Floret fertility is a key determinant of the number of grains per inflorescence in cereals. During the evolution of wheat (Triticum sp.), floret fertility has increased, such that current bread wheat (Triticum aestivum) cultivars set three to five grains per spikelet. However, little is known regarding the genetic basis of floret fertility. The locus Grain Number Increase 1 (GNI1) is shown here to be an important contributor to floret fertility. GNI1 evolved in the Triticeae through gene duplication. The gene, which encodes a homeodomain leucine zipper class I (HD-Zip I) transcription factor, was expressed most abundantly in the most apical floret primordia and in parts of the rachilla, suggesting that it acts to inhibit rachilla growth and development. The level of GNI1 expression has decreased over the course of wheat evolution under domestication, leading to the production of spikes bearing more fertile florets and setting more grains per spikelet. Genetic analysis has revealed that the reduced-function allele GNI-A1 contributes to the increased number of fertile florets per spikelet. The RNAi-based knockdown of GNI1 led to an increase in the number of both fertile florets and grains in hexaploid wheat. Mutants carrying an impaired GNI-A1 allele out-yielded WT allele carriers under field conditions. The data show that gene duplication generated evolutionary novelty affecting floret fertility while mutations favoring increased grain production have been under selection during wheat evolution under domestication.

Plants developed various reversible and non‐reversible acclimation mechanisms to cope with the multifaceted nature of abiotic‐stress combinations. We hypothesized that in order to endure these stress combinations, plants elicit distinctive acclimation strategies through specific trade‐offs between reproduction and defense. To investigate Brachypodium distachyon acclimation strategies to combinations of salinity, drought and heat, we applied a system biology approach, integrating physiological, metabolic, and transcriptional analyses. We analyzed the trade‐offs among functional and performance traits, and their effects on plant fitness. A combination of drought and heat resulted in escape strategy, while under a combination of salinity and heat, plants exhibited an avoidance strategy. On the other hand, under combinations of salinity and drought, with or without heat stress, plant fitness (i.e., germination rate of subsequent generation) was severely impaired. These results indicate that under combined stresses, plants’ life‐history strategies were shaped by the limits of phenotypic and metabolic plasticity and the trade‐offs between traits, thereby giving raise to distinct acclimations. Our findings provide a mechanistic understanding of plant acclimations to combinations of abiotic stresses and shed light on the different life‐history strategies that can contribute to grass fitness and possibly to their dispersion under changing environments.

Background Unrevealing the genetic makeup of crop morpho-agronomic traits is essential for improving yield quality and sustainability. Sesame (Sesamum indicum L.) is one of the oldest oil-crops in the world. Despite its economic and agricultural importance, it is an ‘orphan crop-plant’ that has undergone limited modern selection, and, as a consequence preserved wide genetic diversity. Here we established a new sesame panel (SCHUJI) that contains 184 genotypes representing wide phenotypic variation and is geographically distributed. We harnessed the natural variation of this panel to perform genome-wide association studies for morpho-agronomic traits under the Mediterranean climate conditions. Results Field-based phenotyping of the SCHUJI panel across two seasons exposed wide phenotypic variation for all traits. Using 20,294 single-nucleotide polymorphism markers, we detected 50 genomic signals associated with these traits. Major genomic region on LG2 was associated with flowering date and yield-related traits, exemplified the key role of the flowering date on productivity. Conclusions Our results shed light on the genetic architecture of flowering date and its interaction with yield components in sesame and may serve as a basis for future sesame breeding programs in the Mediterranean basin.

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Wheat domestication and subsequent improvement formed a wide phenotypic variation in Grain Weight (GW) between the domesticated wheat species and their wild progenitors. GW continues to be an important goal of many wheat-breeding programs and yet, although studies found many quantitative trait loci (QTLs) for GW, not many genes that underlay these loci were identified. Here we performed QTL analysis for GW using a Recombinant Inbred Line (RIL) population based of a cross between wild emmer wheat accession 'Zavitan' and durum wheat variety 'Svevo'. Using the recent Zavitan genome assembly, we anchored the identified QTLs to the reference sequence and added the positions of previously published QTLs for GW in tetraploid wheat. This genome based meta-QTL analysis enabled us to identify a locus on chromosome 6A with a positive effect on GW that was contributed by wild wheat in a few studies. This locus was validated using an introgression line that contains the 6A GW QTL from Zavitan in the background of Svevo with higher grain weight. Using the reference sequence and genes associated with GW from rice, we were able to identify a wheat ortholog in the 6A QTL region to rice gene, OsGRF4. The coding sequence of this gene, TtGRF4-A, showed four SNPs between Zavitan and Svevo. Molecular marker developed for the first SNP showed that the Zavitan allele of TtGRF4-A is rare in a core collection of wild emmer and absent in domesticated emmer genepool. We suggest that TtGRF4-A is a candidate underlying the 6A GW QTL and breeding with its natural Zavitan allele may have the potential to increase wheat yields. . Faris, J. D.; Zhang, Q.; Chao, S.; Zhang, Z.; Xu, S. S. Analysis of agronomic and domestication traits in a durum × cultivated emmer wheat population using a high-density single nucleotide