basis for this potentiation of the pollen tube by the pistil remains uncharacterized. We used a surgical procedure to obtain large quantities of uncontaminated pollen tubes that grew through the pistil and defined their transcriptome by microarray analysis. We also characterized the transcriptome of in vitro-grown pollen tubes (for 0.5hours or 4hours) and dessicated mature pollen in Arabidopsis. Experiment Overall Design: Pollen and pollen tubes were collected as described in the protocols section for RNA extraction and hybridization on Affymetrix ATH1 Genechip microarrays.
Project description:In this study, we sequenced four small RNA libraries derived from mature pollens, in vitro germinated pollens, mature silks and pollinated silks of maize, respectively. In total, 161 known miRNAs belonging to 27 families and 82 novel miRNAs were identified. Of them, miRNAs involved in pollen-silk (pistil) interactions were analyzed. On the male side, miRNA differentially expressed between mature and germinated pollen were identified, some of them participate in pollen germination and tube growth. On the female side, silk-expressed miRNAs respond to pollination were also responsive to stresses, especially drought and fungal invasion. Furthermore, GO analysis of target genes revealed that members related to anxin signal transduction and gene expressional regulation were overrepresented.The results indicated that during pollen-silk interactions, miRNAs-mediated auxin signal transduction plays important roles, and miRNAs took part in complex transcriptional regulating network. Examination of 4 different tissues of maize to provide novel information for understanding the post-transcriptional regulations of pollen-pistil interactions
Project description:Heat stress is a major cause for yield loss in many crops, including vegetable crops. Even short waves of high temperature, becoming more frequent during recent years, can be detrimental. Pollen development is most heat-sensitive, being the main cause for reduced productivity under heat-stress across a wide range of crops. The molecular mechanisms involved in pollen heat-stress response and thermotolerance are however not fully understood. Recently, we have demonstrated that ethylene, a gaseous plant hormone, plays a role in tomato (Solanum lycopersicum) pollen thermotolerance. These results were substantiated in the current work showing that increasing ethylene levels by using an ethylene-releasing substance, ethephon, prior to heat-stress exposure, increased pollen quality. A proteomic approach was undertaken, to unravel the mechanisms underlying pollen heat-stress response and ethylene-mediated pollen thermotolerance in developing pollen grains. Proteins were extracted and analyzed by means of a gel LC-MS fractionation protocol, and a total of 1355 proteins were identified. A dataset of 721 proteins, detected in three biological replicates of at least one of the applied treatments, was used for all analyses. Quantitative analysis was performed based on peptide count. The analysis revealed that heat-stress affected the developmental program of pollen, including protein homeostasis (components of the translational and degradation machinery), carbohydrate and energy metabolism. Ethephon-pretreatment shifted the heat-stressed pollen proteome closer to the proteome under non-stressful conditions, namely, by showing higher abundance of proteins involved in protein synthesis, degradation, tricarboxylic acid cycle and RNA regulation. Furthermore, up-regulation of protective mechanisms against oxidative stress was observed following ethephon-treatment (including higher abundance of glutathione-disulfide reductase, glutaredoxin and protein disulfide isomerase). Taken together, the findings identified systemic and fundamental components of pollen thermotolerance, and serve as a valuable quantitative protein database for further research.
Project description:We used tomato pollen in order to identify pollen stage-specific small non-coding RNAs (sncRNAs) and their target mRNAs. We further deployed elevated temperatures to discern stress responsive sncRNAs. For this purpose high throughput sncRNA-sequencing was performed for three-replicated sncRNAs libraries derived from tomato tetrad, post-meiotic, and mature pollen under control and heat stress conditions.