Significance Citrus bacterial canker, which is caused by several species in the genus Xanthomonas , is a severe disease with worldwide distribution affecting all the commercially important citrus species and cultivars. The mechanisms of canker development, involving erumpent pustule formation and bacterial growth, are not known. Our findings suggest that virulence determinants in several pathogens activate a single host disease susceptibility (S) gene that has a critical contribution to bacterial growth and host pustule development. The S gene represents an excellent candidate for control measures for the citrus bacterial canker.

Piezoelectric materials have been widely used for sensors, actuators, electronics, and energy conversion. Two-dimensional (2D) ultrathin semiconductors, such as monolayer h-BN and MoS with their atom-level geometry, are currently emerging as new and attractive members of the piezoelectric family. However, their piezoelectric polarization is commonly limited to the in-plane direction of odd-number ultrathin layers, largely restricting their application in integrated nanoelectromechanical systems. Recently, theoretical calculations have predicted the existence of out-of-plane and in-plane piezoelectricity in monolayer α-InSe. Here, we experimentally report the coexistence of out-of-plane and in-plane piezoelectricity in monolayer to bulk α-InSe, attributed to their noncentrosymmetry originating from the hexagonal stacking. Specifically, the corresponding d piezoelectric coefficient of α-InSe increases from 0.34 pm/V (monolayer) to 5.6 pm/V (bulk) without any odd-even effect. In addition, we also demonstrate a type of α-InSe-based flexible piezoelectric nanogenerator as an energy-harvesting cell and electronic skin. The out-of-plane and in-plane piezoelectricity in α-InSe flakes offers an opportunity to enable both directional and nondirectional piezoelectric devices to be applicable for self-powered systems and adaptive and strain-tunable electronics/optoelectronics.

No abstract

Key message A high-resolution genetic map combined with haplotype analyses identified a wheat ortholog of rice gene APO1 as the best candidate gene for a 7AL locus affecting spikelet number per spike. Abstract A better understanding of the genes controlling differences in wheat grain yield components can accelerate the improvements required to satisfy future food demands. In this study, we identified a promising candidate gene underlying a quantitative trait locus (QTL) on wheat chromosome arm 7AL regulating spikelet number per spike (SNS). We used large heterogeneous inbred families ( > 10,000 plants) from two crosses to map the 7AL QTL to an 87-kb region (674,019,191–674,106,327 bp, RefSeq v1.0) containing two complete and two partial genes. In this region, we found three major haplotypes that were designated as H1, H2 and H3. The H2 haplotype contributed the high-SNS allele in both H1 × H2 and H2 × H3 segregating populations. The ancestral H3 haplotype is frequent in wild emmer (48%) but rare (~ 1%) in cultivated wheats. By contrast, the H1 and H2 haplotypes became predominant in modern cultivated durum and common wheat, respectively. Among the four candidate genes, only TraesCS7A02G481600 showed a non-synonymous polymorphism that differentiated H2 from the other two haplotypes. This gene, designated here as WHEAT ORTHOLOG OF APO1 ( WAPO1 ), is an ortholog of the rice gene ABERRANT PANICLE ORGANIZATION 1 ( APO1 ), which affects spikelet number. Taken together, the high-resolution genetic map, the association between polymorphisms in the different mapping populations with differences in SNS, and the known role of orthologous genes in other grass species suggest that WAPO-A1 is the most likely candidate gene for the 7AL SNS QTL among the four genes identified in the candidate gene region. Electronic supplementary material The online version of this article (10.1007/s00122-019-03382-5) contains supplementary material, which is available to authorized users.