Bulb Organs Research Articles

Genome-wide association analysis identifies candidates of three bulb traits in garlic.

Garlic bulbs generally possess several swelling cloves, and the swelling degree of the bulbs determines its yield and appearance quality. However, the genetic basis underlying bulb traits remains poorly known. To address this issue, we performed a genome-wide association analysis for three bulb traits: bulb weight, diameter, and height. It resulted in the identification of 51 significant associated signals from 38 genomic regions. Twelve genes from the associated regions, whose transcript abundances in the developmental bulb showed significant correlations with the investigated traits in 81 garlic accessions, were considered the candidates of the corresponding locus. We focused on five of these candidates and their variations and revealed that the promoter variations of fructose-bisphosphate aldolase-encoding Asa8G05696.1 and beta-fructofuranosidase-encoding Asa6G01167.1 are responsible for the functional diversity of these two genes in garlic population. Interestingly, our results revealed that all candidates we focused on experienced a degree of selection during garlic evolutionary history, and different genotypes of them were retained in two China-cultivated garlic groups. Taken together, these results suggest a potential involvement of those candidates in the parallel evolution of garlic bulb organs in two China-cultivated garlic groups. This study provides important insights into the genetic basis of garlic bulb traits and their evolution.

A new tarantula (Mygalomorphae: Theraphosidae) genus endemic from Peru with a novel genitalic morphology among theraphosinae and its phylogenetic placement

Chinchaysuyu gen. nov. is described as a new monotypic Theraphosidae genus from northern Peru, with distinct genitalic morphology. Males of Chinchaysuyu gen. nov. differ from all known species by having a palpal bulb organ with many conspicuous keels extending towards the subtegulum. Females differ by having two pairs of short and hyper-sclerotized receptacles. This new genus is described and illustrated on the basis of the type species Chinchaysuyu spinosa sp. nov. and their morphological affinities and its phylogenetic position are analyzed and discussed.

Transcriptome profiling revealed salt stress-responsive genes in Lilium pumilum bulbs.

Lilium pumilum is an important ornamental, culinary and medicinal bulbous plants with salt tolerance. However, salt tolerance of lily, particularly the bulb, has been studied relatively little, which brings challenges to the cultivation of lily varieties with high salt tolerance. Here, we performed transcriptome sequencing on the bulb organs of L. pumilum under salt stress treatment, analyzed differential gene expressed levels and then identified several key genes associated with salt stress tolerance at genome-wide scale. For the first time, we revealed the obvious response against salt stress for L. pumilum bulb organs, while distinct from those for root organs. Several key genes obtained through transcriptome analysis and DEG screening include NF-YB3 transcription factor, metallothionein type 2 protein, vicilin like seed storage protein and bidirectional sugar transporter SWEET14. Rather than typical ROS scavengers like superoxide dismutase, peroxidase, and glutathione transferase, non-typical ROS scavengers such as the metallothionein type 2 protein, and vicilin like seed storage protein were upregulated in our work. The bidirectional sugar transporter SWEET14 protein and the hormone signaling proteins such as E3-ubiquitin protein ligases, PYL4 and protein phosphatase 2C were also upregulated, suggesting the role of sugars and hormones in the bulb organ responses to salt stress. Co-expression analysis of the DEGs further confirmed that NF-YB3 transcription factor acted as a hub gene, suggesting that salt stress can promote flowering of L. pumilum. Taken together, we identified important candidate genes associated with salt tolerance of the L. pumilum bulb organs, which may provide the excellent basis for further in-depth salt tolerance mechanisms of the lily bulbs.

Phenology‐regulated defence mechanisms as drivers for Fusarium basal rot in onion (Allium cepa)

AbstractFusarium basal rot (FBR), caused by Fusarium spp., is a serious impediment for onion production. In the present study, the interaction of onion (Allium cepa) var. Takstar F1 with Allium‐derived isolates of the toxigenic species F. oxysporum and F. proliferatum was investigated at seedling and bulb stage. Using a set of isolates with distinct virulence profiles, we provide evidence that the outcome of FBR is driven by the phenology of onion. Reverse transcription‐quantitative PCR analysis revealed distinct expression of reliable marker genes for phenylalanine ammonia‐lyase (PAL1, PAL2), lipoxygenase (LOX2), chalcone synthase (CHS), anthocyanidin synthase (ANS) and pectin methylesterases (PME) during the infection of seedlings and bulbs. These defence‐related genes in seedlings were differentially expressed depending on the aggressiveness of Fusarium isolates. Despite these differential kinetics, the activated plant defence did not seem to be effective in protecting the seedlings from Fusarium infection and proliferation. Meanwhile, gene expression in the bulb organs correlated positively with FBR severity, indicating an ineffective defence response. Among the major metabolites of these Fusarium species, beauvericin was not toxic to either the seedlings or the bulbs, while fumonisin B1 appeared to be a virulence factor specific for the seedling stage. This points to differential roles of fumonisin B1 during an infection of F. proliferatum depending on the infected organ and the phenological stage of the onion host. We hypothesize that this variation, along with the differences within and between Fusarium species in terms of virulence and metabolism, contributes to the determination of disease outcome.

Kankuamo, a new theraphosid genus from Colombia (Araneae, Mygalomorphae), with a new type of urticating setae and divergent male genitalia.

A new monotypic Theraphosidae genus, Kankuamo Perafán, Galvis & Pérez-Miles, gen. n., is described from Colombia, with a new type of urticating setae. These setae differ from others principally by having a small distal oval patch of lanceolate reversed barbs. Males of Kankuamo gen. n. additionally differ by having a palpal bulb organ very divergent from all known species, with many conspicuous keels dispersed across the median tegulum to the tip, mostly with serrated edges. Females differ by having spermathecae with a single notched receptacle, with two granulated lobes and several irregular sclerotized longitudinal striations. The new urticating setae, type VII, is characterized, illustrated and its releasing mechanism is discussed. It is hypothesized that these setae are the first in Theraphosinae subfamily whose release mechanism is by direct contact. Kankuamo gen. n. is described and illustrated on the basis of the type species Kankuamo marquezi Perafán, Galvis & Gutiérrez, sp. n., and their remarkable characteristics, morphological affinities and cladistic relationship are analyzed.

Developmental changes and water status in tulip bulbs during storage: visualization by NMR imaging.

Magnetic Resonance Imaging (MRI) and light and scanning electron microscopy (SEM) were used to follow time-dependent morphological changes and changes in water status of tulip bulbs (Tulipa gesneriana L., cv. 'Apeldoorn') during bulb storage for 12 weeks at 20 degrees C (non-chilled) or 4 degrees C (chilled) and after planting. MR images reflecting the water content, the relaxation times T1 and T2 (or their reciprocal values, the relaxation rates R1 and R2), and the apparent self-diffusion coefficient of water molecules (ADC), were obtained for intact bulbs. After planting, scape elongation and flowering occurred only in chilled bulbs, while elongation in non-chilled bulbs was retarded. Microscopic observations showed different structural components and high heterogeneity of the bulb tissues. MRI revealed the elongation of the flower bud during storage, which was significantly faster in the chilled bulbs. In addition, MRI demonstrated a redistribution of water between different bulb organs, as well as significant differences in the pattern of this redistribution between the chilled and non-chilled bulbs. Generally, R2 relaxation rates became faster in all bulb organs during storage. At the same time, ADC values remained constant in the chilled bulbs, while exhibiting a significant increase in the non-chilled bulbs.

Developmental changes and water status in tulip bulbs during storage: visualization by NMR imaging

Magnetic Resonance Imaging (MRI) and light and scanning electron microscopy (SEM) were used to follow time‐dependent morphological changes and changes in water status of tulip bulbs (Tulipa gesneriana L., cv. ‘Apeldoorn’) during bulb storage for 12 weeks at 20 °C (non‐chilled) or 4 °C (chilled) and after planting. MR images reflecting the water content, the relaxation times T1 and T2 (or their reciprocal values, the relaxation rates R1 and R2), and the apparent self‐diffusion coefficient of water molecules (ADC), were obtained for intact bulbs. After planting, scape elongation and flowering occurred only in chilled bulbs, while elongation in non‐chilled bulbs was retarded. Microscopic observations showed different structural components and high heterogeneity of the bulb tissues. MRI revealed the elongation of the flower bud during storage, which was significantly faster in the chilled bulbs. In addition, MRI demonstrated a redistribution of water between different bulb organs, as well as significant differences in the pattern of this redistribution between the chilled and non‐chilled bulbs. Generally, R2 relaxation rates became faster in all bulb organs during storage. At the same time, ADC values remained constant in the chilled bulbs, while exhibiting a significant increase in the non‐chilled bulbs.

Importance of dormancy and sink strength in sprouting of onions (Allium cepa) during storage

In onion (Allium cepa L.) postponement of sprouting is necessary to achieve long term storage. We studied the factors determining sprouting during dry storage at 16°C. The period to visible sprouting depends on the length of the dormancy period, if present, and on the growth rate of the sprout. In the three cultivars tested, sprouts were initiated within 2 weeks after harvest indicating the absence of a real dormancy period. Sprout length increased linearly during storage. The mitotic activity of the apex decreased before harvest, was low at the transition from scale to leaf formation, and increased again when the sprout was initiated. From a few weeks before harvest, the initially high fructan content of the scales decreased, leading to a large increase in fructose. The sprout always contained enough carbohydrates for growth (between 50 and 60 mg g−1 dry weight, of which 30% was fructan). The activity of sucrose synthase (EC 2.4.1.13) increased as the sprout grew, indicating an increase in sink strength. Invertase (EC 3.2.1.26) was absent in all bulb organs, during the various developmental stages. Although carbohydrates and enzymes were available for fast sprouting, sprout growth was still linear instead of exponential during dry storage at temperatures favorable for growth (16°C). The relative importance of factors determining sprouting are discussed.

Comparative Growth and Development of Nerine bowdenii W. Watson: Bulbs in Situ versus Replanted

Flowering-size Nerine bowdenii bulbs were sampled from a commercial planting at 2-week intervals from 13 Aug. 1991 to 14 June 1992. They were dissected, and the following variables were recorded: 1) number and dry weight of fully sheathing leaf bases or leaves of each growth unit, 2) length and dry weight of foliage leaves, 3) fresh weight of outermost inflorescence, and 4) dry weight of daughter bulbs. Bulb organs that served as sinks and sources changed as the bulb progressed in its growth and developmental cycle. Before the new foliage provided photosynthates, growth depended on reserves deposited and stored in leaf bases during the preceding seasons. Reserves were used for the development of new leaves (foliage and bases), roots, and daughter bulb enlargement. Once the foliage became the photosynthate source, reserves were stored in old and new leaf bases. The inflorescence became the major sink when elongation of the scape initiated. Thereafter, daughter bulbs became the dominant sinks, receiving photosynthates from the senescence foliage and the reserves stored in leaf bases. The decrease in dry weight of the leaf bases was prominent in bulbs that remained in situ.

Des (1-3) IGF-I Potently Enhances Differentiated Cell Growth in Olfactory Bulb Organ Culture

We recently provided evidence that newborn rat olfactory bulb (OB) could be maintained in serum-free organ culture with combinations of insulin-like growth factor-I (IGF-I) and basic fibroblast growth factor (bFGF), both of which are locally synthesized. Des (1-3), or truncated, IGF-I is a potent analog of IGF-I isolated from rat and human brain. We proposed in this study to examine the effects of des (1-3) IGF-I on cell function, morphology and on neuronal and glial cell differentiation in our cultured OB model, using cell-specific immunostains for neurons (150 kDa neurofilament) and glial cells (glial fibrillary associated protein--GFAP). OB were cultured in Iscove's serum-free medium containing IGF-I or des (1-3) IGF-I both alone or in combination with bFGF. Dose dependent responses of 14C amino acid uptake showed des (1-3) IGF-I to be 3-5 fold more potent than IGF-I with a half maximal response at about 20 ng/ml in comparison to 100 ng/ml of IGF-I. The maximum response to IGF-I +/- bFGF was seen at 150 ng/ml; a ten-fold higher dose of insulin +/- bFGF was required to achieve the same response. While morphology was close to fresh 6 day OB following culture with IGF-I (150 ng/ml) and bFGF (25 ng/ml), the substitution of des (1-3) IGF-I at 50 ng/ml markedly improved morphology. Neurons were identified following culture in IGF-I or bFGF alone, but showed greater organisation in the mitral layer following combined IGF-I/bFGF culture. However, in contrast to IGF-I (150 ng/ml), des (1-3) IGF-I (50 ng/ml) supported marked neuronal expression. Furthermore, when des (1-3) IGF-I (50 ng/ml) was substituted for IGF-I, in combination with bFGF, the pattern of enhanced neuronal expression in the mitral layer was very close to that seen in the fresh 6 day bulb, with dendrites projecting to the glomerular layer. In OBs treated with no growth factors, or either IGF-I, des (1-3) IGF-I or bFGF alone, glial expression was widespread and poorly organised, suggesting an injury response. In contrast, following treatment with combinations of bFGF with IGF-I or des (1-3) IGF-I, a more ordered, though enhanced glial response was seen in glomerular and granule cell layers.(ABSTRACT TRUNCATED AT 400 WORDS)

Olfactory bulb organ culture is supported by combined insulin-like growth factor-I and basic fibroblast growth factor

A rat olfactory bulb serum-free organ culture system has been developed, using either E19 or day 1 post-natal bulbs. Whereas E19 bulbs were self-sufficient, combined insulin-like growth factor-I (IGF-I) (100 ng/ml) and basic fibroblast growth factor (FGF) (50 ng/ml) supported growth and differentiation of day 1PN bulbs over 6 days. Morphological evidence for viability and differentiation in culture were seen, similar to that occuring in vivo, including development of glomerular layer and maintenance of mitral and tufted and granule cells. Quantitative data derived using radio-labelled amino acid or glucose incorporation supported additive or synergistic effects of IGF-I and FGF. This olfactory bulb organ culture system offers the potential for further studies of brain growth, differentiation and function in vitro.

The annual cycle of Sternbergia clusiana of the Negev Desert

Annual changes in morphology of the hysteranthous desert plant Sternbergia clusiana were studied, showing (1) the timing of flower, fruit, leaf and root development, (2) the control of leaf and root growth by internal factors (fruit development) and by temperature and moisture, and (3) the course of replacement of the perennial bulb organs.

Bulb Organ Changes and Influence of Temperature on Gaseous Levels in a Modified Atmosphere Package of Precooled Tulip Bulbs

Abstract Modified atmosphere (MA) packages of tulip bulbs (Tulipa gesneriana L. ‘Kees Nelis’) composed of 5 bulbs sealed in low-density polyethylene film (LDF-301, Dow Chemical) were exposed to 20°C for one week followed by 3 weeks of temperature regimes between 15° and 25°. The temperature changes resulted in little change in package CO2 and O2 equilibrium levels. Bulbs held in air flowered poorly after 3 or 4 weeks at most of the temperature regimes. Packaged bulbs held below 25°C yielded 80–100% normal flowers after 3 or 4 weeks storage. The dry weight (DW) of daughter bulbs within bulbs in air increased 7-fold during 4 weeks storage. These bulbs also lost 25% of total bulb DW, 35% of scale DW, and 20% of floral shoot DW. There was little daughter bulb enlargement and few significant changes in DW of other bulb organs in film-packaged bulbs during storage.

Temperature Regulation of Growth and Endogenous Abscisic Acid-like Content of Tulipa gesneriana L

The ontogenetic changes of dry matter and abscisic acid (ABA)-like content in the component organs of Tulipa gesneriana L. ;Paul Richter' and ;Golden Melody' under two temperature storage regimes were determined. The organ dry matter and ABA showed marked differences during 13 and 5 C dry storage and during subsequent growth at 13 C. Scale dry matter of both cultivars declined sharply when grown at 13 C. The basalplate of the cultivars showed an initial gain in dry matter, but declined subsequently. The shoot of both cultivars stored at 13 C exhibited greater dry matter gain than at 5 C. In contrast, the bulblets of the cultivars at 5 C showed a much higher rate of dry matter accumulation than at 13 C.An inhibitory substance extracted from tulip bulb organs co-chromatographed with authentic ABA and had identical thin layer chromatographic R(F) values of ABA in five solvent systems. The total ABA content per bulb increased 3-fold in ;Golden Melody' and 2- to 4-fold in ;Paul Richter' during the course of the temperature treatments. ABA was low in the scales and shoot, but it was high in the basalplate, bulblets, and roots. It is suggested that the probable ABA biosynthetic sites of tulip bulb are the developing bulblets, basalplate, and roots.

Sensilla on the palps of selected blackflies (Diptera: Simuliidae).

Types and numbers of palpal sensilla have been determined for ♀ Simulium venustum Say and S. euryadminiculum Davies and both sexes of S. rugglesi Nicholson & Mickel and S. baffinense Twinn. Of particular interest are thin-walled, bulb-shaped organs, presumed CO2 and/or olfactory receptors, located in the sensory pit of palpal segment 3 in all species examined. Omithophilic ♀♀ have more bulb organs than the ♀♀ of the 1 manlmalophilie species examined and both types of blood-feeders have more than ♀ S. baffinense which does not take blood. Males have fewer bulb organs than ♀♀ of the same species.

Possible identification of gibberellins in tulipa gesneriana by gas-liquid chromatography

Gas-liquid chromatography of trimethylsilyl ethers of methyl esters (TMS) of partially purified extracts of tulip bulb organs on 3% OV-1 column suggested the presence of gibberellins A 1, A 5, A 8, A 9 and A 13. Gibberellins A 1, A 5, A 8 and A 9 in the fleshy scales, gibberellin A 1 in the shoot, and gibberellins A 5, A 9 and A 13 in the roots. Many of the TMS derivatives did not, however, correspond with any of the gibberellin samples available. The TMS derivatives were found to be biologically active in the dwarf pea bioassay.

Studies on the sense organs on the palps of selected culicine mosquitoes.

Four structures are found on the maxillary palps of female culicine mosquitoes: microtrichia, scales, sensilla chaetica, and thin-walled, bulb-shaped organs. The bulb organs are localized on the distal half of the ventral part of palpal segment 4, have perforated walls, are carbon dioxide receptors (Kellogg, in press), and vary in number among the species from 29/palp on Aedes aegypti to 89/palp on Culex restuans. An explanation for observed behavioral responses to carbon dioxide is given.