Soil Temperature Regulates Fruit Color Change in ‘Algerie’ Loquat: Nutritional and Hormonal Control

In Rosaceae fruit tree species, fruit and roots grow opposite because of carbohydrate competition, and root activity is thus reduced by fruit growth. In agreement with this, for some of these species soil temperature has been suggested as a factor regulating fruit ripening, but the mechanism with which it works remains unknown. In this study, we reduced loquat root activity by lowering soil temperature, expecting faster fruit growth and advanced fruit ripening. Eight 4-year-old ‘Algerie’ loquat trees, budded onto seedling rootstock, and grown outdoors in 39-l plastic containers filled with sandy-loamy soil were used. The roots of four trees were cooled by placing the containers in a cooling compartment (9.5 °C), whereas those of the other four trees were maintained at air temperature (16.5 °C). We measured lateral root primordia emergence, fruit diameter and fruit color development, carbohydrates and nitrogen partitioning, as well as GA, CK, IAA, ABA, and JA content. Lowering soil temperature increased carbohydrate translocation to the fruit and reduced root N uptake and translocation to both the canopy and the fruit. Changes in plant hormones were also caused by reduced soil temperature, and fruit color advanced. Loquat fruit ripened 8–10 days earlier when soil temperature was reduced to 9.5 °C.     

Plant growth promoting activity of seaweed liquid extracts produced from Macrocystis pyrifera under different pH and temperature conditions

Most commercial algal extracts are produced from brown algae by alkaline hydrolysis; however, little scientific information has been published regarding the details of the production process. In this research, we have investigated the effect of pH (pH 8–12) and temperature (40, 60, and 80 °C) on liquid extract production from the brown alga Macrocystis pyrifera. Production conditions influenced the physicochemical characteristics of the final product as the extract viscosity increased with increasing pH and temperature to a maximum which occurred at pH 10 and 80 °C. This suggests that at higher pH conditions, alginate and other polysaccharides were extracted. All the extracts obtained promoted growth of tomato plants (Solanum lycopersicum) and adventitious root formation in the mung bean cutting bioassay (Vigna radiata), as the pH process was increased during the production of the liquid extracts. The highest auxin-type activity was obtained with the extract produced at pH 11 and 80 °C, while the fastest tomato seedling growth was achieved with the extract produced at pH 12 and 80 °C.     

Gibberellin and growth inhibitor changes in potato tuber buds in response to cold treatment

Eye plugs removed from tubers of four potato cultivars previously stored for 14 days at 2 °C and then left at 15 °C for a further 14 days contained more gibberellin and less growth inhibitor activity than those kept at 15 °C for 28 days. Two gibberellin-active peaks were obtained when the extracts from cold-treated tubers were separated on paper chromatograms with an isopropanol/ammonia/water solvent. The main inhibitor did not appear to be abscisic acid.     

<Emphasis Type="Italic">PpVIN2</Emphasis>, an acid invertase gene family member,is sensitive to chilling temperature and affects sucrose metabolism in postharvest peach fruit

We previously reported that expression and activity of acid invertases (AI) are increased in peach fruit under chilling stress. In order to determine which AI genes respond to chilling stress, seven AI genes, two vacuolar invertases (VINs) and five cell wall-bound invertases (CWINs), were identified and cloned. The predicted amino acid sequences of the genes contain conserved sites characteristic of plant AIs such as NDPNG/A, the sucrose-binding site, and MWECV/P, a cysteine catalytic motif. Using gene-specific primers, the expression of each gene was measured in ‘Baifeng’ and ‘Yulu’ peach fruits stored at 0, 5, 10 and 20 °C. Of the seven genes, expression of PpVIN2 was the most affected by chilling stress; the largest increases were in fruit stored at 5 °C, up to 17-fold in ‘Baifeng’ fruit, and up to 280-fold in ‘Yulu’ fruit. Overall, VIN activity was much higher than CWIN activity in stored peach fruit. In both cultivars reducing sugar content increased significantly and sucrose content decreased gradually during storage at 5 °C relative to other temperatures, and was accompanied by severe chilling injury symptoms. Thus, PpVIN2 appears to be induced by chilling and may play an important role in sucrose metabolism in peach fruit subjected to cold storage.     

Expression of ethylene biosynthetic and signaling genes in relation to ripening of banana fruit after cold storage

Banana fruit are highly sensitive to chilling injury (CI), while the effect of different degrees of CI on the subsequent fruit ripening is largely unknown. In the present work, ripening characteristic of banana fruit after storage at 7 °C for 3 days or for 8 days, and expression levels of eight genes associated with ethylene biosynthetic and signaling, including MaACS1, MaACO1, MaERS1, MaERS3, and MaEIL1–4, were investigated. The results showed that banana fruit stored at 7 °C for 8 days exhibited more severe chilling symptoms than those at 7 °C for 3 days. Compared with banana fruit stored at 7 °C for 8 days, which showed abnormal ripening, more decrease in fruit firmness, while higher increase in ethylene production and hue angle were observed in banana fruit stored at 7 °C for 3 days, which could ripening normally. Moreover, gene expression profiles during ripening revealed that ethylene biosynthetic and signaling genes were differentially expressed in peel and pulp of banana fruit after storage at 7 °C for 3 days and 7 °C for 8 days. In the peel of fruit storage at 7 °C for 3 days, expression levels of MaACS1, MaACO1, MaEIL1, and MaEIL2 increased remarkably while MaERS3, MaEIL1, and MaEIL4 were enhanced in the fruit after storage at 7 °C for 8 days. In the pulp, with the exception of MaACO1 and MaERS3, expression levels of other genes did not exhibit a significant difference, between the banana fruit storage at 7 °C for 3 days and 7 °C for 8 days. Taken together, our results suggest that differential expression of ethylene biosynthetic and signaling genes such as MaERS3, MaACO1, and MaEIL2, may be related to ripening behavior of banana fruit with different degrees of CI after cold storage.     

Possible Mechanism of the Detached Unripe Green Tomato Fruit Turning Red

In general, a mature green tomato will ripen and turn red on the vine or off the vine. Interestingly, an unripe green (UG) tomato also will turn red after being detached from the plant, but the mechanism behind this is unclear. Our study showed that detached UG fruits were able to become red-ripened at the room temperature (25?°C), although fruit quality was lower than that of the vine-ripened fruit. In addition, detached UG fruits exposed to light accumulated more lycopene and total soluble sugars than those incubated in darkness. When the detached UG fruits were stored at a low temperature (10?°C), the fruit-ripening process was nearly blocked, which displayed a non-ripening phenotype. At a high temperature (35?°C), the detached UG fruit showed a yellow-color on ripening, and fruit qualities such as lycopene and soluble sugars were obviously lower than those stored at 25?°C. Moreover, detaching the UG fruit from the plant evoked a rapid increase in total respiration as well as alternative pathway respiration, but ethylene production was not stimulated during the first 24 h of storage. Importantly, the application of nPG, an inhibitor of alternative pathway respiration, markedly suppressed the wound-induced rise in total respiration and delayed the ripening of detached UG fruit. These findings imply that wound-induced respiration might be a signature for launching the onset of the ripening of detached UG fruit, and the optimal conditions of light and temperature are beneficial for the color change and the ripening processes.     

Thermal responses in the citrus fruit fly,Dacus tsuneonis: evidence for a pupal diapause

Thermal responses controlling pupariation and adult eclosion in a citrus fruit fly,Dacus tsuneonis (Miyake), were studied to understand the winter biology of this species. When mature larvae were exposed to various temperature conditions, the highest percentage of pupariation was obtained at 15 °C, although the variance at this temperature was greater than at 20 °C or 25 °C. Pupariation occurred most rapidly at 20 °C and an alternating temperature with a mean of 15 °C. At constant 15 °C, pupae failed to emerge as adults. Pupae were characterized by a reduced respiration rate, which is typical of a diapausing pupa. When insects were stored at different temperatures for 45 days after pupariation, and then transferred to 25 °C, adult eclosion occurred earlier when the initial temperature was 10 °C than when it was 5 °C or 15 °C. Adult eclosion occurred most synchronously and pupal mortality was lowest when insects were stored at 15 °C for 90 days before incubation at 25 °C. These results strongly suggest thatD. tsuneonis enters a pupal diapause.     

Low Temperature Storage of <Emphasis Type="Italic">Telenomus remus</Emphasis> (Nixon) (Hymenoptera: Platygastridae) and its Factitious Host <Emphasis Type="Italic">Corcyra cephalonica</Emphasis> (Stainton) (Lepidoptera: Pyralidae)

We conducted three bioassays to evaluate the effect of low-temperature storage of eggs (host) and pupae and adults (parasitoid) on the biology and parasitism capacity of the egg parasitoid Telenomus remus (Nixon) (Hymenoptera: Platygastridae). Viable stored Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) eggs were parasitized to the same degree or even higher than fresh eggs when stored until 14 days at 5°C or until 21 days at 10°C. In contrast, the percentage of parasitized sterilized eggs was equal to the control only when stored for 7 and 14 days. Survival of T. remus pupae declined with storage time at both studied temperatures (5 and 10°C). However, after 7 days of storage, survival of pupae was still 86.3 and 64.9% at 10 and 5°C, respectively. The number of adult male survivors remained similar until the fourth storage day at both 5 and 10°C. In contrast, female survival did not differ until day 8 at 10°C or day 6 at 5°C. Parasitism capacity of stored adults was not altered by storage compared with the control. Therefore, we conclude that the maximal storage time at 10°C is 21 days for viable C. cephalonica eggs and 7 days for T. remus pupae, while parasitoid adults should not be stored for more than 4 days at either 5 or 10°C.     

Growth and toxigenicity of Fusaria of the sporotrichiella section as related to environmental factors and culture substrates

Isolates ofFusarium poae, F. sporotrichioides, F. sporotrichioides var.chlamydosporum andF. sporotrichioides var.tricinctum made their best growth on PDA substrates at 24 °C, but good growth was also made at 18 °C and 30 °C. At 35 °C growth made by theF. sporotrichioides var.chlamydosporum was quite good, and superior to that of the other fungi. Moderate growth was made by all fungi at 12 °C and byF. sporotrichioides var.tricinctum also at 6 °C, while growth of the other fungi at that temperature was slight. At low temperatures toxic isolates of all butF. sporotrichioides grew better than non-toxic isolates, and growth of all isolates usually was better in light than in darkness up to temperatures of 18 °C. F. poae andF. sporotrichioides produced highest toxicity on rabbit skins when grown at 5–8 °C,F. sporotrichioides var.tricinctum at 15–20 °C. Darkness always favoured toxin development at all temperatures. In a comparison of 3 liquid substrates, overall toxin production was stronger on a starch substrate than on Czapek's or carbohydrate-peptone substrates. Among grain substrates, barley gave highest overall toxicity, which was again favoured by darkness.F. poae isolates were most toxic when derived from soil,F. sporotrichioides isolates when derived from barley. Further tests with 8 liquid substrates confirmed thatF. poae andF. sporotrichioides produce stronger toxicity at 8 °C than at 25 °C, and substrates favoured toxin production at pH 5.6 more than at pH 3.8 or 7.2. At pH 5.6 the isolates induced marked changes in the pH level of the substrate on which they grew. No relation was found to exist between the vigour of growth made by any of these fungi under various environmental conditions and the severity of the toxiç reaction their extracts produced on rabbit skins.     

Effect of fruit type and storage treatments on the biodeterioration of African pear (Dacryodes edulis (G. Don.) H. J. Lam.)

The storage potential of the African pear (Dacryodes edulis (G. Don.) H. J. Lam.) (Burseraceae) was investigated using four fruit types. At ambient temperatures (28·5–30°C), those enclosed in either paper or polythene bags could be stored satisfactorily for 3–8 days, after which they deteriorated rapidly. Storage life was increased at lower temperatures, but injury due to chilling was observed at −5°C. At 15°C, fruits dipped in palm oil before being packaged were of better quality and retained their firmness longer than fruits dipped in a 500 ppm benlate solution. Storage in moist sawdust, wood-shavings or water were the least effective in extending shelf-life. Variation among fruit types in their response to storage treatment was observed.     

Effect of pollination time,the hour of daytime,pollen storage temperature and duration on pollen viability,germinability, and fruit set of date palm (Phoenix dactylifera L.) cv "Deglet Nour"

Success artificial pollination with viable pollen is crucial process in the production chain of date palms. This study evaluated the impact of pollen storage temperature and duration, pollination time following spathe cracking, and the hour of daytime on pollen viability, germinability, fruit set and yield of 'Deglet Nour' date palm cultivar. In in vitro tests, fresh pollen showed the maximum viability (96.3%) and germination (85%) but it decreased thereafter upon the storage temperature (28, 4 and ?30 °C) and duration (3, 6, 9 and 12 months). In this respect, pollen stored at ?30 °C retained highest viability and germinability followed by those stored at 4 and then at 28 °C. In filed experiments, fruit set was 85, 75, 65, and 45% with pollination using fresh pollen, or pollen stored at ?30, 4 and 28 °C, respectively. Fruit set was 95%, 75%, and less than 50%, for pollination performed on the same day of spathe cracking, 6 and 12 days later, respectively. The highest fruit set percentage and yield/bunch were obtained with pollination performed between 12.0 pm and 15.0 pm in contrast to 8.0–11.0 am or 16.0–17.0.     

Effect of Low Temperature and Rh izospheric Application of Naringenin on Pea-Rhizobium leguminosarum biovar viciae Symbiosis

The production of Tsr factor by Rhizobium leguminosarum bv. viciae was influenced by low temperature (10°C) In the presence of seed exudate collected at 10°C and 25°C or naringenin (10fuM). Root exudate collected at 25°C and naringenin induced Tsr factor in R. leguminosarum causing thick and short root phenotype and root hair curling and deformation of host root. Root exudate collected at 10°C also induced root hair curling but Tsr activity was low. low temperature grown plants had poor nodulation, nitrogen fixation, nitrogen content and total blomass as compared to plants grown at 25°C. Rhizospheric application of naringenin partially alleviated the deleterious effect of low temperature on nodulation status and nodule efficiency.     

Encapsulation, cold storage, and growth of Hibiscus moscheutos nodal segments

Nodal segments of Hibiscus moscheutos (hardy hibiscus) were excised from proliferating axillary shoot cultures and encapsulated in high density sodium alginate hardened by 50 mM CaCl₂. Nodal segments 4 mm long grew as well as and were easier to encapsulate than 8 mm long nodal segments. Although nodal segments grew regardless of the concentration of sodium alginate, 2.75% was determined to produce the highest quality encapsulated nodal segments beads (sufficient alginate coating and ease of use) because of the viscosity produced by the 2.75% sodium alginate solution. When encapsulated segments were stored at 5°C they did not grow in light or darkness. During the first month on fresh proliferation medium under normal incubation conditions following 5°C storage in the dark for up to 24 weeks, root number and root and shoot elongation were inhibited linearly as storage time increased. All encapsulated nodal segments survived 24 weeks of 5°C storage in two separate experiments. In fact, 80% of encapsulated hardy hibiscus nodal segments survived refrigerated storage for 1½ years (78 weeks) and after 3 months on proliferation medium, the nodal segments produced nearly the same length axillary shoots with the same number of axillary nodes per shoot as compared to encapsulated segments either not stored at 5°C or stored for 24 weeks at 5°C. Growth from encapsulated and cold-stored ‘Lord Baltimore’ nodal segments was more vigorous than from ‘Southern Belle’ nodal segments.     

The influence of storage temperature on spore viability of Mattesia trogodermae (Protozoa: Neogregarinida)

The viability of Mattesia trogodermae spores stored at different temperatures was assessed by the percentage infection induced in 30-day-old Trogoderma glabrum larvae. Exposure to 73°C and higher temperatures for 30 min was lethal to the spores. Spores stored at ?19°C survived better than those stored at 26.7°, 3.5°, or ?30°C.     

Investigation into the Potential of Bacteriocinogenic Lactobacillus plantarum BFE 5092 for Biopreservation of Raw Turkey Meat

The bacteriocin-producing Lactobacillus plantarum BFE 5092 was assessed for its potential as a protective culture in the biopreservation of aerobically stored turkey meat. This strain produces three bacteriocins, i.e. plantaricins EF, JK and N. The absolute expression of Lactobacillus plantarum BFE 5092 16S rRNA housekeeping gene, as well as l-ldh, plnEF and plnG genes as determined by quantitative, real-time-PCR, revealed that these genes were expressed to similar levels when the strain was grown at 8 and 30 °C in MRS broth. On turkey meat, Lactobacillus plantarum BFE 5092 did not grow but survived, as indicated by similar viable cell numbers during a 9-day storage period at 8 °C. When inoculated at 1 × 10⁷ CFU/g on the turkey meat and subsequently stored at 10 °C, the culture did again not show good growth. Lactobacillus plantarum BFE 5092 could not inhibit the growth of naturally occurring listeriae or Gram-negative bacteria on the turkey meat at 10 °C, or that of Listeria monocytogenes when it was co-inoculated at a level of 1 × 10⁵ CFU/g. Gene expression analyses showed that the bacteriocin genes were expressed on turkey meat stored at 10 °C. Moreover, the investigation into the absolute expression of the three plantaricin genes of Lactobacillus plantarum BFE 5092 in co-culture with Listeria monocytogenes on turkey meat by qRT-PCR showed that the plantaricin genes were indeed expressed during the low-temperature storage condition. The Lactobacillus plantarum BFE 5092 strain overall could not effectively inhibit L. monocytogenes and therefore it would not make a suitable protective culture for biopreservation of turkey meat stored aerobically at low temperature.     

Ethylene action blockade and cold storage affect ripening of ‘Golden’ papaya fruit

The purpose of this work was to evaluate the effects of ethylene action blockade and cold storage on the ripening of ‘Golden’ papaya fruit. Papayas harvested at maturity stage 1 (up to 15% yellow skin) were evaluated. Half of the fruits, whether treated or not treated with 100 nL L⁻¹ of 1-methylcyclopropene (1-MCP), were stored at 23°C, while the other half were stored at 11°C for 20 days prior to being stored at 23°C. Non-refrigerated fruits receiving 1-MCP application presented a reduction in respiratory activity, ethylene production, skin color development and pectinmethylesterase activity. Even with a gradual increase in ethylene production at 23°C, fruits treated with 1-MCP maintained a high firmness, but presented a loss of green skin color. Cold storage caused a decrease in ethylene production when fruits were transferred to 23°C. The results suggest that pulp softening is more dependent on ethylene than skin color development, and that some processes responsible for loss of firmness do not depend on ethylene.     

Effects of temperature on parameters of root growth relevant to nutrient uptake: Measurements on oilseed rape and barley grown in flowing nutrient solution

Summary Effects of root temperature on the growth and morphology of roots were measured in oilseed rape (Brassica napus L.) and barley (Hordeum vulgare L.). Plants were grown in flowing solution culture and acclimatized over several weeks to a root temperature of 5°C prior to treatment at a range of root temperatures between 3 and 25°C, with common shoot temperature. Root temperature affected root extension, mean radius, root surface area, numbers and lengths of root hairs. Total root length of rape plants increased with temperature over the range 3–9°C, but was constant at higher temperatures. Root length of barley increased with temperature in the range 3–25°C, by a factor of 27 after 20 days. Root radii had a lognormal distribution and their means decreased with increasing temperature from 0.14 mm at 3°C to 0.08 mm at 25°C. The density of root hairs on the root surface increased by a factor of 4 in rape between 3 and 25°C, but in barley the highest density was at 9°C. The contribution of root hairs to total root surface area was relatively greater in rape than in barley. The changes in root system morphology may be interpreted as adaptive responses to temperature stress on nutrient uptake, providing greater surface area for absorption per unit root weight or length.     

Effect of temperature and ripening stages on membrane integrity of fresh-cut tomatoes

The shelf-life of fresh-cut tomatoes mainly depends on loss of tissue integrity and firmness that occurs also in intact fruits after long-term cold storage due to chilling injury. Round-fruit tomatoes (Solanum lycopersicum L.) cv. Jama were stored in 1.1-L plastic (polyethylene) fresh-cut produce containers as 10.0-mm-thick tomato slices and as intact tomatoes at 4 ± 0.5 °C. The aim of this work was to study the loss of membrane integrity and biochemical processes involved in membrane disruption. Electrolyte leakage and lipid peroxidation were studied at different stages of maturity: mature green, pink (PK), fully ripe and two different storage temperatures: 4 and 15 °C. The tomato slices of PK stage stored at 4 °C did not show changes for both parameters, while significant increase in membrane leakage and lipid peroxidation was observed at 15 °C, especially after 24 h of storage. The enzymes showed a simultaneous increase in their activities with a rise in electrolyte leakage and lipid peroxidation after 7 days of storage. Finally, phospholipase C (PLC) and phospholipase D (PLD) were investigated for intact fruit and tomato slices stored at 4 °C. The PLC had higher activity compared with PLD. In conclusion, the loss of membrane integrity in fresh-cut tomatoes is mainly affected by ripening stages, storage temperature and duration. The wounds enhance the PLC and PLD activities and they play a role late during storage.     

Interacting climate change environmental factors effects on Fusarium langsethiae growth,expression of Tri genes and T-2/HT-2 mycotoxin production on oat-based media and in stored oats

This study examined the effect of climate change (CC) abiotic factors of temperature (20, 25, 30 °C), water activity (a_w; 0.995, 0.98) and CO₂ exposure (400, 1000 ppm) may have on (a) growth, (b) gene expression of biosynthetic toxin genes (Tri5, Tri6, Tri16), and (c) T-2/HT-2 toxins and associated metabolites by Fusarium langsethiae on oat-based media and in stored oats. Lag phases and growth were optimum at 25 °C with freely available water. This was significantly reduced at 30 °C, at 0.98 a_w and 1000 ppm CO₂ exposure. In oat-based media and stored oats, Tri5 gene expression was reduced in all conditions except 30 °C, 0.98 a_w, elevated CO₂ where there was a significant (5.3-fold) increase. The Tri6 and Tri16 genes were upregulated, especially in elevated CO₂ conditions. Toxin production was higher at 25 °C than 30 °C. In stored oats, at 0.98 a_w, elevated CO₂ led to a significant increase (73-fold) increase in T2/HT-2 toxin, especially at 30 °C. Nine T-2 and HT-2 related metabolites were detected, including a new dehydro T-2 toxin (which correlated with T-2 production) and the conjugate, HT-2 toxin, glucuronide. This shows that CC factors may have a significant impact on growth and mycotoxin production by F. langsethiae.