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The detection and localization of pineapple fruit must be successfully conducted to realize intelligent picking. This paper proposed a method for detecting and localizing pineapples in natural environments based on binocular stereo vision and an improved YOLO (You Only Look Once) v3 model. In comparison with the original YOLOv3, the improved algorithm did the following two improvement: the DenseNet was added into the Darknet-53 backbone network to optimize the 13 × 13 and 26 × 26 feature layer, and the SPP-net was fused in the 52 × 52 dimension detection module to strengthen the information representation ability of feature map. A binocular camera acquired left and right images. The left image was then input to the improved YOLOv3 model to obtain the position information of pineapples in the image. Stereo matching and parallax calculation of the target pineapple region were completed via the stereo matching algorithm. Finally, the three-dimensional co-ordinates of pineapples were calculated based on the triangulation principle of binocular stereo vision. A series of experiments were run to compare the detection result of this method against YOLOv3, Faster-RCNN (Region Convolutional Neural Network) and Mobilenet-SSD (Single Shot MultiBox Detector) as per their respective F1 score (Balanced Score) and AP (Average Precision) values. On test set with slight occlusion, the F1 score and AP values of the improved YOLOv3 model were 93.18% and 97.55%, respectively. As the occlusion grew severe, the F1 score and AP values decreased to 89.15% and 91.47%, respectively. The improved YOLOv3 model developed in this study had the best detection effect among all models tested. The binocular stereo vision localization experiment showed an average absolute error of 24.414 mm and average relative error of 1.17% at a distance of 1.7–2.7 m. The proposed method may thus be suitable for picking robots detecting and localizing pineapple fruit in natural environments.

The genetic erosion of the Ananas Mill. genus has been accelerating in recent years. In the Pineapple Active Germplasm Bank (AGB) of the Embrapa Cassava and Fruits research unit ( Embrapa Mandioca e Fruticultura ), in vitro safety duplication has been an efficient strategy to protect this important germplasm. However, there are indications that in vitro culture conditions can cause somaclonal variations that interfere in the rescue and subsequent cultivation of the genetic material. Therefore, the objective of this work was to evaluate in field conditions the genetic stability of 45 accessions of different botanical varieties of Ananas , after in vitro conservation for 10 years, and to consolidate the efficiency of this type of conservation. Six plants of each accession were acclimatized and submitted to all the steps until transplantation to the field, where the morphological characterization was performed based on 21 quantitative and qualitative descriptors in two production cycles of pineapple plants. The accessions presented a normal production cycle, with genetic variations only noted in accessions AGB-003 and AGB-020 ( Ananas comosus var. bracteatus (Lindl.) Coppens & F. Leal]). Some accessions in this evaluation could not be grouped with their corresponding plants grown in the AGB field, mainly regarding quantitative data. This was due to the greater vigor of these plants because they came from in vitro culture and were virus free. The results demonstrated the morphological stability of the preserved accessions even after the long in vitro conservation period, permitting the validation of this technique as a secure and efficient strategy to preserve pineapple germplasm.

Background Ananas comosus var. bracteatus is a colorful plant used as a cut flower or landscape ornamental. The unique foliage color of this plant includes both green and red leaves and, as a trait of interest, deserves investigation. In order to explore the pigments behind the red section of the chimeric leaves, the green and red parts of chimeric leaves of Ananas comosus var. bracteatus were sampled and analyzed at phenotypic, cellular and molecular levels in this study. Results The CIELAB results indicated that the a* values and L* values samples had significant differences between two parts. Freehand sections showed that anthocyanin presented limited accumulation in the green leaf tissues but obviously accumulation in the epidermal cells of red tissues. Transcriptomic and metabolomic analyses were performed by RNA-seq and LC-ESI-MS/MS. Among the 508 identified metabolites, 10 kinds of anthocyanins were detected, with 6 significantly different between the two samples. The cyanidin-3,5-O-diglucoside content that accounts for nearly 95.6% in red samples was significantly higher than green samples. RNA-Seq analyses showed that 11 out of 40 anthocyanin-related genes were differentially expressed between the green and red samples. Transcriptome and metabolome correlations were determined by nine quadrant analyses, and 9 anthocyanin-related genes, including MYB5 and MYB82 , were correlated with 7 anthocyanin-related metabolites in the third quadrant in which genes and metabolites showing consistent change. Particularly, the PCCs between these two MYB genes and cyanidin-3,5-O-diglucoside were above 0.95. Conclusion Phenotypic colors are closely related to the tissue structures of different leaf parts of Ananas comosus var. bracteatus , and two MYB transcription factors might contribute to differences of anthocyanin accumulation in two parts of Ananas comosus var. bracteatus chimeric leaves. This study lay a foundation for further researches on functions of MYBs in Ananas comosus var. bracteatus and provides new insights to anthocyanin accumulation in different parts of chimeric leaves.

The Turiaçu pineapple cultivar produces fruits of high organoleptic value but has few biotechnological studies on seedling production. However, conventional in vitro propagation can affect the photosynthetic potential of plants when transferred to the field, thus mitigating measures should be undertaken to solve this limitation, for example by decreasing carbohydrate concentration in the growth medium, adopting bioreactors of temporary immersion with forced ventilation, and using gas permeable membranes in the culture flask. The present work focused on evaluating the growth and development of plantlets from Ananas comosus [L]. Merr. cultivar Turiaçu, an important but neglected pineapple cultivar, under different sucrose concentrations and cultivation systems. For that, the impact of the photomixotrophic and photoautotrophic growth on morphophysiological responses of plants and survival during the ex vitro acclimatization was assessed. The plants were grown in four cultivation systems: permanent immersion system with sealed flasks (PIS-SF); permanent immersion system with natural ventilation (PIS-NV); single-flask temporary immersion bioreactors (TIS-PF); and twin-flasks temporary immersion bioreactors (TIS-RALM), combined with sucrose concentrations (0, 5.0, 15.0, and 30.0 g L −1 ). The results indicate that Turiaçu plants have photoautotrophic potential in vitro , as the photochemical efficiency of the plants increased in cultivation systems with TIS –RALM gas exchange without the addition of sucrose. Furthermore, it also improved the performance and hardening of plants in ex vitro conditions, which constitutes a crucial step towards the diffusion of this cultivar.

Background Lysine succinylation, an important protein posttranslational modification (PTM), is widespread and conservative. The regulatory functions of succinylation in leaf color has been reported. The chimeric leaves of Ananas comosus var. bracteatus are composed of normal green parts and albino white parts. However, the extent and function of lysine succinylation in chimeric leaves of Ananas comosus var. bracteatus has yet to be investigated. Results Compared to the green (Gr) parts, the global succinylation level was increased in the white (Wh) parts of chimeric leaves according to the Western blot and immunohistochemistry analysis. Furthermore, we quantitated the change in the succinylation profiles between the Wh and Gr parts of chimeric leaves using label-free LFQ intensity. In total, 855 succinylated sites in 335 proteins were identified, and 593 succinylated sites in 237 proteins were quantified. Compared to the Gr parts, 232 (61.1%) sites in 128 proteins were quantified as upregulated targets, and 148 (38.9%) sites in 70 proteins were quantified as downregulated targets in the Wh parts of chimeric leaves using a 1.5-fold threshold ( P  < 0.05). These proteins with altered succinylation level were mainly involved in crassulacean acid metabolism (CAM) photosynthesis, photorespiration, glycolysis, the citric acid cycle (CAC) and pyruvate metabolism. Conclusions Our results suggested that the changed succinylation level in proteins might function in the main energy metabolism pathways—photosynthesis and respiration. Succinylation might provide a significant effect in the growth of chimeric leaves and the relationship between the Wh and Gr parts of chimeric leaves. This study not only provided a basis for further characterization on the function of succinylated proteins in chimeric leaves of Ananas comosus var. bracteatus but also provided a new insight into molecular breeding for leaf color chimera.

The use of nanoparticles in the appropriate portion to increase plant growth and development is an ongoing biological process. However, its exposure in an inconsiderable proportion become stressful and plant uses diverse regulatory mechanisms such as gene expression and miRNAs regulation to attain their cellular homeostasis. This study documented the influence of MgO NPs on genes and miRNAs expression, cell morphology, chlorophyll content, and physiological changes in Ananas comosus var. bracteatus at different treatment levels. It's found that as MgO NPs exposed to the plant's increased, the average root length, average biomass, and average leaf length significantly decreased. A low concentration of MgO NPs (1 g/mL) increased the chlorophyll content of leaves, while 2 and 4 g/mL decreased it significantly. A 4 g/mL of MgO NPs increased the expression of miR-396 and miR-398 extremely, while repressed the expression of RHS12 and XTH genes significantly. Furthermore, the number of vascular bundles of root stele decreased obviously under 4 g/mL MgO NPs. 20 nm MgO NPs may have a destructive influence on the growth and development of Ananas comosus var. bracteatus by inhibiting chlorophyll.

The genus Fusarium is largely known due to its economical relevance, affecting several agronomically important crops. The pineapple fusariosis, caused by F . guttiforme , is among the most important diseases in pineapple ( Ananas comosus var. comosus (L.) Merrill Cppens & Leal) worldwide, causing seedling and fruit losses estimated in 20% and 40%, respectively. Because this pathogen can potentially induce 100% production losses, studies seeking efficient and long-lasting disease management strategies are required. This study aimed to assess the Fusarium species diversity associated with pineapple fusariosis in the North region of the state of Rio de Janeiro, Brazil. Symptomatic pineapple fruit were collected from different producing areas, and 20 Fusarium isolates were obtained through indirect isolation. The proper fungal species identification was carried out based on nucleotide sequences of the translation elongation factor 1α ( tef1 ) and β-tubulin ( tub2 ) genomic regions. Also, the aggressiveness of Fusarium isolates was evaluated through inoculation of fruit and leaves of the susceptible pineapple cultivar Pérola. The Bayesian phylogenetic analysis reinforced that Fusarium guttiforme was the only species identified infecting pineapple in the North of Rio de Janeiro, with the new isolates forming a monophyletic group with a previously reported F. guttiforme isolate. Although the close genetic relationship observed among tef-1α and β-tub2, at 99.1-100.0% nucleotide identity, differences in aggressiveness were observed. All isolates of F. guttiforme caused lesions on leaves and fruits; however, nine isolates stood out as more aggressive towards fruit, and two as more aggressive on the leaves. The F. guttiforme isolates identified here can be used as inoculum sources to evaluate putative genetic resistance in pineapple breeding programs.

Ananas comosus var. bracteatus is an important ornamental plant because of its green/white chimeric leaves. The accumulation of anthocyanin makes the leaf turn to red especially in the marginal part. However, the red fades away in summer and winter. Light intensity is one of the most important factors affecting leaf color along the seasons. In order to understand the effects of light intensity on the growth and coloration of the chimeric leaves, Ananas comosus var. bracteatus was grown under full sunlight, 50% shade and 75% shade for 75 days to evaluate the concentration of pigments, the color parameters (values L*, a*, b*) and the morpho-anatomical variations of chimeric leaves. The results showed that a high irradiance was beneficial to keep the chimeric leaves red. However, prolonged exposure to high irradiance caused a damage, some of the leaves wrinkled and even burned. Shading instead decreased the concentration of anthocyanin and increased the concentration of chlorophyll, especially in the white marginal part of the leaves. Numerous chloroplasts were observed in the mesophyll cells of the white marginal part of the chimeric leaves under shading for 75 days. The increase in chlorophyll concentration resulted in a better growth of plants. In order to balance the growth and coloration of the leaves, approximately 50% shade is suggested to be the optimum light irradiance condition for Ananas comosus var. bracteatus in summer.

The Pineapple mealybug wilt-associated virus (PMWaV) provokes a disease that causes considerable losses to pineapple growers due to the reduced leaf tissue turgescence, resulting in leaf necrosis and death in severe cases. In this work, we describe the comparison of shoot tip culture and cryotherapy methods to eradicate the pineapple wilt disease-associated ampeloviruses. Plants from the accessions Ananas comosus var. comosus (AGB-009), var. bracteatus (AGB-119), and var.parguazensis (AGB-376) were indexed by RT-PCR, confirming mixed infections of PMWaV-1, PMWaV-2, and PMWaV-3. The accessions were cultured in vitro and their shoot tips treated by cryotherapy following a droplet vitrification protocol. The regeneration rate from shoot tip culture was 93% for AGB-376 and 100% for the other two accessions. After freezing, AGB-376 had 100% regeneration subsequent to exposure to PVS2 for 45 min, followed by 95% for AGB-009, while for AGB-119 the optimal exposure time was 60 min, with plant regeneration from nearly 80% of the shoot tips. For the accessions AGB-009 and AGB-376, all the recovered plants were virus free by the two methods, while 50% of the plants from accession AGB-119 remained infected. These results indicate that shoot tip culture alone or in association with cryotherapy is a promising routine method for virus removal from pineapple plant tissues and is useful to ensure that backup reserves of pineapple germplasm, conserved by in vitro bank and cryobank, are formed with virus-free plants.

The aim of this work was to evaluate the activity of bromelain in pineapple plants ( Ananas comosus var. Comosus ), Pérola cultivar, produced in vitro in different culture conditions. This enzyme, besides its pharmacological effects, is also employed in food industries, such as breweries and meat processing. In this work, the enzymatic activity was evaluated in the tissues of leaves and stems of plants grown in culture medium without plant growth regulator. The most significant levels of bromelain were observed in leaf tissue after 4 months of culture in vitro in medium with a filter paper bridge, followed by medium gelled by the agar. The results of this study, regarding the different structures of the pineapple (leaves and stems) in vitro showed that the activity of bromelain varied depending on the culture conditions, the time and structure of which was quantified, ensuring a viable strategy in the production of seedlings with high levels of bromelain in subsequent phases of micropropagation.