Background: Pitayas are currently attracting considerable interest as a tropical fruit with numerous health benefits. However, as a long-day plant, pitaya plants cannot flower in the winter season from November to April in Hainan, China. To harvest pitayas with high economic value in the winter season, it is necessary to provide supplementary lighting at night to induce flowering. To further explore the molecular regulating mechanisms of flower induction in pitaya plants exposed to supplementary lighting, we used de novo RNA sequencing-based transcriptomic analysis for four stages of pitaya plants subjected to light induction. Results: We assembled 68,113 unigenes in total, comprising 29,782 unigenes with functional annotations in the NR database, 20,716 annotations in SwissProt, 18,088 annotations in KOG, and 11,059 annotations in KEGG. Comparisons between different samples revealed different numbers of significantly differentially expressed genes (DEGs). A number of DEGs involved in energy metabolism-related processes and plant hormone signaling were detected. Moreover, we identified many CONSTANS-LIKE, FLOWERING LOCUS T, and other DEGs involved in the direct regulation of flowering including CDF and TCP, which function as typical transcription factor genes in the flowering process. At the transcriptomic level, we verified 13 DEGs with different functions in the time-course response to light-induced flowering by quantitative reverse-transcription PCR analysis. Conclusions: The identified DEGs may include some key genes controlling the pitaya floral-induction network, the flower induction and development is very complicated, and it involves photoperiod perception and different phytohormone signaling. These findings will increase our understanding to the molecular mechanism of floral regulation of long-day pitaya plants in short-day winter season induced by supplementary lighting.

Potassium (K⁺) is an abundant and important macronutrient for plants. It plays crucial roles in many growth and developmental processes, and growth is inhibited under low −K⁺ conditions. The molecular mechanisms operating under K⁺ starvation have been little reported in banana, which is a non-model plant. We conducted a transcriptome analysis of banana (Musa acuminata L. AAA group, cv. Cavendish) in response to low −K⁺ stress. The phenotypic traits and transcriptomic profiles of banana leaves and roots were compared between low −K⁺ (LK) and normal −K⁺ (NK) groups. The phenotypic parameters for the LK group, including fresh and dry weight, were lower than those for the NK group, which suggested that low −K⁺ stress may inhibit some important metabolic and biosynthetic processes. K⁺ content and biomass were both decreased in the LK group compared to the NK group. Following ribonucleic acid sequencing (RNA-Seq), a total of 26,796 expressed genes were detected in normal −K⁺ leaves (NKL), 27,014 were detected in low −K⁺ leaves (LKL), 29,158 were detected in normal −K⁺ roots (NKR), and 28,748 were detected in low −K⁺ roots (LKR). There were 797 up-regulated differentially expressed genes (DEGs) and 386 down-regulated DEGs in NKL versus LKL, while there were 1917 up-regulated DEGs and 2830 down-regulated DEGs in NKR versus LKR. This suggested that the roots were more sensitive to low −K⁺ stress than the leaves. DEGs related to K⁺ transport and uptake were analyzed in detail. Gene functional classification showed that the expression of genes regarding ABC transporters, protein kinases, transcription factors, and ion transporters were also detected, and may play important roles during K⁺ deficiency.

Background: Canker disease caused byNeoscytalidium dimidiatumis a devastating disease resulting in a major loss to the pitaya industry. However, resistance proteins in plants play crucial roles to against pathogen infection. Among resistance proteins, the leucine-rich repeat (LRR) protein is a major family that plays crucial roles in plant growth, development, and biotic and abiotic stress responses, especially in disease defense.Results: In the present study, a transcriptomics analysis identified a total of 272 LRR genes, 233 of which had coding sequences (CDSs), in the plant pitaya (Hylocereus polyrhizus) in response to fungalNeoscytalidium dimidiatuminfection. These genes were divided into various subgroups based on specific domains and phylogenetic analysis. Molecular characterization, functional annotation of proteins, and an expression analysis of the LRR genes were conducted. Additionally, four LRR genes (CL445.Contig4_All, Unigene28_All, CL28.Contig2_All, and Unigene2712_All, which were selected because they had the four longest CDSs were further assessed using quantitative reverse transcription PCR (qRT-PCR) at different fungal infection stages in different pitaya species (Hylocereus polyrhizusandHylocereus undatus), in different pitaya tissues, and after treatment with salicylic acid (SA), methyl jasmonate (MeJA), and abscisic acid (ABA) hormones. The associated protein functions and roles in signaling pathways were identified.Conclusions: This study provides a comprehensive overview of theHpLRR family genes at transcriptional level in pitaya in response toN. dimidiatuminfection, it will be helpful to understand the molecular mechanism of pitaya canker disease, and lay a strong foundation for further research.

Bananas are an important part of the diets of millions of people around the globe. Low P absorption and use efficiency significantly restrict banana yields. To further explore the molecular mechanisms of P regulation in banana plants, we used RNA sequencing-based transcriptomic analysis for banana plants subjected to Pi deficit stress for 60 days. We detected 1900 significantly differentially expressed genes (DEGs) in aboveground plant parts and 7398 DEGs in root parts under low P stress. Gene ontology (GO) classification analysis showed that 156,291 GO terms belonging to molecular functions, 53,114 GO terms belonging to cellular components, and 228,544 GO terms belonging to biological processes were enriched in the aboveground and root components. A number of DEGs involved in energy metabolism-related processes, signal transduction, control of rhizosphere P activation, and Pi mobilization were found, which were confirmed by quantitative reverse-transcription Polymerase Chain Reaction (qRT-PCR) analysis. At the transcriptomic level, we detected 13 DEGs from different organs and with different functions in the time-course response to phosphorus deficiency stress. These DEGs may include some key genes that regulate the phosphorus network, increasing our understanding of the molecular mechanism of Pi homeostasis in banana. These findings will also help develop biotechnologies to create a variant of banana with more effective Pi absorption and utilization.