Root-shoot communications play important roles in plant stress responses. Here, we examined the roles of root-sourced signals in the shoot response to heat in cucumber plants. Cucumber plants grafted onto their own roots and luffa roots were exposed to aerial and root-zone heat to examine their tolerance by assessing the levels of oxidative stress, PSII photoinhibition, accumulation of abscisic acid (ABA), H2 O2 and heat shock protein (HSP) 70 using immunoblotting, chlorophyll fluorescence, immunoassay, CeCl3 staining and Western blotting, respectively. Grafting onto the luffa rootstock enhanced the shoot tolerance to the heat. This enhanced tolerance was associated with increased accumulation of ABA and apoplastic H2 O2 , RBOH transcripts and HSP70 expression and a decrease in oxidative stress in the shoots. The increases in the ABA and H2 O2 concentrations in the shoots were attributed to an increase in ABA transport from roots and an increase in ABA biosynthesis in the shoots when the root-zone and shoots were heat stressed, respectively. Inhibition of H2 O2 accumulation compromised luffa rootstock-induced HSP70 expression and heat tolerance. These results suggest that, under heat stress, ABA triggers the expression of HSP70 in an apoplastic H2 O2 -dependent manner, implicating the role of an ABA-dependent H2 O2 -driven mechanism in a systemic response involving root-shoot communication.

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Reproductive ability, especially prolificacy, impacts sheep profitability. Hu sheep, a unique Chinese breed, is recognized for its high prolificacy (HP), early sexual maturity, and year-round estrus. However, little is known about the molecular mechanisms underlying HP in Hu sheep. To explore the potential mRNAs and long non-coding RNAs (lncRNAs) involved in Hu sheep prolificacy, we performed an ovarian genome-wide analysis of mRNAs and lncRNAs during the follicular stage using Hu sheep of HP (litter size = 3; three consecutive lambings) and low prolificacy (LP, litter size = 1; three consecutive lambings). Plasma luteinizing hormone (LH) concentration was higher in the HP group than in the LP group (P<0.05) during the follicular stage. Subsequently, 76 differentially expressed mRNAs (DE-mRNAs) and five differentially expressed lncRNAs (DE-lncRNAs) were identified by pairwise comparison; quantitative real-time PCR (qRT-PCR) analysis of ten randomly selected DE genes (mRNA and lncRNA) were consistent with the sequencing results. Gene Ontology (GO) analysis of DE-mRNAs revealed significant enrichment in immune response components, actin filament severing and phagocytosis. Pathway enrichment analysis of DE-mRNAs indicated a predominance of immune function pathways, including phagosomes, lysosomes, and antigen processing. We constructed a co-expression network of DE-mRNAs and mRNA-lncRNAs, with C1qA, CD53, cathepsin B (CTSB), CTSS, TYROBP, and AIF1 as the hub genes. Finally, the expression of lysosomal protease cathepsin genes, CTSB and cathepsin D (CTSD), were significantly up-regulated in sheep ovaries in the HP group compared with the LP group (P<0.05). These differential mRNAs and lncRNAs may provide information on the molecular mechanisms underlying sheep prolificacy.

BackgroundOvulation rate and litter size are important reproductive traits in sheep with high economic value. Recent work has revealed a potential link between DNA methylation and prolificacy. However, a genome-wide study that sought to identify potential DNA methylation sites involved in sheep prolificacy indicated that it is still unknown. Here, we aimed to investigate the genome-wide DNA methylation profiles of Hu sheep ovaries by comparing a high-prolificacy group (HP, litter size of three for at least 2 consecutive lambings) and low prolificacy group (LP, litter size of one for at least 2 consecutive lambings) using deep whole-genome bisulfite sequencing (WGBS).ResultsFirst, our results demonstrated lower expression levels of DNA methyltransferase (DNMT) genes in the ovaries of the HP group than that in the ovaries of the LP group. Both groups showed similar proportions of methylation at CpG sites but different proportions at non-CpG sites. Subsequently, we identified 70,899 differential methylated regions (DMRs) of CG, 16 DMRs of CHG, 356 DMRs of CHH and 12,832 DMR-related genes(DMGs). Gene Ontology (GO) analyses revealed that some DMGs were involved in regulating female gonad development and ovarian follicle development. Finally, we found that 10 DMGs, including BMP7, BMPR1B, CTNNB1, FST, FSHR, LHCGR, TGFB2 and TGFB3, are more likely to be involved in prolificacy of Hu sheep, as assessed by correlation analysis and listed in detail.ConclusionsThis study revealed the global DNA methylation pattern of sheep ovaries associated with high and low prolificacy groups, which may contribute to a better understanding of the epigenetic regulation of sheep reproductive capacity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-4068-9) contains supplementary material, which is available to authorized users.

A nutrient solution experiment was conducted to determine the influence of N forms on growth, oxidative stress, and Cd and N uptake in rice plants. The treatments were consisted of two Cd levels (0 and 1 lmol) and three N forms (NH 4 ) 2 SO 4 , NH 4 NO 3 and Ca(NO 3 ) 2 . The results indicated that without Cd addition in the culture solution, the N forms had no significant effect on all measured parameters, including plant growth, photosynthetic traits, malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and Cd and N concentration, while Cd addition in the medium resulted in significant differences in measured parameters among the three forms of N fertilizers. The least inhibition of growth was noted in (NH 4 ) 2 SO 4 -fed plants, and the largest in Ca(NO 3 ) 2 -fed plants, when plants were exposed to Cd stress. The highest photosynthetic rate and chlorophyll content was also recorded in (NH 4 ) 2 SO 4 -fed plants. Addition of Cd caused a remarkable increase in SOD activity and MDA content in plants, and the extent of increase varied with N form, with (NH 4 ) 2 SO 4 -fed plants being smallest. In comparison with the control plants, the N concentration in roots and shoots was not significantly affected in (NH 4 ) 2 SO 4 -fed plants, but significant decrease in root N concentration was found for the NH 4 NO 3 and Ca(NO 3 ) 2 -fed plants under Cd stress. Moreover, the significant differences were also noted among the three N forms in both root and shoot Cd concentrations, with (NH 4 ) 2 SO 4 -fed plants being the lowest. The results indicated that the toxic effect of Cd on rice varied with the form of N fertilizer.

Shoot-root communication is involved in plant stress responses, but its mechanism is largely unknown. To determine the role of roots in stress tolerance, cucumber (Cucumis sativus) shoots from plants with roots of their own or with figleaf gourd (Cucurbita ficifolia, a chilling-tolerant species) or luffa (Luffa cylindrica (L.) M. Roem., a heat-tolerant species) rootstocks were exposed to low (18/13°C), optimal (27/22°C) and high (36/31°C) temperatures, respectively. Grafting onto figleaf gourd and luffa rootstocks significantly alleviated chilling and heat-induced reductions, respectively, in biomass production and CO(2) assimilation capacity in the shoots, while levels of lipid peroxidation and protein oxidation were decreased. Figleaf gourd and luffa rootstocks upregulated a subset of stress-responsive genes involved in signal transduction (MAPK1 and RBOH), transcriptional regulation (MYB and MYC), protein protection (HSP45.9 and HSP70), the antioxidant response (Cu/Zn-SOD, cAPX and GR), and photosynthesis (RBCL, RBCS, RCA and FBPase) at low and high growth temperatures, respectively, and this was accompanied by increased activity of the encoded enzymes and reduced glutathione redox homeostasis in the leaves. Moreover, Heat Shock Protein 70 (HSP70) expression in cucumber leaves was strongly induced by the luffa rootstock at the high growth temperature but slightly induced by the figleaf gourd rootstock at low or high growth temperatures. These results indicate that rootstocks could induce significant changes in the transcripts of stress-responsive and defense-related genes, and the ROS scavenging activity via unknown signals, especially at stressful growth temperatures, and this is one of mechanisms involved in the grafting-induced stress tolerance.

Spermatogenesis can be affected by nutrition, which operates through normal physiological processes by changing the testicular mass and hormone levels profoundly. However, little is known regarding how testis development is regulated by long noncoding RNA (lncRNA). In this study, we investigated the effects of high-grain (HG) feeding on testis development during sexual maturation mediated by lncRNA. The HG diet group showed an increase in growth hormone (GH), insulin-like growth factor-1 (IGF-1) and testosterone (T) levels, and in the number of sperm in the seminiferous tubules compared with the hay-fed group (p < 0.05). Moreover, we found 59 differentially expressed (DE) lncRNAs and 229 DE mRNAs in sheep testis between the two groups. qRT-PCR results of 20 randomly selected DE lncRNAs and mRNAs were also consistent with the RNA-seq data. Through functional enrichment analysis and lncRNA-mRNA interaction network analysis, we screened several lncRNAs that may be enriched for male reproduction such as spermatogenesis, sperm motility, steroid hormones, MAPK and ErbB signaling pathways. This study provides a first insight into the development of the testis with HG feeding in sheep and shows that these changes are associated with alterations in lncRNA expression.In the current intensive sheep production system in China, most rams are fed high-energy diets after sexual maturation, in order to maximize their body weight gain. High-energy diets with adequate protein, vitamins, and minerals may also hasten testis development and spermatogenesis 1 . However, the process of spermatogenesis is complicated and involves strict developmental regulations at both the transcriptional and the post-transcriptional level 2 . It is difficult to have a thorough understanding of the effects of nutrition on spermatogenesis. Among the regulators of spermatogenesis, recent years researchers have shifted their focus to post-transcriptional control mediated by noncoding RNAs (ncRNAs), which has emerged as an important regulator of spermatogenesis. The ncRNAs such as microRNA (miRNA) 3,4 , PIWI-interacting RNA (piRNA) 5,6 , small interfering RNA (siRNA) 7 and lncRNA 8-10 are known to play regulatory role in male germ cell development. Evidence revealed that the reductions in spermatozoal quality induced by under-nutrition were mediated by changes in expression of miRNAs and piRNAs 11 . A recent study also found miRNAs were involved in sheep abnormal reproductive morphology, apoptosis and male infertility response to under-nutrition 12 . Despite the findings, the understanding of how ncRNAs associated with effects of nutrition on spermatogenesis in the adult testis remains limited.The lncRNAs are one of the most abundant ncRNA families which are more than 200 nucleotides in length. Studies have demonstrated lncRNAs as a new regulatory molecule are involved in mammalian development 13,14 . Recently, many lncRNAs have been identified in specific developmental stages of testes and spermatogenesis in mouse, rat and human models. They are predicte...