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Martensitic transformation, usually accompanied by ferroelastic and thermoelastic behaviors, is an interesting and useful mechanical-related property upon external stimuli. For molecular crystals, however, martensitic systems to show reversible stimuli-actuation behaviors are still limited because of a lack of designability and frequent crystal collapse due to large stress releases during the transformations. Here, a one-dimensional hybrid perovskite semiconductor (NMEA)PbI3 (NMEA = N-methylethylammonium) was prepared by following a dimensionality reduction design principle. The crystal undergoes reversible ferroelastic and thermoelastic martensitic transformations, which are attributed to weak intermolecular interactions among the chains that easily trigger the interchain shearing movement. The actuation behavior occurring during the phase transition is very close to room temperature and demonstrated to behave as a mechanical actuator for switching. This work provides an effective approach to designing molecular actuators with promising applications in next-generation intelligence devices.

Non-random gene organization in eukaryotes plays a significant role in genome evolution. Here, we investigate the origin of a biosynthetic gene cluster for production of defence compounds in oat—the avenacin cluster. We elucidate the structure and organisation of this 12-gene cluster, characterise the last two missing pathway steps, and reconstitute the entire pathway in tobacco by transient expression. We show that the cluster has formed de novo since the divergence of oats in a subtelomeric region of the genome that lacks homology with other grasses, and that gene order is approximately colinear with the biosynthetic pathway. We speculate that the positioning of the late pathway genes furthest away from the telomere may mitigate against a ‘self-poisoning’ scenario in which toxic intermediates accumulate as a result of telomeric gene deletions. Our investigations reveal a striking example of adaptive evolution underpinned by remarkable genome plasticity., The genomic organization and origin of the avenacin biosynthetic gene cluster remain unknown. Here, the authors assemble the genome of diploid oat Avena strigosa, reveal the structure and organization of the consecutive genes, characterize the last two missing pathway steps, and investigate the origin of the pathway in cereals.

Miscanthus, a rhizomatous perennial plant, has great potential for bioenergy production for its high biomass and stress tolerance. We report a chromosome-scale assembly of Miscanthus lutarioriparius genome by combining Oxford Nanopore sequencing and Hi-C technologies. The 2.07-Gb assembly covers 96.64% of the genome, with contig N50 of 1.71 Mb. The centromere and telomere sequences are assembled for all 19 chromosomes and chromosome 10, respectively. Allotetraploid origin of the M. lutarioriparius is confirmed using centromeric satellite repeats. The tetraploid genome structure and several chromosomal rearrangements relative to sorghum are clearly demonstrated. Tandem duplicate genes of M. lutarioriparius are functional enriched not only in terms related to stress response, but cell wall biosynthesis. Gene families related to disease resistance, cell wall biosynthesis and metal ion transport are greatly expanded and evolved. The expansion of these families may be an important genomic basis for the enhancement of remarkable traits of M. lutarioriparius., The genus Miscanthus has great potential for bio-energy production due to its high biomass yield and strong stress resistance. Here, the authors report the genome assembly of the diploid M. lutarioriparius, showing it has an allotetraploid origin and an expanded number of genes in families related to stress resistance.

High strength and high ductility are often mutually exclusive properties for structural metallic materials. This is particularly important for aluminum (Al)-based alloys which are widely commercially employed. Here, we introduce a hierarchical nanostructured Al alloy with a structure of Al nanograins surrounded by nano-sized metallic glass (MG) shells. It achieves an ultrahigh yield strength of 1.2 GPa in tension (1.7 GPa in compression) along with 15% plasticity in tension (over 70% in compression). The nano-sized MG phase facilitates such ultrahigh strength by impeding dislocation gliding from one nanograin to another, while continuous generation-movement-annihilation of dislocations in the Al nanograins and the flow behavior of the nano-sized MG phase result in increased plasticity. This plastic deformation mechanism is also an efficient way to decrease grain size to sub-10 nm size for low melting temperature metals like Al, making this structural design one solution to the strength-plasticity trade-off., Strengthening a metallic alloy without sacrificing ductility remains challenging. Here, the authors develop a hierarchical nanostructured aluminium alloy composed of nanograins surrounding by metallic glass shells that has both ultrahigh strength and good ductility.

Today East Asia harbors many “relict” plant species whose ranges were much larger during the Paleogene-Neogene and earlier. The ecological and climatic conditions suitable for these relict species have not been identified. Here, we map the abundance and distribution patterns of relict species, showing high abundance in the humid subtropical/warm-temperate forest regions. We further use Ecological Niche Modeling to show that these patterns align with maps of climate refugia, and we predict species’ chances of persistence given the future climatic changes expected for East Asia. By 2070, potentially suitable areas with high richness of relict species will decrease, although the areas as a whole will probably expand. We identify areas in southwestern China and northern Vietnam as long-term climatically stable refugia likely to preserve ancient lineages, highlighting areas that could be prioritized for conservation of such species., We acknowledge funding by the Global Environmental Research (S-14) of the Ministry of the Environment (Japan), the Proyecto Intramural Especial, PIE (grant no. 201630I024) from the CSIC, Spain, the Natural Science Foundation Project of CQ CSTC (cstc2016jcyjA0379) (China), and the Northeastern Research Institute of Petrified Wood and Mineral Resources, Nakhon Ratchasima Rajabhat University (Thailand).

Pollution by heavy metals limits the area of land available for cultivation of food crops. A potential solution to this problem might lie in the molecular breeding of food crops for phytoremediation that accumulate toxic metals in straw while producing safe and nutritious grains. Here, we identify a rice quantitative trait locus we name cadmium (Cd) accumulation in leaf 1 (CAL1), which encodes a defensin-like protein. CAL1 is expressed preferentially in root exodermis and xylem parenchyma cells. We provide evidence that CAL1 acts by chelating Cd in the cytosol and facilitating Cd secretion to extracellular spaces, hence lowering cytosolic Cd concentration while driving long-distance Cd transport via xylem vessels. CAL1 does not appear to affect Cd accumulation in rice grains or the accumulation of other essential metals, thus providing an efficient molecular tool to breed dual-function rice varieties that produce safe grains while remediating paddy soils., Crops that allocate heavy metals to leaves rather than grains could allow phytoremediation of polluted soil while producing food that is safe to eat. Here, the authors show that a defensin-like protein promotes cadmium secretion from rice cells and allocation to leaves without causing accumulation in grain.

Super hybrid rice varieties with ideal plant architecture (IPA) have been critical in enhancing food security worldwide. However, the molecular mechanisms underlying their improved yield remain unclear. Here, we report the identification of a QTL, qWS8/ipa1-2D, in the super rice Yongyou12 (YY12) and related varieties. In-depth genetic molecular characterization of qWS8/ipa1-2D reveals that this newly identified QTL results from three distal naturally occurring tandem repeats upstream of IPA1, a key gene/locus previously shown to shape rice ideal plant architecture and greatly enhance grain yield. The qWS8/ipa1-2D locus is associated with reduced DNA methylation and a more open chromatin state at the IPA1 promoter, thus alleviating the epigenetic repression of IPA1 mediated by nearby heterochromatin. Our findings reveal that IPA traits can be fine-tuned by manipulating IPA1 expression and that an optimal IPA1 expression/dose may lead to an ideal yield, demonstrating a practical approach to efficiently design elite super rice varieties., Breeding of rice with ideal plant architecture has increased rice yield worldwide. Here Zhang et al. show that, in the super rice variety YY12, this ideal plant architecture trait arose from three distal tandem repeats that are associated with an open chromatin state and increased expression of the IPA1 gene.

Hybrid rice breeding for exploiting hybrid vigor, heterosis, has greatly increased grain yield. However, the heterosis-related genes associated with rice grain production remain largely unknown, partly because comprehensive mapping of heterosis-related traits is still labor-intensive and time-consuming. Here, we present a quantitative trait locus (QTL) mapping method, GradedPool-Seq, for rapidly mapping QTLs by whole-genome sequencing of graded-pool samples from F2 progeny via bulked-segregant analysis. We implement this method and map-based cloning to dissect the heterotic QTL GW3p6 from the female line. We then generate the near isogenic line NIL-FH676::GW3p6 by introgressing the GW3p6 allele from the female line Guangzhan63-4S into the male inbred line Fuhui676. The NIL-FH676::GW3p6 exhibits grain yield highly increased compared to Fuhui676. This study demonstrates that it may be possible to achieve a high level of grain production in inbred rice lines without the need to construct hybrids., Developing hybrid rice cultivars requires time consuming random crossing. Here, the authors develop a new next generation sequencing-based quantitative trait locus mapping method to dissect heterotic gene OsMADS1 and demonstrate the feasibility of pyramiding two genes to achieve large heterotic effect.

In the original version of this Article, an incorrect sample size was provided for the number of relict species (443 instead of 442) and the number of relict forests (423 instead of 422). These errors have been corrected in both the PDF and HTML versions of the Article.

Oilseed crops are used to produce vegetable oil. Sesame (Sesamum indicum), an oilseed crop grown worldwide, has high oil content and a small diploid genome, but the genetic basis of oil production and quality is unclear. Here we sequence 705 diverse sesame varieties to construct a haplotype map of the sesame genome and de novo assemble two representative varieties to identify sequence variations. We investigate 56 agronomic traits in four environments and identify 549 associated loci. Examination of the major loci identifies 46 candidate causative genes, including genes related to oil content, fatty acid biosynthesis and yield. Several of the candidate genes for oil content encode enzymes involved in oil metabolism. Two major genes associated with lignification and black pigmentation in the seed coat are also associated with large variation in oil content. These findings may inform breeding and improvement strategies for a broad range of oilseed crops., Sesame is a valuable oilseed crop with a small diploid genome and high seed-oil content making it an attractive model for genetic studies. Here, Wei et al. sequence more than 705 sesame varieties and perform a genome-wide association study to identify genes associated with important agronomic traits.

Reproductive barriers perform a vital role during speciation. Hybrid weakness, the poorer development of hybrids compared with their parents, hinders gene exchange between different species at the postzygotic stage. Here we show that two incompatible dominant loci (Hwi1 and Hwi2) involving three genes are likely to determine the high temperature-dependent expression of hybrid weakness in interspecific hybrids of rice. Hwi1 comprises two leucine-rich repeat receptor-like kinase (LRR–RLK) genes, 25L1 and 25L2, which are specific to wild rice (Oryza rufipogon) and induce hybrid weakness. Hwi2, a rare allele that is predominantly distributed in indica rice (Oryza sativa), encodes a secreted putative subtilisin-like protease. Functional analysis indicated that pyramiding of Hwi1 and Hwi2 activates the autoimmune response in the basal nodes of hybrids, interrupting root formation and then impairing shoot growth. These findings bring new insights into our understanding of reproductive isolation and may benefit rice breeding., Hybrids often show poorer performance than their parents due to conflict between parental genes, but the underlying mechanisms are not well understood. Here, Chen et al. identify three genes that activate immune responses and hinder hybrids growth in rice, a finding that may help rice breeding.