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The Heat Shock Factor (HSF) transcription factor family is a central and required component of plant heat stress responses and acquired thermotolerance. The HSF family has dramatically expanded in plant lineages, often including a repertoire of 20 or more genes. Here we assess and compare the composition, heat responsiveness, and chromatin profiles of the HSF families in maize andSetaria viridis(Setaria), two model C4 panicoid grasses. Both species encode a similar number of HSFs, and examples of both conserved and variable expression responses to a heat stress event were observed between the two species. Chromatin accessibility and genome‐wide DNA‐binding profiles were generated to assess the chromatin of HSF family members with distinct responses to heat stress. We observed significant variability for both chromatin accessibility and promoter occupancy within similarly regulated sets of HSFs betweenSetariaand maize, as well as between syntenic pairs of maize HSFs retained following its most recent genome duplication event. Additionally, we observed the widespread presence of TF binding at HSF promoters in control conditions, even at HSFs that are only expressed in response to heat stress. TF‐binding peaks were typically near putative HSF‐binding sites in HSFs upregulated in response to heat stress, but not in stable or not expressed HSFs. These observations collectively support a complex scenario of expansion and subfunctionalization within this transcription factor family and suggest that within‐family HSF transcriptional regulation is a conserved, defining feature of the family.

A central problem in speciation is the origin and mechanisms of reproductive barriers that block gene flow between sympatric populations. Wind-pollinated plant species that flower in synchrony with one another rely on post-pollination interactions to maintain reproductive isolation. In some locations in Mexico, sympatric populations of domesticated maize and annual teosinte grow in intimate associate and flower synchronously, but rarely produce hybrids. This trait is typically conferred by a single haplotype,Teosinte crossing barrier1-s. Here, we show that theTeosinte crossing barrier1-shaplotype contains a pistil-expressed, potential speciation gene, encoding a pectin methylesterase homolog. The modification of the pollen tube cell wall by the pistil, then, is likely a key mechanism for pollen rejection inZeaand may represent a general mechanism for reproductive isolation in grasses.

Plant breeders have developed crop plants that are resistant to pests, but the continual evolution of pathogens creates the need to iteratively develop new control strategies. Molecular tools have allowed us to gain deep insights into disease responses, allowing for more efficient, rational engineering of crops that are more robust or resistant to a greater number of pathogen variants. Here we describe the roles ofSWEETandSTPtransporters, membrane proteins that mediate transport of sugars across the plasma membrane. We discuss how these transporters may enhance or restrict disease through controlling the level of nutrients provided to pathogens and whether the transporters play a role in sugar signaling for disease resistance. This review indicates open questions that require further research and proposes the use of genome editing technologies for engineering disease resistance.