Uncovering the basis of small-molecule hormone receptors’ evolution is paramount to a complete understanding of how protein structure drives function. In plants, hormone receptors for strigolactones are well suited to evolutionary inquiries because closely related homologs have different ligand preferences. More importantly, because of facile plant transgenic systems, receptors can be swapped and quickly assessed functionally in vivo. Here, we show that only three mutations are required to turn the nonstrigolactone receptor, KAI2, into a receptor that recognizes the plant hormone strigolactone. This modified receptor still retains its native function to perceive KAI2 ligands. Our directed evolution studies indicate that only a few keystone mutations are required to increase receptor promiscuity of KAI2, which may have implications for strigolactone receptor evolution in parasitic plants.
This article examined the hypothesis that resilience mediates the relationship between marital satisfaction and a host of relevant variables, including spousal attachment, social support, and affect. Participants were 195 married individuals, who completed online surveys about their marriage. Importantly, the findings indicated that resilience has a direct effect on marital satisfaction. In addition, affect and social support were each shown to indirectly impact satisfaction through resilience. The relationships between spousal attachment, resilience, and satisfaction were more complicated than predicted and are further discussed. Overall, the results demonstrate the importance of resilience in marital satisfaction.
Summary
Parasites have evolved proteins, virulence factors (VFs), that facilitate plant colonisation, however VFs mediating parasitic plant–host interactions are poorly understood. Striga hermonthica is an obligate, root‐parasitic plant of cereal hosts in sub‐Saharan Africa, causing devastating yield losses. Understanding the molecular nature and allelic variation of VFs in S. hermonthica is essential for breeding resistance and delaying the evolution of parasite virulence.
We assembled the S. hermonthica genome and identified secreted proteins using in silico prediction. Pooled sequencing of parasites growing on a susceptible and a strongly resistant rice host allowed us to scan for loci where selection imposed by the resistant host had elevated the frequency of alleles contributing to successful colonisation.
Thirty‐eight putatively secreted VFs had very different allele frequencies with functions including host cell wall modification, protease or protease inhibitor and kinase activities. These candidate loci had significantly higher Tajima's D than the genomic background, consistent with balancing selection.
Our results reveal diverse strategies used by S. hermonthica to overcome different layers of host resistance. Understanding the maintenance of variation at virulence loci by balancing selection will be critical to managing the evolution of virulence as part of a sustainable control strategy.
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