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SUMMARY: Grasses derive from a family of monocotyledonous plants that includes crops of major economic importance such as wheat, rice, sorghum and barley, sharing a common ancestor some 100 million years ago. The genomic attributes of plant adaptation remain obscure and the consequences of recurrent whole genome duplications (WGD) or polyploidization events, a major force in plant evolution, remain largely speculative. We conducted a comparative analysis of omics data from ten grass species to unveil structural (inversions, fusions, fissions, duplications, substitutions) and regulatory (expression and methylation) basis of genome plasticity, as possible attributes of plant long lasting evolution and adaptation. The present study demonstrates that diverged polyploid lineages sharing a common WGD event often present the same patterns of structural changes and evolutionary dynamics, but these patterns are difficult to generalize across independent WGD events as a result of non‐WGD factors such as selection and domestication of crops. Polyploidy is unequivocally linked to the evolutionary success of grasses during the past 100 million years, although it remains difficult to attribute this success to particular genomic consequences of polyploidization, suggesting that polyploids harness the potential of genome duplication, at least partially, in lineage‐specific ways. Overall, the present study clearly demonstrates that post‐polyploidization reprogramming is more complex than traditionally reported in investigating single species and calls for a critical and comprehensive comparison across independently polyploidized lineages. Significance Statement: The present study investigates the role of genome doubling (polyploidization), a major force in plant evolution, in promoting (gen)omic reprogramming in grasses. [ABSTRACT FROM AUTHOR]

To meet the increasing global demand for food, feed, fibre and other plant‐derived products, a steep increase in crop productivity is a scientifically and technically challenging imperative. The CropBooster‐P project, a response to the H2020 call 'Future proofing our plants', is developing a roadmap for plant research to improve crops critical for the future of European agriculture by increasing crop yield, nutritional quality, value for non‐food applications and sustainability. However, if we want to efficiently improve crop production in Europe and prioritize methods for crop trait improvement in the coming years, we need to take into account future socio‐economic, technological and global developments, including numerous policy and socio‐economic challenges and constraints. Based on a wide range of possible global trends and key uncertainties, we developed four extreme future learning scenarios that depict complementary future developments. Here, we elaborate on how the scenarios could inform and direct future plant research, and we aim to highlight the crop improvement approaches that could be the most promising or appropriate within each of these four future world scenarios. Moreover, we discuss some key plant technology options that would need to be developed further to meet the needs of multiple future learning scenarios, such as improving methods for breeding and genetic engineering. In addition, other diverse platforms of food production may offer unrealized potential, such as underutilized terrestrial and aquatic species as alternative sources of nutrition and biomass production. We demonstrate that although several methods or traits could facilitate a more efficient crop production system in some of the scenarios, others may offer great potential in all four of the future learning scenarios. Altogether, this indicates that depending on which future we are heading toward, distinct plant research fields should be given priority if we are to meet our food, feed and non‐food biomass production needs in the coming decades. [ABSTRACT FROM AUTHOR]

Maize (corn) is one of the most widely grown cereal crops globally. Fungal diseases of maize cause significant economic damage by reducing maize yields and by increasing input costs for disease management. The most sustainable control of maize diseases is through the release and planting of maize cultivars with durable disease resistance. The wheat gene Lr34 provides durable and partial field resistance against multiple fungal diseases of wheat, including three wheat rust pathogens and wheat powdery mildew. Because of its unique qualities, Lr34 became a cornerstone in many wheat disease resistance programmes. The Lr34 resistance is encoded by a rare variant of an ATP-binding cassette ( ABC) transporter that evolved after wheat domestication. An Lr34-like disease resistance phenotype has not been reported in other cereal species, including maize. Here, we transformed the Lr34 resistance gene into the maize hybrid Hi- II. Lr34-expressing maize plants showed increased resistance against the biotrophic fungal disease common rust and the hemi-biotrophic disease northern corn leaf blight. Furthermore, the Lr34-expressing maize plants developed a late leaf tip necrosis phenotype, without negative impact on plant growth. With this and previous reports, it could be shown that Lr34 is effective against various biotrophic and hemi-biotrophic diseases that collectively parasitize all major cereal crop species. [ABSTRACT FROM AUTHOR]

Gynogenesis is an asexual mode of reproduction common to animals and plants, in which stimuli from the sperm cell trigger the development of the unfertilized egg cell into a haploid embryo. Fine mapping restricted a major maize QTL (quantitative trait locus) responsible for the aptitude of inducer lines to trigger gynogenesis to a zone containing a single gene NOT LIKE DAD ( NLD) coding for a patatin-like phospholipase A. In all surveyed inducer lines, NLD carries a 4-bp insertion leading to a predicted truncated protein. This frameshift mutation is responsible for haploid induction because complementation with wild-type NLD abolishes the haploid induction capacity. Activity of the NLD promoter is restricted to mature pollen and pollen tube. The translational NLD::citrine fusion protein likely localizes to the sperm cell plasma membrane. In Arabidopsis roots, the truncated protein is no longer localized to the plasma membrane, contrary to the wild-type NLD protein. In conclusion, an intact pollen-specific phospholipase is required for successful sexual reproduction and its targeted disruption may allow establishing powerful haploid breeding tools in numerous crops. [ABSTRACT FROM AUTHOR]

In angiosperm seeds the embryo is embedded within the endosperm, which is in turn enveloped by the seed coat, making inter-compartmental communication essential for coordinated seed growth. In this context the basic helix-loop-helix domain transcription factor At ZHOUPI (At ZOU) fulfils a key role in both the lysis of the transient endosperm and in embryo cuticle formation in Arabidopsis thaliana. In maize ( Zea mays), a cereal with a persistent endosperm, a single gene, Zm ZOU, falls into the same phylogenetic clade as At ZOU. Its expression is limited to the endosperm where it peaks during the filling stage. In Zm ZOU- RNA interference knock-down lines embryo size is slightly reduced and the embryonic suspensor and the adjacent embryo surrounding region show retarded breakdown. Ectopic expression of Zm ZOU reduces stomatal number, possibly due to inappropriate protein interactions. Zm ZOU forms functional heterodimers with At ICE/At SCREAM and the closely related maize proteins Zm ICEb and Zm ICEc, but its interaction is more efficient with the Zm ICEa protein, which shows sequence divergence and only has close homologues in other monocotyledonous species. Consistent with the observation that these complexes can trans-activate target gene promoters from Arabidopsis, Zm ZOU partially complements the Atzou-4 mutant. However, structural, trans-activation and gene expression data support the hypothesis that Zm ZOU and Zm ICEa may have coevolved to form a functional complex unique to monocot seeds. This divergence may explain the reduced functionality of Zm ZOU in Arabidopsis, and reflect functional specificities which are unique to the monocotyledon lineage. [ABSTRACT FROM AUTHOR]

Small non-coding RNAs are versatile riboregulators that control gene expression at the transcriptional or post-transcriptional level, governing many facets of plant development. Here we present evidence for the existence of a 24 nt small RNA (named small1) that is complementary to the 3′ UTR of OCL1 ( Outer Cell Layer1), the founding member of the maize HD- ZIP IV gene family encoding plant-specific transcription factors that are mainly involved in epidermis differentiation and specialization. The biogenesis of small1 depends on DICER-like 3 (DCL3), RNA-dependent RNA polymerase 2 ( RDR2) and RNA polymerase IV, components that are usually required for RNA-dependent DNA-methylation. Unexpectedly, GFP sensor experiments in transient and stable transformation systems revealed that small1 may regulate its target at the post-transcriptional level, mainly through translational repression. This translational repression is attenuated in an rdr2 mutant background in which small1 does not accumulate. Our experiments further showed the possible involvement of a secondary stem-loop structure present in the 3′ UTR of OCL1 for efficient target repression, suggesting the existence of several regulatory mechanisms affecting OCL1 mRNA stability and translation. [ABSTRACT FROM AUTHOR]

Epidermis differentiation and maintenance are essential for plant survival. Constant cross-talk between epidermal cells and their immediate environment is at the heart of epidermal cell fate, and regulates epidermis-specific transcription factors. These factors in turn direct epidermal differentiation involving a whole array of epidermis- specific pathways including specialized lipid metabolism necessary to build the protective cuticle layer. An intact epidermis is crucial for certain key processes in plant development, shoot growth and plant defence. Here, we discuss the control of epidermal cell fate and the function of the epidermal cell layer in the light of recent advances in the field. [ABSTRACT FROM AUTHOR]

Among the genes controlling the differentiation and maintenance of epidermal cell fate are members of the HD-ZIP IV class family of plant-specific transcription factors, most of which are specifically expressed in the epidermis of tissues. Here, we report the functional analysis of the maize HD-ZIP IV gene OCL4 ( outer cell layer 4) via the phenotypic analysis of two insertional mutants, and of OCL4-RNAi transgenic plants. In all three materials, the macrohairs, one of the three types of trichomes present on adult maize leaf blades, developed ectopically at the margin of juvenile and adult leaves. Consistent with this phenotype, OCL4 is expressed in the epidermis of the leaf blade, with a maximum at the margin of young leaf primordia. Expression of OCL4 in the model plant Arabidopsis under the control of the GLABRA2 ( GL2) promoter, a member of the Arabidopsis HD-ZIP IV family involved in trichome differentiation, did not complement the gl2-1 mutant, but instead aggravated its phenotype. The construct also caused a glabrous appearance of rosette leaves in transformed control plants of the L er ecotype, suggesting that OCL4 inhibits trichome development both in maize and Arabidopsis. Furthermore, insertional mutants showed a partial male sterility that is likely to result from the presence of an extra subepidermal cell layer with endothecium characteristics in the anther wall. Interestingly, the epidermis-specific OCL4 expression in immature anthers was restricted to the region of the anther locule where the extra cell layer differentiated. Taken together these results suggest that OCL4 inhibits trichome development and influences division and/or differentiation of the anther cell wall. [ABSTRACT FROM AUTHOR]

Summary A family of homeo box genes with cell layer-specific expression patterns defining subdomains of the embryo and certain meristems has been isolated from maize. These genes encode proteins from the class of plant specific homeo domain-leucine zipper (HD-Zip) transcription factors containing the previously described ZmOCL1 protein, and have been designated ZmOCL2 , ZmOCL3 , ZmOCL4 and ZmOCL5 . ZmOCL3 , ZmOCL4 and ZmOCL5 , like ZmOCL1 , showed essentially L1 or epidermis-specific expression. However, each gene was expressed in a distinct region of the embryonic protoderm during early development, with ZmOCL3 showing suspensor-specific expression, ZmOCL4 transcripts being localized to the adaxial face of the embryo proper and ZmOCL5 showing a more abaxial expression pattern. All three genes were also expressed in vegetative, inflorescence and floral apices, although ZmOCL3 transcripts were excluded from meristems and very young organ primordia. In contrast, ZmOCL2 expression was entirely meristem-specific and was excluded from the L1 layer, appearing instead to be largely restricted to a cell layer directly beneath the L1, especially in floral meristems. This expression pattern is unprecedented and may indicate that cell-layer organization in maize meristems is more complex than that suggested by the classical L1/L2 (outer cell layer/inner cell mass) model. These differing expression patterns indicate that the members of the HD-ZipIV family of maize may not only play roles in defining different regions of the epidermis during embryonic development, but could also be responsible for maintaining cell-layer identity in meristematic regions. [ABSTRACT FROM AUTHOR]

We have determined the complete nucleotide sequence of a 4.8 kilobase fragment encompassing the virA locus of the nopaline-type plasmid, pTiC58, of Agrobacterium tumefaciens. virA is composed of a single open reading frame of 2499 nucleotides, capable of encoding a protein of 91.3 kiloDaltons. A trpE::virA gene fusion was used to confirm the reading frame of virA. High nucleotide and amino acid sequence homologies were observed between pTiC58 virA and the virA sequences of three octopine-type plasmids. Strong homologies in amino acid sequence were observed between pTiC58 VirA and seven bacterial proteins which control various regulons. Two hydrophobic domains within VirA are also consistent with a model in which VirA acts as a membrane-bound sensor of plant signal molecules. [ABSTRACT FROM AUTHOR]

Virulence genes of the Agrobacterium tumefaciens Ti plasmid are positively regulated by the products of virA and virG. To study the DNA-binding properties of the VirG protein, a translational fusion between virG and the trpE gene of Escherichia coli was constructed, and antiserum was raised against the encoded fusion protein. Using this antiserum, a protein of Mr = 29000, a size similar to that calculated from the virG nucleotide sequence, was detected in an E. coli strain harbouring a virG expression vector. Both the VirG protein and the fusion protein were found, by filter-binding and gel retardation analyses, to bind DNA nonspecifically. These data support an existing model for the two-component regulatory systems of bacteria. [ABSTRACT FROM AUTHOR]

The nucleotide sequence of the virG locus of the nopaline type plasmid pTiC58 of Agrobacterium tumefaciens has been determined. It contains an open reading frame (ORF) of 759 nucleotides and has 77% homology to the virG sequences of octopine type plasmids. Differences between the sequences of the two types of Ti plasmids in the region of virG are located predominantly outside the ORF. The amino acid sequences inferred from the two virG genes show 60% homology to each other and each shows the same moderate homologies to amino acid sequences derived from genes in a family of two-component regulatory systems. Specific differences in nucleotide and amino acid sequences as well as a structure-function model for the gene product are discussed. [ABSTRACT FROM AUTHOR]

Examines issues related to the application of a competition-oriented approach to multilateral trade negotiations. Overall rationale for a competition-oriented approach; Economic benefits; Criteria that might be applied in selecting topics and establishing an orientation for negotiation under such an approach.

The acute phase response is accompanied by the appearance of aggregated red blood cells in the peripheral blood. The Westergren erythrocyte sedimentation rate (ESR) is an indirect measurement of this enhanced aggregability. We adopted a simple slide test and image analysis to reveal the adhesiveness/aggregation of red blood cells. A significant correlation was found between the erythrocyte adhesiveness/aggregation test (EAAT) and the ESR. A predictive model for ESR based on EAAT and the age of the patients was created. This new approach will enable us to obtain within a few minutes a good estimate of whether a given individual has a mild moderate or significant acute phase response. With further development, we will be able to use a bedside small cartridge that will deliver the extrapolated ESR at low costs and within a couple of minutes. [ABSTRACT FROM AUTHOR]