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.
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.
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