The complete mitochondrial genome of Paegniodes cupulatus (Ephemeroptera: Heptageniidae), which is sequenced for the first time here, is 15,715 bp in length, containing 13 protein-coding genes, 2 rRNAs, 22 tRNAs and a control region. The overall base composition of the genome is 33.1% for T, 20.7% for C, 32.5% for A and 13.7% for G, with an AT bias of 65.6%.

Key message The cucumber male sterility gene ms - 3 was fine mapped in a 76 kb region harboring an MMD1 -like gene Csa3M006660 that may be responsible for the male sterile in cucumber.AbstractA cucumber (Cucumis sativus L.) male sterile mutant (ms-3) in an advanced-generation inbred line was identified, and genetic analysis revealed that the male sterility trait was controlled by a recessive nuclear gene, ms-3, which was stably inherited. Histological studies suggested that the main cause of the male sterility was defective microsporogenesis, resulting in no tetrad or microspores being formed. Bulked segregant analysis (BSA) and genotyping of an F2 population of 2553 individuals were employed used to fine map ms-3, which was delimited to a 76 Kb region. In this region, a single non-synonymous SNP was found in the Csa3M006660 gene locus, which was predicted to result in an amino acid change. Quantitative RT-PCR analysis of Csa3M006660 was consistent with the fact that it plays a role in the early development of cucumber pollen. The protein encoded by Csa3M006660 is predicted to be homeodomain (PHD) finger protein, and the high degree of sequence conservation with homologs from a range of plant species further suggested the importance of the ms-3 non-synonymous mutation. The data presented here provide support for Csa3M006660 as the most likely candidate gene for Ms-3.Electronic supplementary materialThe online version of this article (10.1007/s00122-017-3013-2) contains supplementary material, which is available to authorized users.

Cucumbers are one of the most important vegetable crops worldwide. The molecular markers have substantial potential to improve the efficiency of conventional cucumber breeding. In this study, a total of 101 157 simple sequence repeats (SSRs) were identified across the cucumber 9930 genome. Most (69 526 of 76 103 or 91.36%) SSRs with unique flanking sequences (unique SSRs) had polymorphisms among 103 cucumber genomes; the number of alleles ranged from 2 to 34 with an average of 4.70. Next, we selected 7486 unique SSR loci with polymorphism information content (PIC) ≥0.5 and major allele differences (the size difference between the alleles with the highest and the second highest frequency) ≥3 bp to design primers. The SSR marker polymorphisms were experimentally validated; 50 highly polymorphic SSR markers had polymorphisms with an average PIC of 0.44. PCR analysis also indicated that these SSR markers could be effectively used as molecular markers. The SSR fingerprints and polymorphic SSR markers with large major allele differences could enhance the efficiency of genetic research and marker‐assisted breeding in cucumbers.

Cucumber () pollen development involves a diverse range of gene interactions between sporophytic and gametophytic tissues. Previous studies in our laboratory showed that male sterility was controlled by a single recessive nuclear gene, and occurred in pollen mother cell meiophase. To fully explore the global gene expression and identify genes related to male sterility, a RNA-seq analysis was adopted in this study. Young male flower-buds (1-2 mm in length) from genetic male sterility (GMS) mutant and homozygous fertile cucumber (WT) were collected for two sequencing libraries. Total 545 differentially expressed genes (DEGs), including 142 up-regulated DEGs and 403 down-regulated DEGs, were detected in two libraries (Fold Change ≥ 2, FDR < 0.01). These genes were involved in a variety of metabolic pathways, like ethylene-activated signaling pathway, sporopollenin biosynthetic pathway, cell cycle and DNA damage repair pathway. qRT-PCR analysis was performed and showed that the correlation between RNA-Seq and qRT-PCR was 0.876. These findings contribute to a better understanding of the mechanism that leads to GMS in cucumber.

No abstract