Biology subjects

Atwell, B. J.

Publications and source records attributed to Atwell, B. J..

3 recordsLinked to original sources

bioRxiv2021

Genome survey sequencing of wild cotton (Gossypium robinsonii) reveals insights into proteomic responses of pollen to extreme heat

Heat stress specifically affects fertility by impairing pollen viability but cotton wild relatives successfully reproduce in hot savannas where they evolved. An Australian heat-tolerant cotton (Gossypium robinsonii) was exposed to heat events during pollen development, then mature pollen was subjected to deep proteomic analysis using 57,023 predicted genes from a genomic database we assembled for the same species. Three stages of pollen development, including tetrads, uninucleate and binucleate microspores were exposed to 36{degrees}C or 40{degrees}C for 5 d and the resulting mature pollen was collected at anthesis (p-TE, p-UN and p-BN, respectively). Using SWATH-MS proteomic analysis, 2,704 proteins were identified and quantified across all pollen samples analyzed. Proteins predominantly decreased in abundance at all stages in response to heat, particularly after exposure of tetrads to 40{degrees}C. Functional enrichment analyses demonstrated that extreme heat increased the abundance of proteins that contributed to increased mRNA splicing via spliceosome, initiation of cytoplasmic translation and protein refolding in p-TE40. However, other functional categories that contributed to intercellular transport were inhibited in p-TE40, linked potentially to Rab proteins. We ascribe the resilience of reproductive processes in G. robinsonii at temperatures up to 40{degrees}C, relative to commercial cotton, to a targeted reduction in protein transport.

plant biology↗

bioRxiv2021

Patterns of gene expression in pollen of cotton (Gossypium hirsutum) indicate down-regulation as a feature of thermotolerance

Reproductive performance in plants is impaired as maximum temperatures consistently approach 40{degrees}C. However, the timing of heatwaves critically affects their impact. We studied the molecular responses of cotton male reproductive stages, to investigate the vulnerability of maturing pollen to high temperature. Tetrads, uninucleate and binucleate microspores, and mature pollen were subjected to SWATH-MS and RNA-seq analyses after exposure to 38/28{degrees}C (day/night) for 5 days. The results indicated that molecular signatures were down-regulated over developmental stages in response to heat. This was more evident in leaves where three-quarters of differentially changed proteins were decreased in abundance. Functional analysis showed that translation of genes increased in tetrads after exposure to heat; however, the reverse pattern was observed in mature pollen and leaves. Proteins involved in transport were highly abundant in tetrads, whereas in later stages of development and leaves, heat suppressed cell-to-cell communication. Moreover, a large number of heat shock proteins (HSPs) were identified in heat-affected tetrads, but these proteins were less abundant in mature pollen and leaves. We speculate that the sensitivity of tetrad cells to heat is related to increased activity of translation involved in non-essential pathways. Molecular signatures during pollen development after heatwaves provide markers for future genetic improvement.

plant biology↗

bioRxiv2021

The phosphoproteome of rice leaves responds to water and nitrogen supply

The scarcity of freshwater is an increasing concern in flood-irrigated rice, whilst excessive use of nitrogen fertilizers is both costly and contributes to environmental pollution. To co-ordinate growth adaptation under prolonged exposure to limited water or excess nitrogen supply, plants have processes for signalling and regulation of metabolic processes. There is limited information on the involvement of one of the most important post-translational modifications (PTMs), protein phosphorylation, on plant adaptation to long-term changes in resource supply. Oryza sativa cv. Nipponbare was grown under two regimes of nitrogen from the time of germination to final harvest. Twenty-five days after germination, water was withheld from half the pots in each nitrogen treatment and low water supply continued for an additional 26 days, while the remaining pots were well watered. Leaves from all four groups of plants were harvested after 51 days in order to test whether phosphorylation of leaf proteins responded to prior abiotic events. The dominant impact of these resources is exerted in leaves, where PTMs have been predicted to occur. Proteins were extracted and phosphopeptides were analysed by nanoLC-MS/MS analysis, coupled with label-free quantitation. Water and nitrogen regimes triggered extensive changes in phosphorylation of proteins involved in membrane transport, such as the aquaporin OsPIP2-6, a water channel protein. Our study reveals phosphorylation of several peptides belonging to proteins involved in RNA-processing and carbohydrate metabolism, suggesting that phosphorylation events regulate the signalling cascades that are required to optimize plant response to resource supply.

plant biology↗