Pineapple Fruit Development Research Articles

Genome-wide investigation of sucrose synthase gene family in pineapple: Characterization and expression profile analysis during fruit development

ABSTRACT Sucrose content influences the flavour and quality of fruits. Sucrose synthase (SUS; EC 2.4.1.13) mediates the reversible conversion of uridine diphosphate and sucrose to uridine diphosphate-glucose and fructose. Although genome-wide analyses of SUS gene families exist for various species, such studies are lacking for pineapple. The specific SUS gene(s) involved in sucrose metabolism during pineapple development remain unknown. This study identified six SUS genes (AcSUS1–6) and analysed their chromosomal locations, synteny, structure, motif composition, sequence alignments, and phylogenetic relationships. Gene promoter analysis revealed a predominance of light-response elements in the AcSUS gene family. AcSUS1 was predominantly expressed in the peduncle, pericarp, and core, whereas AcSUS4 was highly expressed in the flesh. The levels of sucrose, glucose, and fructose increase during pineapple fruit development. Further gene expression analysis indicated that AcSUS2, AcSUS3, and AcSUS5 were down-regulated during this period. These results suggest that AcSUS2, AcSUS3, and AcSUS5 may modulate sucrose breakdown in pineapple. This study contributes to our understanding of SUS gene function in regulating sucrose metabolism and offers valuable theoretical guidance for the genetic improvement of pineapples.

Genome-Wide Identification and Expression Patterns of AcSWEET Family in Pineapple and AcSWEET11 Mediated Sugar Accumulation.

Pineapple (Ananas comosus L.) is an important fruit crop in tropical regions, and it requires efficient sugar allocation during fruit development. Sugars Will Eventually be Exported Transporters (SWEETs) are a group of novel sugar transporters which play critical roles in seed and fruit development. However, the function of AcSWEETs remains unknown in the sugar accumulation. Herein, 17 AcSWEETs were isolated and unevenly located in 11 chromosomes. Analysis of a phylogenetic tree indicated that 17 genes were classified into four clades, and the majority of AcSWEETs in each clade shared similar conserved motifs and gene structures. Tissue-specific gene expression showed that expression profiles of AcSWEETs displayed differences in different tissues and five AcSWEETs were strongly expressed during fruit development. AcSWEET11 was highly expressed in the stage of mature fruits in 'Tainong16' and 'Comte de paris', which indicates that AcSWEET11 was important to fruit development. Subcellular localization analysis showed that AcSWEET11 was located in the cell membrane. Notably, overexpression of AcSWEET11 could improve sugar accumulation in pineapple callus and transgenic tomato, which suggests that AcSWEET11 might positively contribute to sugar accumulation in pineapple fruit development. These results may provide insights to enhance sugar accumulation in fruit, thus improving pineapple quality in the future.

Metabolomic and transcriptomic analyses reveal the mechanism of sweet-acidic taste formation during pineapple fruit development.

Pineapple (Ananas comosus L.) is one of the most valuable subtropical fruit crop in the world. The sweet-acidic taste of the pineapple fruits is a major contributor to the characteristic of fruit quality, but its formation mechanism remains elusive. Here, targeted metabolomic and transcriptomic analyses were performed during the fruit developmental stages in two pineapple cultivars (“Comte de Paris” and “MD-2”) to gain a global view of the metabolism and transport pathways involved in sugar and organic acid accumulation. Assessment of the levels of different sugar and acid components during fruit development revealed that the predominant sugar and organic acid in mature fruits of both cultivars was sucrose and citric acid, respectively. Weighted gene coexpression network analysis of metabolic phenotypes and gene expression profiling enabled the identification of 21 genes associated with sucrose accumulation and 19 genes associated with citric acid accumulation. The coordinated interaction of the 21 genes correlated with sucrose irreversible hydrolysis, resynthesis, and transport could be responsible for sucrose accumulation in pineapple fruit. In addition, citric acid accumulation might be controlled by the coordinated interaction of the pyruvate-to-acetyl-CoA-to-citrate pathway, gamma-aminobutyric acid pathway, and tonoplast proton pumps in pineapple. These results provide deep insights into the metabolic regulation of sweetness and acidity in pineapple.

A role for MIR828 in pineapple fruit development.

Chen et al. ( Nature Genet. 51: 1549-1558; Oct. 2019) sequenced Ananas comosus var. bracteatus accession CB5, cultivated for its bright pink-to-red colored fruit, and yellow-fleshed A. comosus accession F153, reporting an improved F153 reference assembly while annotating MICRORNA (MIRNA) loci and gene family expressions relevant to lignin and anthocyanin biosynthesis. An independent article (Xiong et al.Sci. Rep. 8: 1947; 2018) reported var. bracteatus MIRNAs but not MIR828, a negative regulator of anthocyanin and polyphenolics biosynthesis by targeting MYB transcription factors associated with UV light- and sugar-signaling in dicots. MIR828 has been reported in gymnosperms, Amborella (sister to flowering plants), and basal monocot orders Liliales, Asparagales, Zingiberales, Arecales, but not in the Poales, a sister order comprising grasses and ~3,000 species of bromeliads including pineapple. Here I show MIR828 exists in pineapple and directs post-transcriptional gene silencing of mRNAs encoding MYB family members with inferred function to regulate the conspicuous red fruit trait in var. bracteatus. MIR828 plesiomorphy (an ancient basal trait) may shed light on monocot apomorphic fruit development, postulated for 21 monocot families with fleshy fruits as due to homoplasy/convergence driven by tropical climate and/or enticements to vertebrate endozoic seed dispersers.

A role for MIR828 in pineapple fruit development.

Chen et al. ( Nature Genet. 51: 1549-1558; Oct. 2019) sequenced Ananas comosus var. bracteatus accession CB5, cultivated for its bright pink-to-red colored fruit, and yellow-fleshed A. comosus accession F153, reporting an improved F153 reference assembly while annotating MICRORNA (MIRNA) loci and gene family expressions relevant to lignin and anthocyanin biosynthesis. An independent article (Xiong et al.Sci. Rep. 8: 1947; 2018) reported var. bracteatus MIRNAs but not MIR828, a negative regulator of anthocyanin and polyphenolics biosynthesis by targeting MYB transcription factors associated with UV light- and sugar-signaling in dicots. MIR828 has been reported in gymnosperms, Amborella (sister to flowering plants), and basal monocot orders Liliales, Asparagales, Zingiberales, Arecales, but not in the Poales, a sister order comprising grasses and ~3,000 species of bromeliads including pineapple. Here I show MIR828 exists in pineapple and directs post-transcriptional gene silencing of mRNAs encoding MYB family members with inferred function to regulate the conspicuous red fruit trait in var. bracteatus. MIR828 plesiomorphy (an ancient basal trait) may shed light on monocot apomorphic fruit development, postulated for 21 monocot families with fleshy fruits as due to homoplasy/convergence driven by tropical climate and/or enticements to vertebrate endozoic seed dispersers.

Global identification and expression analysis of pineapple aquaporins revealed their roles in CAM photosynthesis, boron uptake and fruit domestication

Pineapple is a crassulacean acid metabolism (CAM) plant with high economic value. Originated at semi-arid regions where water is limited, CAM plant is known for its high water use efficiency (WUE). Aquaporin regulates whole plant level water usage and transportation, which are critical for many physiological processes, including photosynthesis. Systematically identification and analyses of the aquaporin family resulted in detailed annotation of this gene family in pineapple. Among the 36 aquaporins identified in pineapple genome, 10 members were found in the TIP subfamily, 10 members were found in the PIP subfamily, 11 members were found in the NIP subfamily, and 3 members were found in the SIP subfamily. Additionally, there was also one TIP1-like aquaporin and one NIP1-like aquaporin that shared sequence similarity to TIP1 and NIP1 aquaporins respectively. Using transcriptome data from leaf tissues sampled every 2 hs in 24 h, we discovered aquaporin genes with circadian expression patterns in the domesticated pineapple and revealed the potential functions of all aquaporin genes for pineapple and CAM plants in general. To understand the domestication history of aquaporin, we compared the aquaporins from wild pineapple and cultivars, and found that the aquaporin expression profile in domesticated pineapple fruit development is very different from the wild pineapple, implicating the importance of aquaporin genes in the process of domesticated fruit development, such as rapid fruit expansion and ripening. This research has also targeted aquaporin subfamily nodulin26-like intrinsic protein5-1 (NIP5-1) gene in pineapple, which plays an important role in boron transportation, and had not yet been revealed in any monocot species. CAM plant has unique circadian regulation mechanisms for aquaporin genes in comparison with C3 plants, which might be critical for its effective plant water utilization. Our result provided new insights into evolution and functional diversification of the CAM aquaporin family, and yielded genomic resources for improving WUE and boron transportation in C3 and cereal crops.

Comprehensive tissue-specific transcriptome profiling of pineapple (Ananas comosus) and building an eFP-browser for further study.

Pineapple is one of the most economically important tropical or subtropical fruit trees. However, few studies focus on the development of its unique collective fruit. In this study, we generated a genome-wide developmental transcriptomic profile of 14 different tissues of the collective fruit of the pineapple covering each of the three major fruit developmental stages. In total, 273 tissue-specific and 1,051 constitutively expressed genes were detected. We also performed gene co-expression analysis and 18 gene modules were classified. Among these, we found three interesting gene modules; one was preferentially expressed in bracts and sepals and was likely involved in plant defense; one was highly expressed at the beginning of fruit expansion and faded afterward and was probably involved in endocytosis; Another gene module increased expression level with pineapple fruit development and was involved in terpenoid and polyketide metabolism. In addition, we built a pineapple electronic fluorescent pictograph (eFP) browser to facilitate exploration of gene expression during pineapple fruit development. With this tool, users can visualize expression data in this study in an intuitive way. Together, the transcriptome profile generated in this work and the corresponding eFP browser will facilitate further study of fruit development in pineapple.

POTENSI LAHAN PENGEMBANGAN PERTANIAN HORTIKULTURA BUAH NANAS UNTUK PENGEMBANGAN WILAYAH DI KABUPATEN SUBANG

Subang Regency has the main sector in the field of agriculture that is pineapple fruit horticulture. According to Subang Spatial Planning Regulation of 2011 - 2031 agricultural potential that has the opportunity to increase the financing capacity of regional development is pineapple fruit. The objectives of this study were to: (1) delineate the available land for pineapple fruit, (2) evaluate the suitability of the land for pineapple fruit cultivation, (3) determine the potential land location for pineapple fruit development. The methodology used in this study was an analysis of Geographic Information System and land evaluation based on limiting factor to compare the characteristics of the land with the requirements of growing plants. The results showed that of potential land for the development of pineapple fruit is spread over the south side of Subang Regency. Sub-district prioritized the recommended for development is sub-district which have the area of available land and have the widest suitability, namely Cijambe Sub-district with an area of 2,124 hectares and Jalancagak sub-district with an area of 1,135 hectares.

Genotypic and environmental effects on the level of ascorbic acid, phenolic compounds and related gene expression during pineapple fruit development and ripening

Pineapple (Ananas comosus (L.) Merr.) is a non-climacteric tropical fruit whose ripening could be accompanied by oxidative processes and the concurrent activation of enzymatic and non-enzymatic reactive oxygen species (ROS) scavenging systems. To better understand the variability of these processes among climatic environments or genotypes in pineapple, the temporal expression dynamics for genes encoding oxidative and antioxidative stress enzymes were analyzed by real-time RT-PCR during fruit development and ripening, among three cultivars: Queen Victoria, Flhoran 41 and MD-2 hybrid, and in two climatic areas. Pineapple development and ripening involved changes in the levels of transcripts encoding for polyphenol oxidase and transcripts involved in the first steps of the phenylpropanoid pathway and in the balance of ROS, especially those encoding for ascorbate peroxydase and metallothioneins, regardless of the cultivar. Our results confirm the same dynamic in gene expression from the two environmental crop areas, however climatic conditions influenced the level of the expression of the major transcripts studied that were linked to these oxidative and antioxidant metabolisms. MT3a and MT3b transcripts were not influenced by genetic factor. The genetic effect was not significant on the various transcripts linked to the first steps of the phenylpropanoid pathway and to phenol oxidation, except 4CL ones. In ripe pineapple, highly significant relationships were found between the contents in antioxidant metabolites, i.e., ascorbic acid and total phenolic compounds, and the transcript levels of genes involved in the enzymatic ROS-scavenging system and in the biosynthesis or regeneration of ROS-scavenging compounds, like phenylpropanoids, ascorbic acid, metallothioneins.

Functional and evolution characterization of SWEET sugar transporters in Ananas comosus

Sugars will eventually be exported transporters (SWEETs) are a group of recently identified sugar transporters in plants that play important roles in diverse physiological processes. However, currently, limited information about this gene family is available in pineapple (Ananas comosus). The availability of the recently released pineapple genome sequence provides the opportunity to identify SWEET genes in a Bromeliaceae family member at the genome level. In this study, 39 pineapple SWEET genes were identified in two pineapple cultivars (18 AnfSWEET and 21 AnmSWEET) and further phylogenetically classified into five clades. A phylogenetic analysis revealed distinct evolutionary paths for the SWEET genes of the two pineapple cultivars. The MD2 cultivar might have experienced a different expansion than the F153 cultivar because two additional duplications exist, which separately gave rise to clades III and IV. A gene exon/intron structure analysis showed that the pineapple SWEET genes contained highly conserved exon/intron numbers. An analysis of public RNA-seq data and expression profiling showed that SWEET genes may be involved in fruit development and ripening processes. AnmSWEET5 and AnmSWEET11 were highly expressed in the early stages of pineapple fruit development and then decreased. The study increases the understanding of the roles of SWEET genes in pineapple.

Microarray analysis of gene expression profiles in ripening pineapple fruits

BackgroundPineapple (Ananas comosus) is a tropical fruit crop of significant commercial importance. Although the physiological changes that occur during pineapple fruit development have been well characterized, little is known about the molecular events that occur during the fruit ripening process. Understanding the molecular basis of pineapple fruit ripening will aid the development of new varieties via molecular breeding or genetic modification. In this study we developed a 9277 element pineapple microarray and used it to profile gene expression changes that occur during pineapple fruit ripening.ResultsMicroarray analyses identified 271 unique cDNAs differentially expressed at least 1.5-fold between the mature green and mature yellow stages of pineapple fruit ripening. Among these 271 sequences, 184 share significant homology with genes encoding proteins of known function, 53 share homology with genes encoding proteins of unknown function and 34 share no significant homology with any database accession. Of the 237 pineapple sequences with homologs, 160 were up-regulated and 77 were down-regulated during pineapple fruit ripening. DAVID Functional Annotation Cluster (FAC) analysis of all 237 sequences with homologs revealed confident enrichment scores for redox activity, organic acid metabolism, metalloenzyme activity, glycolysis, vitamin C biosynthesis, antioxidant activity and cysteine peptidase activity, indicating the functional significance and importance of these processes and pathways during pineapple fruit development. Quantitative real-time PCR analysis validated the microarray expression results for nine out of ten genes tested.ConclusionsThis is the first report of a microarray based gene expression study undertaken in pineapple. Our bioinformatic analyses of the transcript profiles have identified a number of genes, processes and pathways with putative involvement in the pineapple fruit ripening process. This study extends our knowledge of the molecular basis of pineapple fruit ripening and non-climacteric fruit ripening in general.

IDENTIFICATION AND CHARACTERIZATION OF DIFFERENTIALLY EXPRESSED MICRORNAS DURING FRUIT RIPENING IN PINEAPPLE (ANANAS COMOSUS VAR. COMOSUS)

MicroRNAs (miRNAs) are a class of small, non-coding, endogenous RNAs that negatively regulates gene expression by cleaving or repressing the translational process of protein-coding mRNA transcripts. To determine if pineapple fruit development and ripening was mediated by miRNA, miRNA were detected and quantified at pre- and post-ripening stages using RT-qPCR. The expression profiles of 13 miRNAs namely miR156, miR157, miR159, miR162, miR164, miR165, miR167, miR168, miR169, miR170, miR171, miR172, and miR390 were detected in pineapple. Among these 13 miRNAs, only the genes (miR168, miR390, and miR164) displayed clear differential expression during pre-ripening and post-ripening stages of the fruit. During the post-ripening stage, miR168 and miR390 were up-regulated 1.79- and 2.64-fold, respectively, while expression of miR164 dropped to 0.07-fold compared to the pre-ripening stage. The discovery of miRNAs from this study together with its stage-regulated expression profiles are excellent candidates for further investigation into pineapple crop improvement through functional genomes.

English

In pineapple fruits, sugar accumulation plays an important role in flavor characteristics, which varies according to the stage of fruit development. Metabolic changes in the contents of fructose, sucrose and glucose and reducing sugar related to the activities of soluble acid invertase (AI), neutral invertase (NI), sucrose synathase (SS) and sucrose-phosphate synthase (SPS) were studied in winter and summer pineapple fruits in this paper. Sucrose was significantly increased in most of the harvesting winter fruits which reached the peak of 64.87 mg·g-1 FW at 130 days after anthesis, while hexose was mainly accumulated at the 90 day of the summer fruits in July. The ratio of hexose to sucrose was 5.92:0.73 from the winter fruit in February. Interestingly, the activities of SPS and SS synthetic direction of the harvested fruits in February were significantly higher than those in July, whereas the invertase activities were exactly opposite. NI activity showed a similar trend to AI, but the amount of NI activity was higher than AI in both months. Therefore, NI appears to be one of the vital enzymes in pineapple fruit development. Conclusively, the enzyme activities related to sugar play key roles in the eating of quality pineapple, which could be improved by cultivation in different seasons. So we can arbitrate different temperature to improve the quality of pineapple fruits according to market demand.   Key words: Pineapple (Ananas comosus), different harvest seasons, sucrose, sucrose phosphate synthase, sucrose synthase.

Cloning and expression of pineapple sucrose-phosphate synthase gene during fruit development

A 1132-base pairs (bp) polymerase-chain-reaction product of sucrose-phosphate synthase (SPS) (EC 2.3.1.14) from pineapple (Ananas comosus cv. Comte de paris) fruit was cloned and nominated as Ac-SPS1. The sequence encodes a putative 377 amino acids protein containing two serine conserved features that had been found in other plant SPS genes: the presence of a 14-3-3 protein special binding domain and an activated site of osmosis stress, which can been activated by phosphorylation and dephosphorylation. The Neighbour-joining tree revealed that Ac-SPS1 belonged to the first kind of sucrose phosphate synthase gene. The results indicated that, the Ac-SPS1 expression was low in the earlier period of fruit growth, then, increasing from 20 days after anthesis and gradually a falling on 40 days, reached the peak with the highest value around 70 days. The SPS activity and sucrose content reached their maximum 80 days after anthesis. It proved that the accumulation of sucrose was correlated with SPS activity and mRNA content and it maximally occurred at 10 d after SPS mRNA and activity had reached its maxima. These results indicated that Ac-SPS1 gene played a key role in sucrose accumulation during the pineapple fruit development and transcriptional activation with increase in Ac-SPS1 expression might be important regulatory events of sugar during pineapple fruit maturation. Key words: Pineapple fruit, sucrose phosphate synthase, gene cloning, expression.

Changes in cell number and cell size during pineapple (Ananas comosus L.) fruit development and their relationship with fruit size

In mainland China, more than 80% of pineapples (Ananas comosus L.) grown are the cultivar ‘Comte de Paris’. Fruit size is an important commercial trait in crops such as pineapple and it is generally believed that cell number and cell size play an important role during fruit size regulation; however, few cellular biological studies on pineapple fruit development have been conducted. To better understand the regulation of pineapple fruit size, the changes in cell number and cell size during fruit development were analysed. Pineapple cv. ‘Comte de Paris’ fruit were collected every 15 days from 0 to 75 days after the first flower appeared (DAFF), and the flesh of the second (top) and the sixth (base) fruitlets were selected for histological observation. Cell size exhibited a rapid increase up to 60 DAFF, while the cell rapidly proliferated up to 30 DAFF, then slowed down but continued to proliferate. Although grown under identical conditions, ‘Comte de Paris’ pineapples grew to different sizes. The results showed that the cell number, the cell size and the number of fruitlets were correlated with the final fruit size/weight regulation, but that cell number played the most important role.

Developing pineapple fruit has a small transcriptome dominated by metallothionein

In a first step toward understanding the molecular basis of pineapple fruit development, a sequencing project was initiated to survey a range of expressed sequences from green unripe and yellow ripe fruit tissue. A highly abundant metallothionein transcript was identified during library construction, and was estimated to account for up to 50% of all EST library clones. Library clones with metallothionein subtracted were sequenced, and 408 unripe green and 1140 ripe yellow edited EST clone sequences were retrieved. Clone redundancy was high, with the combined 1548 clone sequences clustering into just 634 contigs comprising 191 consensus sequences and 443 singletons. Half of the EST clone sequences clustered within 13.5% and 9.3% of contigs from green unripe and yellow ripe libraries, respectively, indicating that a small subset of genes dominate the majority of the transcriptome. Furthermore, sequence cluster analysis, northern analysis, and functional classification revealed major differences between genes expressed in the unripe green and ripe yellow fruit tissues. Abundant genes identified from the green fruit include a fruit bromelain and a bromelain inhibitor. Abundant genes identified in the yellow fruit library include a MADS box gene, and several genes normally associated with protein synthesis, including homologues of ribosomal L10 and the translation factors SUI1 and eIF5A. Both the green unripe and yellow ripe libraries contained high proportions of clones associated with oxidative stress responses and the detoxification of free radicals.

Fruit temperature and crown removal on the occurrence of pineapple fruit translucency

The roles of fruit temperature and crown removal in the occurrence of pineapple fruit translucency were determined. Pineapple fruit translucency began to appear 2–4 weeks before harvest. Flesh tissue became very susceptible to high temperature and the cell electrolyte leakage rapidly increased 4 weeks before harvest. During the early stage of fruit development, electrolyte leakage of fruit flesh was reduced by covering fruit in the field with clear-plastic or a postharvest heat treatment (48°C, 24 h). In contrast, flesh tissue electrolyte leakage was increased by the postharvest heat treatment when the fruit age was 4 weeks before harvest or older. Covering fruit with clear-plastic during the last 3 weeks of fruit development decreased titratable acidity (TA) and increased translucency severity. The effects of temperature on fruit translucency occurrence was divided into two stages: the period earlier than 6 weeks before harvest and the period from 6 weeks before harvest to harvest. This division was based upon high fruit temperature 8 weeks before harvest or earlier reduced electrolyte leakage of the fruit flesh tissue, but increased leakage when the fruit age was 4 weeks before harvest or older. Crown removal either at an early or late stage of fruit development did not have any significant effect on fruit weight or translucency occurrence. The results suggested that the crown did not play a significant role in pineapple fruit development and translucency occurrence.

ON FARM APPROACH OF PINEAPPLE FRUITLET CORE ROT DISEASE IN MARTINIQUE

Fruitlet Core Rot is one on the main disease that affects pineapple fruit development in the world. However, factors promoting the disease are not well known. A large survey, including soil, climatic, physiological and pathological variables at a field scale, and including spatial heterogeneity and temporal variability, was designed and conducted in the pineapple production area in Martinique. This on farm-approach allowed the identification and specification of the main factors responsible for the disease. Fruit sampling analysis revealed the Penicillium funiculosum was involved in 95 % of the observer cases. However, although P. funiculosum was widespread in the soils of the survey, no quantitative relation was established between the quantity of inoculum in the soil or on the plant and the development of P. funiculosum in fruits. Fruit observations at harvest time showed a high level of variation between fruits within a field. However, significant correlations between the percentage of infected fruits within a field, the average number of spots per fruit and their size were established. A global analysis of the data showed that average ascorbic acid content in fruits at harvest is negatively linked with the percentage of infected fruits. The nutritional status of the plants, especially low levels of calcium and magnesium, and/or high levels of nitrogen, is also a significant promoting factor for the development of the disease. It is concluded that Fruitlet Core Rot in Martinique is promoted by a combination of factors which determine the sensitivity of fruits. Climatic conditions before harvest, acid content, and nutritional status are the main factors. (Resume d'auteur)