Large Green Fruit Research Articles

Expression patterns of four key genes involved in strawberry eugenol synthesis under abiotic stresses

Eugenol is an important phenylpropanoid in strawberry and the accumulation is affected by various abiotic stresses. In this study, the expression patterns of two transcription factors (TFs) (FaMYB10 and FaEOBII) and two synthetic genes (FaEGS1 and FaEGS2) involved in eugenol synthesis were characterized in Fragaria × ananassa cv. ‘Xiaobai’. Sequence analysis showed the four genes contained several cis-acting elements that were related to phytohormones and environmental stress signal responsiveness. FaEGS1 and FaEGS2 were clustered in the same group clade. The four genes were expressed in all analysed tissues and, in particular, expressed to higher relative expression levels in leaves. The expression of FaEGS1, FaEGS2, and FaEOBII was the highest in large green fruits, and FaMYB10 had the highest expression in red-ripening fruits. The amount of eugenol showed a stage-specific profile. The expression of these four genes was up-regulated by ethephon (ETH), dark, drought, heat, and salt treatments accompanied by the increase of eugenol production. Concentration and timing of cadmium treatment affected gene expression. Cadmium inhibited the expression of FaEGS1 and FaEOBII, but significantly promoted the expression of FaEGS2 and FaMYB10 and eugenol content. The results provide a basis for elucidating the role of these genes in response to abiotic stresses, and regulating the accumulation of eugenol, an important constituent of volatile compounds in many economically important and aromatic plants.

Volatile constituents and ellagic acid formation in strawberry fruits of selected cultivars

Strawberries (Fragaria × ananassa Duch.) are considered a functional food and pleasing fruit in China, mainly because of their high concentration of ellagic acid (EA) and their aroma. A total of 127 volatile compounds were identified by HS–SPME–GC–MS. Changes in volatile constituents and EA were investigated in 50 strawberry cultivars in the red-ripening stage and in 6 cultivars, including ‘Benihoppe’, ‘Snow White’, ‘Yanli’, ‘Kaorino’, ‘Tokun’, and ‘Xiaobai’, at four developmental stages. The results indicated that the components and amounts of volatile compounds and EA markedly varied among and within cultivars. Through multivariate statistical analysis of the volatile compounds, 50 cultivars were divided into 4 clusters. Aromatic components that affected the cluster formation of cultivars were detected. Volatile compounds varied quantitatively among the 6 varieties during the developmental stages, and distinct changes were observed in both red-turning fruits and red-ripening fruits compared with white fruits. Except for ‘Xiaobai’, which showed the highest EA content at the red-ripening stage, the other 5 cultivars exhibited the highest EA level at the large green fruit stage. Partial least squares–discriminant analysis (PLS–DA) of the profiles of volatile compounds indicated that large green fruits were characterized by EA and aldehydes; white fruits were characterized by ketones and alkanes; and red-ripening fruits were characterized by esters, acids, furans, and alcohols. The results contribute new and important information to breeding programs and the desirable cultivation of strawberry production.

Methyl Jasmonate Applications From Flowering to Ripe Fruit Stages of Strawberry (Fragaria × ananassa 'Camarosa') Reinforce the Fruit Antioxidant Response at Post-harvest.

Preharvest applications of methyl jasmonate (MeJA) have been shown to improve post-harvest fruit quality in strawberry fruit. However, the effectiveness of consecutive field applications at different phenological stages on the reinforcement of the antioxidant capacity remains to be analyzed. To determine the best antioxidant response of strawberry (Fragaria × ananassa ‘Camarosa’) fruit to different numbers and timing of MeJA applications, we performed three differential preharvest treatments (M1, M2, and M3) consisted of successive field applications of 250 μmol L–1 MeJA at flowering (M3), large green (M2 and M3), and ripe fruit stages (M1, M2, and M3). Then, we analyzed their effects on fruit quality parameters [firmness, skin color, soluble solids content/titratable acidity (SSC/TA) ratio, fruit weight at harvest, and weight loss] along with anthocyanin and proanthocyanidin (PA) accumulation; the antioxidant-related enzymatic activity of catalase (CAT), guaiacol peroxidase (POX), and ascorbate peroxidase (APX); the total flavonoid and phenolic contents, antioxidant capacity, and ascorbic acid content (AAC) during post-harvest storage (0, 24, 48, and 72 h). We also evaluated the effect on lignin, total carbon and nitrogen (%C and N), lipid peroxidation, and C and N isotopes signatures on fruits. Remarkably, the results indicated that MeJA treatment increases anthocyanin and PA contents as well as CAT activity in post-harvest storage, depending on the number of preharvest MeJA applications. Also, M3 fruit showed a higher AAC compared to control at 48 and 72 h. Noticeably, the anthocyanin content and CAT activity were more elevated in M3 treatment comparing with control at all post-harvest times. In turn, APX activity was found higher on all MeJA-treated fruit independent of the number of applications. Unlike, MeJA applications did not generate variations on fruit firmness and weight, lignin contents,% C and N, and in lipid peroxidation and water/nitrogen use efficiency according to C and N isotope discrimination. Finally, we concluded that an increasing number of MeJA applications (M3 treatment) improve anthocyanin, PA, AAC, and CAT activity that could play an essential role against reactive oxygen species, which cause stress that affects fruits during post-harvest storage.

Priming of Defense Systems and Upregulation of MYC2 and JAZ1 Genes after Botrytis cinerea Inoculation in Methyl Jasmonate-Treated Strawberry Fruits.

Several attempts have been made to study the effects of methyl jasmonate (MeJA) on plants in the past years. However, the comparative effects of the number and phenological time of MeJA applications on the activation of defense systems is currently unknown in strawberries. In the present research, we performed three field treatments during strawberry (Fragaria × ananassa ‘Camarosa’) fruit development and ripening which consisted of differential MeJA applications at flowering (M3), and the large green (M2 and M3) and red ripe (M1, M2, and M3) fruit stages. We also checked changes in gene expression related to plant defense against Botrytis cinerea inoculation post-harvest. In M3 treatment, we observed an upregulation of the anthocyanin and lignin contents and the defense-related genes, encoding for chitinases, β-1,3-glucanases and polygalacturonase-inhibiting proteins, after harvest (0 hpi), along with the jasmonate signaling-related genes FaMYC2 and FaJAZ1 at 48 h after B. cinerea inoculation (48 hpi) during postharvest storage. Although we did not find differences in gray mold incidence between the MeJA treatments and control, these results suggest that preharvest MeJA treatment from the flowering stage onwards (M3) primes defense responses mediated by the upregulation of different defense-related genes and retains the upregulation of MYC2 and JAZ1 at 48 hpi.

Annona cherimola Seed Extract Activates Extrinsic and Intrinsic Apoptotic Pathways in Leukemic Cells.

Annona cherimola Mill is a large green fruit with black seeds widely known to possess toxic properties due to the presence of Annonaceous acetogenins. The present study investigates the anti-cancer properties of an Annona cherimola Mill ethanolic seed extract on Acute Myeloid Leukemia (AML) cell lines in vitro and elucidates the underlying cellular mechanism. The anti-proliferative effects of the extract on various AML cell lines and normal mesenchymal cells (MSCs) were assessed using WST-1 viability reagent. The pro-apoptotic effect of the extract was evaluated using Annexin V/PI staining and Cell Death ELISA. The underlying mechanism was deciphered by analyzing the expression of various proteins using western blots. Treatment with an A. cherimola seed ethanolic extract promotes a dose- and time-dependent inhibition of the proliferation of various AML cell lines, but not MSCs. Positive Annexin V staining, as well as DNA fragmentation, confirm an increase in apoptotic cell death by upregulating the expression of pro-apoptotic proteins which control both intrinsic and extrinsic pathways of apoptosis. GC/MS analysis revealed the presence of phytosterols, in addition to other bioactive compounds. In conclusion, Annona cherimola Mill seed extract, previously known to possess a potent toxic activity, induces apoptosis in AML cell lines by the activation of both the extrinsic and the intrinsic pathways.

Optimization and standardization of transient expression assays for gene functional analyses in strawberry fruits

Strawberry is increasingly used as a model plant for research on fruit growth and development. The transient gene manipulation (TGM) technique is widely used to determine the function of plant genes, including those in strawberry fruits. However, its reliable application for the precise identification of gene function has been difficult owing to the lack of conditional optimization. In this study, we found that successful transient gene manipulation requires optimization, with the vector type, temperature, and fruit developmental stage being three major factors determining success. Notably, we found that transient gene manipulation was feasible only from the large green fruit stage onwards, making it especially suitable for identifying genes involved in strawberry fruit ripening. Furthermore, we established a method called percentage difference of phenotype (PDP), in which the functional effect of a gene could be precisely and efficiently identified in strawberry fruits. This method can be used to estimate the functional effect of a gene as a value from 0 to 100%, such that different genes can be quantitatively compared for their relative abilities to regulate fruit ripening. This study provides a useful tool for accelerating research on the molecular basis of strawberry fruit ripening.

Transcriptome profiling by RNA-Seq reveals differentially expressed genes related to fruit development and ripening characteristics in strawberries (Fragaria × ananassa).

Strawberry (Fragaria × ananassa) is an ideal plant for fruit development and ripening research due to the rapid substantial changes in fruit color, aroma, taste, and softening. To gain deeper insights into the genes that play a central regulatory role in strawberry fruit development and ripening characteristics, transcriptome profiling was performed for the large green fruit, white fruit, turning fruit, and red fruit stages of strawberry. A total of 6,608 differentially expressed genes (DEGs) with 2,643 up-regulated and 3,965 down-regulated genes were identified in the fruit development and ripening process. The DEGs related to fruit flavonoid biosynthesis, starch and sucrose biosynthesis, the citrate cycle, and cell-wall modification enzymes played important roles in the fruit development and ripening process. Particularly, some candidate genes related to the ubiquitin mediated proteolysis pathway and MADS-box were confirmed to be involved in fruit development and ripening according to their possible regulatory functions. A total of five ubiquitin-conjugating enzymes and 10 MADS-box transcription factors were differentially expressed between the four fruit ripening stages. The expression levels of DEGs relating to color, aroma, taste, and softening of fruit were confirmed by quantitative real-time polymerase chain reaction. Our study provides important insights into the complicated regulatory mechanism underlying the fruit ripening characteristics in Fragaria × ananassa.

Olive Fruit Fly (Diptera: Tephritidae) in California Table Olives, USA: Invasion, Distribution, and Management Implications

Olive fruit fly, Bactrocera oleae (Rossi), was discovered in California in late 1998. Thereafter, intensive research was conducted to develop pest control methods in table olives grown for canned fruit. The life history of olive fruit fly was elucidated, and the distribution and abundance of the adults determined through trapping programs. Olive samples from noncommercial trees were collected from 2002 through 2013 in different locations to determine the maximum number of larvae per fruit. Larvae were most abundant in September and October and ranged from <0.5 to 10 per fruit. The date of maximum fruit infestations may differ annually due to the amount of fruit set, fruit size, and weather. Very high numbers of larvae were collected from large green fruit (≥4 g), whereas smaller fruit (∼2–3 g) supported fewer insects. High larval numbers were found in fruit from areas with cooler summer weather than in fruit from the hot inland valleys. Olive fruit fly larval populations were prevalent in locations with high summer temperatures when buffered by cool marine air flow or slightly higher elevations from the inland valley floor. High larval infestations were found at an arid location with hot summers, suggesting that olive fruit fly may adapt to such conditions. Infested fruit was collected from the same locations in subsequent years, and the proximity of commercial olive orchards may enhance susceptibility to future infestation. Control methods are summarized, including intensive biological control programs and new techniques such as bait stations considered for pest management programs. Basic cultural practices such as removal of nonharvested fruit that support multiple generations, timing of harvest to avoid adult activity, and elimination of standing water required by olive fruit fly adults for survival would be of major importance in reducing pest populations.

ABA and UV-C effects on quality, antioxidant capacity and anthocyanin contents of strawberry fruit (Fragaria ananassa Duch.)

Effects of 1mM abscisic acid (ABA) and 4.1kJ/m2 UV-C radiation on quality, antioxidant capacity, anthocyanin contents, and anthocyanin biosynthetic enzyme activities of large green strawberry fruit stored at 20°C were evaluated. Results showed that ABA promoted color formation, firmness decrease, soluble solids content and anthocyanin accumulation while UV-C inhibited these processes. Activities of phenylalanine ammonia-lyase, tyrosine ammonia-lyase and p-coumarate ligase were immediately upregulated by approximately 50% with UV-C radiation but were inhibited, including dihydroflavonol 4-reductase especially on day 3 or 4. UV-C radiation had little effect on activity of cinnamate 4-hydroxylase (C4H). ABA enhanced activities of anthocyanin biosynthetic enzymes except C4H. These data indicated that the stimulatory effect of ABA on strawberry anthocyanin accumulation was related to enhancement of biosynthetic enzyme activities, while the effects of UV-C were more transient. In addition, it appeared that C4H was not a rate-limiting enzyme in the strawberry anthocyanin biosynthesis pathway.

Isolation and characterization of two YUCCA flavin monooxygenase genes from cultivated strawberry (Fragaria × ananassa Duch.)

In strawberry (Fragaria × ananassa Duch.), auxin has been recognized as the main signal molecule coordinating the growth and initiation of ripening of fruits. The molecular mechanism regulating auxin biosynthesis in strawberry remains unknown. This project reports two YUCCA flavin monooxygenase genes FaYUC1-2 isolated from cultivated strawberry. FaYUC1 and FaYUC2 are most homologous to AtYUC6 and AtYUC4, respectively. Significant expression of FaYUC1-2 is found in vegetative meristems and reproductive organs, with overlapping but distinct patterns. During fruit development, both transcripts of FaYUC1 and FaYUC2 in achenes reach a peak around large green fruit (G2) stage, but the sudden rise in FaYUC2 transcript level is much steeper and begins earlier than that in FaYUC1. FaYUC2 is also obviously expressed in the receptacles from green fruits, hinting another auxin source for receptacle development, other than achenes. FaYUC1 over-expression Arabidopsis exhibits typical auxin hyper-accumulation phenotype in many aspects, such as the narrow and downward curled leaves, strong apical dominance, short and hairy root. It is also severely sterile, due to the disruption of floral meristems initiation and floral organs development. Transgenic analysis indicates that strawberry YUC gene may hold conserved role in auxin biosynthesis like their homologs in other plants. Integrated with the spatiotemporal expression features, these results led us to propose that FaYUC1-2 may involve in many developmental processes including flower and fruit development in strawberry. This paper is the first report of isolation and characterization of strawberry auxin biosynthesis genes. And their conserved functions in auxin biosynthesis were confirmed after ectopic expression.

Molecular Characterization of a Strawberry FaASR Gene in Relation to Fruit Ripening

BackgroundABA-, stress- and ripening-induced (ASR) proteins have been reported to act as a downstream component involved in ABA signal transduction. Although much attention has been paid to the roles of ASR in plant development and stress responses, the mechanisms by which ABA regulate fruit ripening at the molecular level are not fully understood. In the present work, a strawberry ASR gene was isolated and characterized (FaASR), and a polyclonal antibody against FaASR protein was prepared. Furthermore, the effects of ABA, applied to two different developmental stages of strawberry, on fruit ripening and the expression of FaASR at transcriptional and translational levels were investigated.Methodology/Principal Findings FaASR, localized in the cytoplasm and nucleus, contained 193 amino acids and shared common features with other plant ASRs. It also functioned as a transcriptional activator in yeast with trans-activation activity in the N-terminus. During strawberry fruit development, endogenous ABA content, levels of FaASR mRNA and protein increased significantly at the initiation of ripening at a white (W) fruit developmental stage. More importantly, application of exogenous ABA to large green (LG) fruit and W fruit markedly increased endogenous ABA content, accelerated fruit ripening, and greatly enhanced the expression of FaASR transcripts and the accumulation of FaASR protein simultaneously.ConclusionsThese results indicate that FaASR may be involved in strawberry fruit ripening. The observed increase in endogenous ABA content, and enhanced FaASR expression at transcriptional and translational levels in response to ABA treatment might partially contribute to the acceleration of strawberry fruit ripening.

Expression and regulation of the early auxin-responsive Aux/IAA genes during strawberry fruit development

The plant hormone auxin transcriptionally activates Aux/IAA genes. Auxin plays an important role in regulating fruit growth and ripening of strawberry and Aux/IAA genes have been extensively studied in Arabidopsis, rice and tomato, but little information is available on strawberry fruit. In the present work, two full-length of early auxin-responsive Aux/IAA genes, termed FaAux/IAA1 and FaAux/IAA2 respectively, were isolated and characterized from strawberry fruit. Moreover, the expression profiles of two FaAux/IAA genes during fruit development, and the effect of naphthalene acetic acid (NAA) on their expressions of fruits at two different developmental stages were also investigated. The results showed that the levels of FaAux/IAA1 and FaAux/IAA2 transcripts were very high at early stage of fruit development, and decreased sharply at ripening stage (after white stage). In addition, NAA applied at the stage of large green and white fruit obviously increased the accumulations of FaAux/IAA1 and FaAux/IAA2 transcripts. These data suggested that the expressions of both FaAux/IAA1 and FaAux/IAA2 genes were likely to be involved in early fruit development, and the enhancement of FaAux/IAAs transcripts might be attributed at least or partially to auxin-induced fruit growth and delayed fruit ripening of strawberry.

Isolation of genes differentially expressed during development and ripening of Fragaria chiloensis fruit by suppression subtractive hybridization

Fragaria chiloensis, the native Chilean strawberry, is noted for its good fruit quality characters. However, it is a highly perishable fruit due to its rapid softening. With the aim to screen for genes differentially expressed during development and ripening of strawberry fruit, the subtractive suppressive hybridization (SSH) methodology was employed. Six libraries were generated contrasting transcripts from four different developmental stages. A set of 1807 genes was isolated and characterized. In our EST collection, approximately 90% of partial cDNAs showed significant similarity to proteins with known or unknown function registered in databases. Among them, proteins related to protein fate were identified in a large green fruit library and protein related with cellular transport, cell wall-related proteins, and transcription regulators were identified in a ripe fruit library. Thirteen genes were analyzed by qRT-PCR during development and ripening of the Chilean strawberry fruit. The information generated in this study provides new clues to aid the understanding of the ripening process in F. chiloensis fruit.

Pectin methylesterases induce an abrupt increase of acidic pectin during strawberry fruit ripening

The decrease of strawberry (Fragariaxananassa Duch.) fruit firmness observed during ripening is partly attributed to pectolytic enzymes: polygalacturonases, pectate lyases and pectin methylesterases (PMEs). In this study, PME activity and pectin content and esterification degree were measured in cell walls from ripening fruits. Small green, large green, white, turning, red and over-ripe fruits from the Elsanta cultivar were analyzed. Using the 2F4 antibody directed against the calcium-induced egg box conformation of pectin, we show that calcium-bound acidic pectin was nearly absent from green and white fruits, but increased abruptly at the turning stage, while the total pectin content decreased only slightly as maturation proceeded. Isoelectrofocalisation performed on wall protein extracts revealed the expression of at least six different basic PME isoforms. Maximum PME activity was detected in green fruits and steadily decreased to reach a minimum in senescent fruits. The preliminary role of PMEs and subsequent pectin degradation by pectolytic enzymes is discussed.

Reproductive biology of theIlexspecies (Aquifoliaceae) in Hong Kong, China

Fourteen wild species of shrubs and trees in the dioecious genus Ilex occur in Hong Kong (22°N, 114°E). All species flowered and formed fruits once each year. Sex ratios at flowering were male biased in all but one large population studied and, in most cases, this bias could not be explained by earlier flowering in males or higher female mortality. Apis cerana accounted for &gt;87% of flower visits in all species and there was a significant positive relationship across species between the number of visits per flower per hour and the estimated mean number of flowers on a plant. The large green fruits of Ilex chapaensis Merr. were consumed only by masked palm civets, Paguma larvata, while the red or black fruits of other species were consumed by birds. The rate of fruit removal across species was positively related to sugar content and negatively related to phenolic and saponin contents. The mean number of pyrenes per fruit was 4.0–6.2 and the mean percentage of pyrenes containing seeds was 49%–90%. Most embryos were immature (heart shaped) at fruit maturity, but &lt;50% of embryos developed further in some species. Floral investment was 0.93–5.84 times higher in male plants, but total reproductive investment was 0.62–8.3 higher in females.

Characterization of peroxidase-mediated chlorophyll bleaching in strawberry fruit

Peroxidase (POX) from strawberry fruits was analyzed for its capacity to bleach chlorophyll. The partially purified enzyme preperation catalyzed the bleaching of chlorophylls and their derivatives in the presence of H 2O 2 and phenolic compounds. The optimal reaction conditions were 35 °C, pH 5.2 and ionic strength equal to 0.2. The maximum activity was observed at 1 mM of H 2O 2, while higher concentrations inhibited enzyme activity. Compounds with a high affinity to the heme group, radical scavengers and reducing agents, showed an inhibitory effect. Phenolic compounds such as umbelliferone, naringenin and p-substituted monophenols acted as cofactors. Instead, other phenolic compounds tested such as caffeic acid, catechin, ellagic acid, esculin and quercetin inhibited the activity of POX on chlorophylls. Phenolic compounds extracted from strawberry fruits showed an inhibitory effect on POX-chlorophyll bleaching activity, although this effect decreased markedly during ripening. POX showed higher affinity for compounds derived from chlorophyll a than from chlorophyll b , and the enzyme preferentially degraded chlorophyll derivatives with the Mg 2+ ion present and the phytol group removed. The POX-chlorophyll bleaching activity was found in all ripening stages from small green to ripe, the highest activity corresponding to large green fruits.

Two Different Endo-β-1,4-Glucanases Contribute to the Softening of the Strawberry Fruits

The expression of different endo-(β-l,4-glucanases (EGases) and the ultrastructural details of the cell wall dismantling were studied throughout the development of the strawberry fruits. Detectable enzyme activity is first observed in large green fruits, but a steep increase occurs in white fruits when the ripening process proper starts. This process is then accompanied by a further increase in EGase activity which appears to be doubled in red ripe fruits. Two isoforms with different isoelectric points (pI 7.9 and 9.0, respectively) contribute to the observed enzyme activity, and both isoenzymes increase in activity as fruits ripen. Two cDNA fragments, encoding two divergent endo-(β-l,4-glucanases (faEGlO and faEG30, respectively), were obtained by RT-PCR and the expression of their related mRNAs examined by northern analysis. faEG30-related transcripts start to be detected in large green fruits, while faEGlO expression is detected in white fruits. Thereafter, the amount of both EGase mRNAs increases throughout the ripening process up to the stage of red ripe fruits. The fine structure of the cell wall weakening which occurs during the ripening is well in accordance with the above described biochemical and molecular data.

A novel E-type endo-beta-1,4-glucanase with a putative cellulose-binding domain is highly expressed in ripening strawberry fruits.

Two full-length cDNA clones (faEG1 and faEG3, respectively) have been isolated by screening a cDNA library representing transcripts from red strawberry fruits. Southern blot analysis of genomic DNA suggests that the strawberry endo-beta-1,4-glucanases (EGases) are encoded by a multigene family. The cognate genes are predominantly expressed during the ripening process proper, although, in the case of faEG3, some expression has also been observed in large green fruits and, at low amounts, in young vegetative green tissues. In agreement with other ripening-related genes in strawberry, also the expression of faEG1 and faEG3 is down-regulated by treatment with an auxin analogue (1-naphthaleneacetic acid, NAA). Differences in temporal expression of the two EGase genes in fruits are not accompanied by differences in spatial expression. The pattern of expression and the sequence characteristics of the two polypeptides suggest that the two strawberry EGases operate in a synergistic and coordinate manner. The protein encoded by faEG1 looks like one of the usual higher-plant EGases (average molecular mass of 54 kDa), while the protein encoded by faEG3 has a greater deduced molecular mass (about 68 kDa) due to the presence of an extra peptide of about 130 amino acids at the C-terminus. Such unusual peptide shows some features also found in microbial cellulases and contains a putative cellulose-binding domain. We propose that the faEG3-encoded EGase might especially hydrolyse the xyloglucans coating the cellulose microfibrils, thus rendering the cell wall more susceptible to the subsequent hydrolytic activity of the faEG1-encoded EGase.

Disease Progress of Black Dot on Tomato Roots and Reduction in Incidence with Foliar Applied Fungicides.

Progression of black dot caused by Colletotrichum coccodes was determined at regular intervals on roots of processing tomatoes growing in a naturally infested field. In 1993 and 1994, C. coccodes was first isolated from tomato roots 30 and 37 days after transplanting, respectively, which corresponded to the opening of flowers in the first flower clusters. Black dot incidence increased rapidly from the time when large green fruit were present to production of mature red fruit. In both years, C. coccodes was isolated from the roots of 97% of the plants at the postharvest sampling date (162 days after transplanting). Areas under the incidence disease progress curves were not significantly different in the 2 years of study (1993 = 83.5, 1994 = 86.9). Root decay was severe at the postharvest sampling, and sclerotia of C. coccodes were abundant on the roots. C. coccodes was isolated from 38 and 44% of the root segments in 1993 and 1994, respectively. Areas under the disease progress curves for infected root segments were not significantly different in the 2 years of study (1993 = 25.8, 1994 = 33.9). In a separate study, chlorothalonil (2.5 kg/ha) or mancozeb (1.68 kg/ha) was applied at 7-, 10-, or 14-day intervals to tomato plants. Recovery of C. coccodes from root segments at harvest (113 to 118 days after transplanting) was significantly reduced in the chlorothalonil 7- or 10-day and mancozeb 10-day interval treatments in both years. However, the percentage of plants with black dot was not consistently reduced by fungicide applications.

Ontogenetic changes in water in cherry tomato fruits measured by nuclear magnetic resonance imaging

Changes in water status of intact developing cherry tomato fruits were followed by 1H NMR imaging and 1H NMR spectroscopy. In small green fruits, large amounts of water were located in the epidermis and neighbouring cells, and in seed envelopes and seeds. High mobility water with long spin-lattice relaxation times ( T 1) in the seeds of small green fruits disappeared as the fruit grew. The content of high mobility water in locular cavities, including seed envelopes, increased as ontogeny advanced. Low mobility water (short T 1) in the pericarp and dissepiments of the small and large green fruits increased in quantity and mobility during maturation. In some of the several water compartments in large green fruits water content declined during maturation. Changes in the physical state of water appeared to reflect changes in the physiology of the fruits. The mobility of sugars increased during fruit ripening.