Biology of the Two-Spotted Spider Mite on Strawberry Plants

The two-spotted spider mite, Tetranychus urticae Koch, is commonly found on strawberry crops (Fragaria x ananassa). Strawberry plants have defensive mechanisms, which in turn influence the behavior of herbivores. The oviposition and development of the two-spotted spider mite were evaluated on the leaf disks of the cultivars ‘Aromas,’ ‘Camarosa,’ ‘Camino Real,’ ‘Diamante,’ ‘Diamante 10,’ ‘Diamante 50,’ ‘Festival,’ and ‘Seascape.’ It was observed that on cultivars such as ‘Aromas,’ ‘Camarosa,’ and ‘Seascape,’ immature survivorship was higher, but no difference was found during the developmental period from egg to adult of T. urticae. The immature development time was also longer on ‘Camarosa.’ Females laid more eggs on ‘Seascape’ (8.4 eggs/day), and the least on ‘Camarosa’ (1.0 egg/day). Mortality was higher at the larval stage and reached more than 50% in three cultivars ‘Camarosa,’ ‘Diamante,’ and ‘Seascape.’ Thus, the cultivars ‘Camarosa,’ ‘Diamante,’ and ‘Seascape’ were the ones that mostly affected the survival, development, and reproduction of T. urticae.     

Intraspecific variation in alkaloid profile of four lupine species with implications for the pea aphid probing behaviour

The alkaloid profile of white lupine Lupinus albus L. cv. ‘Boros’ and ‘Butan’, narrow-leaf lupine L. angustifolius L. cv. ‘Bojar’, ‘Graf’, ‘Karo’, ‘Mirela’, and ‘Sonet’, yellow lupine L. luteus L. cv. ‘Dukat’, ‘Parys’, ‘Perkoz’, and ‘Talar’, and wild species big-leaf lupine L. polyphyllus Lindl. was studied. The pea aphid Acyrthosiphon pisum Harris probing behaviour was monitored using the electrical penetration graph (EPG) technique.Four types of feeding behaviour were recognized. First, on highly acceptable L. luteus cv. ‘Dukat’, the total and mean duration of probing, time to reach phloem phase, and the duration of the first phloem phase were comparable to those in aphids on control plant Pisum sativum. Second, on partially acceptable L. luteus cv. ‘Talar’, pathway activities were slightly impeded, and the probes were more numerous and slightly shorter than on control plants. The phloem phase occurred sporadically, and feeding was terminated early after a brief period of ingestion. Third, on unpalatable but acceptable L. angustifolius cv. ‘Bojar’ and ‘Sonet’, and L. luteus cv. ‘Parys’ and ‘Perkoz’, the probes were numerous and usually epidermal. The phloem phase occurred rarely, and when it did, it was short and consisted mainly of watery salivation. Finally, on unacceptable L. albus cv. ‘Boros’ and ‘Butan’, L. angustifolius cv. ‘Graf’, ‘Karo’, ‘Mirela’, and L. polyphyllus, total probing time and individual probes were short and phloem phase did not occur.Eighteen alkaloids were identified: one piperidine alkaloid (ammodendrine), one indole (gramine), ten quinolizidine alkaloids (one tricyclic and nine tetracyclic compounds), and six esters. All lupine varieties that contained lupanine, its derivatives and especially their esters appeared to be unacceptable to the pea aphid, independent of the total concentration of any specific lupanine alkaloid. In contrast, sparteine and its derivatives did not seem to affect aphid probing significantly.     

A SNP in the promoter region of the<Emphasis Type="Italic">VvmybA1</Emphasis> gene is responsible for differences in grape berry color between two related bud sports of grape

The VvmybA1 gene in grape (Vitis vinifera) plays a key role in the biosynthesis of anthocyanin. The grape cultivars, ‘Benitaka’ (red color) and ‘Brazil’ (black color) were the result of a bud mutation. ‘Benetika’ was derived from ‘Italia’ (green color) and ‘Brazil’ was developed from ‘Benetika’. Single sequence repeat (SSR) molecular marker analysis was performed in order to demonstrate that the three cultivars have a common pedigree. A sequence analysis of the promoter region and coding sequence of VvmybA1 revealed a base substitution between ‘Benitaka’ and ‘Brazil’ in the promoter region and a deletion of a large DNA fragment in the promoter region of ‘Italia’. Anthocyanin content and expression of the VvmybA1 and UFGT genes in ‘Brazil’ were higher than in ‘Benitaka’ and barely detectable in ‘Italia’. A transient expression system was used to introduce VvmybA1 driven by the three different promoters present in ‘Italia’, ‘Brazil’, and ‘Benitaka’ into somatic embryos of ‘Centennial Seedless’ (Vitis vinifera L.) by Agrobacterium-mediated transformation. This resulted in the production of red cells in the embryos transformed with the constructs of VvmybA1 from ‘Brazil’ and ‘Benitaka’ and no color production in embryos transformed with the VvmybA1 construct from ‘Italia’. In addition, the embryos transformed with the ‘Brazil’ construct had more red color than the embryos transformed with the ‘Benitaka’ construct. These results suggested that a SNP mutation in the promoter region of VvmybA1 in ‘Benitaka’ (red color) was responsible for the color change displayed by ‘Brazil’ (black color).     

Resistance of Citrus and Related Genera to Diaphorina citri Kuwayama (Hemiptera: Liviidae)

The present study was developed to evaluate the resistance of the following genotypes of Citrus and related genera to this pest: ‘Pera,’ ‘Natal’, and ‘Washington Navel’ oranges (Citrus sinensis), ‘Marsh Seedless’ grapefruit (Citrus paradisi), hardy orange ‘Rubidoux’ (Poncirus trifoliata), kumquat (Fortunella margarita Swingle), citrumelo ‘Swingle’ (C. paradisi x P. trifoliata), and citrange ‘Troyer’ (P. trifoliata x C. sinensis). The experiments were performed in greenhouses with plants grafted onto ‘Rangpur’ lime (Citrus limonia) and placed individually in voile cages. The preference for oviposition in a no-choice test, and the effect of genotype were evaluated. The egg-adult cycle was monitored to determine the effect of genotype on the biology of the insect. Poncirus ‘Rubidoux’ was the least preferred genotype for oviposition; reduced number of eggs was also found to occur on citrange ‘Troyer’, and ‘Marsh Seedless’ was the genotype with the most eggs. No significant variation in the duration of the embryonic period was observed; however, a difference in the viability of eggs was found, with the lowest egg viabilities on ‘Swingle.’ Kumquat and ‘Marsh Seedless’ genotypes were correlated with increased durations of the nymphal phase, however, there was no difference in the survival of this phase. Fecundity of females on ‘Troyer’, ‘Swingle’, and kumquat was reduced. Considering all of the evaluated parameters, it was concluded that cultivars of sweet orange are the most susceptible genotypes to Diaphorina citri. Regarding oviposition, P. trifoliata ‘Rubidoux’ showed resistance of the antixenosis type.     

Expression and functional analysis of a novel MYB gene, MdMYB110a_JP, responsible for red flesh, not skin color in apple fruit

We have succeeded in isolating an MdMYB110a_JP gene responsible for a red-fleshed trait from a fruit of apple cultivar ‘JPP35’ (‘Jonathan’ × ‘Pink Pearl’). The isolated MdMYB110a_JP gene was located on chromosome (ch.) 17, which was different from the location of known MdMYB1/10 gene of ch.9, and ‘JPP35’ and ‘Pink Pearl’ did not contain the known R ₆ :MdMYB10 allele responsible for the red-skin and red-fleshed trait. The MdMYB110a_JP was expressed strongly and weakly in the cortex and core of ‘JPP35’ fruit, respectively, at the time of coloring start in flesh, and also weakly in flower buds. Following the MdMYB110a_JP expression, the expression of the genes, MdCHS and MdLDOX, that encode the enzymes of the flavonoid pathway, was induced in flesh of ‘JPP35’ in accordance with anthocyanin accumulation. In contrast, the MdMYB110a_JP gene was not expressed in any tissues in red-skin and white-fleshed ‘Fuji’, and in red-skin and red-fleshed ‘Maypole’. Instead, MdMYB1-1 allele responsible for red-skin trait was expressed in red-skin of ‘Fuji’ and ‘JPP35’, and R ₆ :MdMYB10 allele responsible for red-skin and red-flesh trait was expressed in red-core and red-cortex in ‘Maypole’ as expected. Moreover, 35S:MdMYB110a_JP transgenic apple ‘JM2’ showed a red-foliage phenotype depending on the MdMYB110a_JP expression level. From the results, it was strongly suggested that the red-fleshed phenotype of ‘JPP35’ fruit was caused by up-regulation of the genes of anthocyanin pathway induced by the MdMYB110a_JP gene.     

Stimulatory effect of cycloheximide on the infection of hyacinth and tulip bulbs byPenicillium sp.

Treating scooped out bulbs of hyacinths (Hyacinthus orientalis L. cv. ‘Lady Derby’, cv. ‘Pink Pearl’, cv. ‘Delft Blue’) and tulips (Tulipa gesneriana hort. cv. ‘Oxford’) with cycloheximide stimulated strongly the infection of the tissues of the bulbs byPenicillium sp. The possible mechanism of such an activity of cycloheximide is discussed.     

On the evolution of ‘Indian Bison type’ strains of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne's disease (JD) in animals, has also been linked with Crohn's disease in human beings. Lack of indigenous diagnostics and vaccine hampered control of JD in India. Designing effective control strategies require thorough understanding of the etiological agent at phenotypic and molecular levels. On the basis of cultural phenotypes and IS1311 PCR-REA typing, MAP strains have been genotyped as ‘Cattle type’, ‘Sheep type’ and ‘Bison type’. Information exists on genetic differences and comparative evolution of ‘Cattle type’ and ‘Sheep type’ strains after divergence from M. avium; however, emphasis has been little on ‘Bison type’ strains. Recently, a new ‘Indian Bison type’ genotype has been reported as principal strain infecting different animal species and human beings in India. The study analyzed few genetic markers to have inferences on the molecular evolution of native MAP isolates belonging to ‘Bison type’ genotype. Results pointed towards recent evolution of ‘Bison type’ genotype.     

Identification and analysis of cold stress-inducible genes in Korean rapeseed varieties

The rapeseed plant (Brassica napus) is one of the top five oil-producing crops in the world. However, its potential for global cultivation is limited due to its sensitivity to cold. We selected five varieties of rapeseed popular in Korea and analyzed their sensitivity to cold stress. Three — ‘Naehan’, ‘Sandongchae’, and ‘Yudal’ — proved more tolerant than the other two — ‘Youngsan’ and ‘Tammi’. Because rapeseed is in the same family (Brassicacae) as Arabidopsis, one would expect that both share similar genes, with protein coding sequences that show >86% homology. We used a cDNA microarray enriched with Arabidopsis cold stress-related genes to examine the molecular background for differences in sensitivity among rapeseed varieties. Their hierarchical clustering patterns for expression were highly correlated with their cold-sensitive phenotypes. For example, expression patterns were similar between ‘Naehan’ and ‘Sandongchae’ as well as between ‘Yudal’ and our Arabidopsis samples. Using co-expression gene sets developed in this laboratory, we further analyzed expression patterns for three cultivars. Three distinct gene sets were commonly enriched in ‘Naehan’ against ‘Youngsan’ and ‘Tammi’, indicating that they could be the core gene sets that confer a high degree of cold tolerance in ‘Naehan’. Knockout plants with down-regulated expression of GSTF2, TRXh5, LTI30, and LACS4 were highly cold-sensitive whereas overexpression of those four genes led to a reversal of this sensitivity. In fact, overexpression of GSTF2 and LTI30 enhanced tolerance, with plants that over-expressed GSTF2 having extremely high tolerance that enabled them to acclimate almost completely to freezing conditions. By comparison, only about 40% of the wild type demonstrated a similar acclimation. Therefore, the genes described here could be useful in furthering our knowledge about other stress responses in rapeseed, thereby facilitating the production of cold-tolerant plants.     

Evaluation of tomato cultivars to Helicoverpa armigera using two-sex life table parameters in laboratory

Helicoverpa armigera (Hübner) is one of the most important pests of a wide range of agricultural crops worldwide. Resistance of 10 tomato cultivars (‘Primoearly,’ ‘Riogrand,’ ‘CaljN3,’ ‘Kingstone,’ ‘Earlyurbana,’ ‘Petomech,’ ‘EarlyurbanaY,’ ‘Mobil,’ ‘Imprial’ and ‘Petoearly’) to H. armigera was evaluated under laboratory conditions at 25 ± 1 °C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) hours using age-stage, two-sex life table parameters. The larval period ranged from 19.96 on ‘Riogrand’ to 24.58 days on ‘Imprial.’ The insects reared on ‘Imprial’ had the longest total preoviposition period (44.80 days) and those reared on ‘Riogrand’ had the shortest one (35.44 days). The longest adult longevity for female and male was observed on ‘EarlyurbanaY’ (14.40 days) and ‘Kingstone’ (15.00 days), respectively. Using age-stage, two-sex life table, the value of the net reproductive rate (R₀) varied from 7.8 on ‘Imprial’ to 186.9 offspring per individual on ‘Petomech.’ The lowest value of the intrinsic rate of increase (r) and finite rate of increase (λ) was on ‘Imprial’ (0.0410 and 1.0423 day^− 1, respectively) and the highest was on ‘Petomech’ (0.1274 and 1.1359 day^− 1, respectively). The mean generation time (T) on different cultivars varied from 39.9 to 48.2 days. The results revealed that ‘Petomech’ was the most susceptible (suitable) and ‘Imprial’ was the most resistant (unsuitable) cultivar to this pest among the tomato cultivars tested.     

Eucannabinolide and other constituents of Schkuhria virgata

Isolation of eucannabinolide, its 3-isovaleroyl analog and pectolinarigenin from Schkuhria virgata (La Llave et Lex.) DC. is reported. The identity of eucannabinolide, which exhibits in vivo antileukemic activity, with ‘hiyodorilactone A’, ‘20-hydroxychromolaenide’ and ‘schkuhrin I’ is discussed.     

‘Endong’, a rare variety of the farmed carrageenophyte Eucheuma denticulatum (Burman) Collins & Hervey from the Philippines

The variety described in this paper is rather a rare and interesting one. Locally called ‘endong’, this was discovered first in a farm in Tawi-Tawi, Sulu Archipelago, Philippines. During harvest, seaweed farmers used to mix this with ‘tambalang’ (Kappaphycus alvarezii (Doty) Doty ex Silva var. tambalang Doty, the ‘cottonii’ of commerce) because of the presumption of it producing the same carrageenan type as that of ‘tambalang’, viz., kappa-carrageenan. The two farmed varieties are similar in appearance. Complaints arose from seaweed processing plants when the resulting gelling properties (hard and brittle gel) expected of the kappa-carrageenan-producing ‘tambalang’ were not met. Because of its lax habit and long, smooth, and naked basal axes, ‘endong’ was initially thought to be related to ‘tambalang’ and differ from the farmed ‘spinosum’ (Eucheuma denticulatum (Burman) Collins & Hervey) whose typical or common form has shorter axes covered from base to apex with spinous determinate (ramuli) or indeterminate branchlets arranged irregularly and in whorls at predictable interval. However, a closer look at ‘endong’ shows that it also has spinous branchlets arranged in whorls, but confined to the apical portion of the branches. Moreover, its internal axial anatomy shows rhizoidal filaments forming a core. Both characters fit well the distinguishing taxonomic criteria established for E. denticulatum. Chemical characterization of its carrageenan and the determination of its phylogenetic affinities support our morphological findings. Hence, we report and describe ‘endong’ as a rare variety, and we name it E. denticulatum (Burman) Collins & Hervey var. endong Trono & Ganzon-Fortes var. nov. Tips to distinguish ‘endong’ from ‘tambalang’ are included in this paper to aid seaweed farmers in separating the two during harvest.     

Content of different groups of phenolic compounds in microshoots of Juglans regia cultivars and studies on antioxidant activity

Phenolic and other compounds were extracted from micropropagated axillary shoots (microshoots) of the walnut (Juglans regia L.) cultivars ‘Chandler’, ‘Howard’, ‘Kerman’, ‘Sunland’, and ‘Z₆₃’. Among cultivars, microshoots showed differences in phenolic compounds, phenolic acids, flavonoids, and proanthocyanidins. All cultivars contained the phenolics acids chlorogenic acid, gallic acid, p-coumaric acid; the naphthoquinone juglone; and the flavonoid quercetin. The phenolic acids syringic acid and vanillin were present only in microshoots of ‘Howard’. Microshoot extracts had different antioxidant activity with ‘Kerman’ the highest and ‘Chandler’ the lowest in each of three antioxidant assays: the phosphomolybdenum assay (PPM), reducing power assay, and 2,2-diphenyl-1-picrylhydrazyl-scavenging effect. There was a strong linear relationship between total phenolic compound content of microshoots and increasing antioxidant activity.     

Effects of arbuscular mycorrhizal inoculation on the growth,zinc distribution and photosynthesis of two citrus cultivars grown in low-zinc soil

Key message

‘Newhall’ and ‘Ponkan’ citrus cultivars grafted on trifoliate orange with mycorrhization by Glomus intraradices displayed different responses to low-Zn, and the optimal growth of ‘Newhall’ was more fungal inoculation dependent.

Abstract

The effects of arbuscular mycorrhizal (AM) fungus, Glomus intraradices, on plant growth, zinc (Zn) concentration and distribution, and photosynthesis were investigated in ‘Newhall’ navel orange (Citrus Sinensis) and ‘Ponkan’ tangerine (Citrus reticulata) grafted on the rootstock trifoliate orange (Poncirus trifoliata) exposed to low-Zn soil. Under the Zn-poor condition, the two cultivars showed similar decreases in growth, levels of leaf chlorophyll, gas exchange parameters, root soluble sugar, and Zn levels in various plant parts; however, the Zn percentage in the roots of ‘Ponkan’ was increased while in ‘Newhall’ it remained stable, indicating ‘Newhall’ may have a higher Zn translocation efficiency from the roots to the scion’s shoots. AM inoculation improved growth, Zn concentrations and photosynthesis in the two cultivars. AM-infected seedlings had lower minimal fluorescence values but higher maximal fluorescence values than non-infected seedlings. In addition, they were more efficient in terms of photosystem II’s (PS II’s) maximal and potential photochemistry. The greater changes appeared in ‘Newhall’, implying AM symbioses could alleviate the negative effects of low-Zn on the PS II reaction center. In addition, AM-infected ‘Newhall’ and ‘Ponkan’ seedlings had higher Zn percentages in the leaves but lower Zn ratios in the roots than non-AM-infected seedlings, especially in the former cultivar. These results indicate that G. intraradices has the potential to enhance the growth and Zn distribution in ‘Newhall’ grafted on trifoliate orange seedlings grown in low-Zn soil in a greenhouse.     

Differential gene expression analysis of ‘Granny Smith’ apple (Malus domestica Borkh.) during fruit skin coloration

‘Granny Smith’ apples growing under normal sunlight develop green skin, whereas the peel turns red due to anthocyanin accumulation after the removal of a bagging treatment. Two anthocyanins, Cyanidin 3-O-galactoside (cy3-gal) and Cyanidin 3-O-arabinoside (cy3-ara), were detected in the red ‘Granny Smith’ apple peels, and cy3-gal was determined to be chiefly responsible for the red color. The content of cy3-gal was more than 98% of the total anthocyanin in the red ‘Granny Smith’ peels. To better understand the molecular basis of anthocyanin biosynthesis in ‘Granny Smith’ apples, we performed a quantitative real-time PCR (qRT-PCR) analysis of anthocyanin biosynthetic genes (MdCHS, MdF3H, MdDFR, MdANS, MdUFGT, and MdMYB1). Our results indicate that the expression of these genes (except MdCHS) was associated with increased anthocyanin accumulation in the skin of ‘Granny Smith’ apples. Four selected genes obtained from the ‘Granny Smith’ skin cDNA library, phytoene synthase (PSY), WD40 repeat protein, polygalacturonase (PG), and galactosidase (GAL), were also confirmed by qRT-PCR. We found that these genes were differently expressed during ‘Granny Smith’ apple skin coloration, suggesting that they are directly or indirectly involved in pigment accumulation. In conclusion, anthocyanin biosynthesis in ‘Granny Smith’ apples is the result of interactions between multiple enzymes in the anthocyanin biosynthesis pathway, and the coloring mechanism of ‘Granny Smith’ apples may be similar to that of red-skinned cultivars.     

Growth, gas exchange, and water-use efficiency response of two young apple cultivars to drought stress in two scion-one rootstock grafting system

The combination of two scion-one rootstock was used for two apple cultivars, ‘Pink Lady’ and ‘Qinguan’, budded on the same, one-year-old Malus hupehensis (Pamp.) Rehd. to reduce the impact of root and pot size and in order to understand the growth, water-use efficiency (WUE), and chlorophyll fluorescence characteristics. The two-scion grafted trees were planted in plastic pots under two water regimes, i.e. 70% field capacity (FC) and 55% FC. Results indicated that different scions were affected differently by drought stress. ‘Pink Lady’ had higher net photosynthetic rate (P _N), stomatal conductance (g _s), and transpiration rate (E) compared with ‘Qinguan’ under both water treatments. However, ‘Qinguan’ had lower minimal fluorescence (F₀), higher maximum fluorescence (F_m), and higher maximum photochemical efficiency of photosystem II (F_v/F_m) than ‘Pink Lady’ at 55% FC. Moreover, ‘Qinguan’ had larger shoot dry mass (ShDM) and higher intrinsic WUE_I than ‘Pink Lady’ under both water status. Gas-exchange and growth parameters, except for P _N and scion diameter, were significantly affected by the cultivar and water treatment. At 70% FC, ShDM was significantly correlated with WUE_I. Moreover, WUE_I was negatively linearly correlated with g _s at either 70 or 55% FC. These results might indicate that ‘Pink Lady’ was more sensitive to drought than ‘Qinguan’. ‘Qinguan’ apple was able to improve WUE more than ‘Pink Lady’ under both well-watered and drought conditions. The growth parameters and photosynthetic capacity of two different scions showed that the combination of double scion-one rootstock might eliminate the influences of the rootstock and pot size.     

Characterization of self-compatibility in sweet cherry varieties by crossing experiments and molecular genetic analysis

Self-compatibility is a major breeding objective in sweet cherry. The identification and characterization of new sources of self-compatibility will be useful for breeding and research purposes. In this work, self-compatibility of four local Spanish sweet cherry varieties was investigated by crossing experiments and molecular genetic analysis of two self-incompatibility loci. Crossing experiments included self- and cross-pollinations in the laboratory followed by microscopic observation of pollen tube growth and fruit set assay in the field. After crossing experiments, two accessions, ‘Son Miró’ and ‘Talegal Ahín’, were self-compatible while the other two were self-incompatible. Inheritance of S-locus and microsatellite EMPaS02 (linked to self-compatibility, Sc) were investigated in self-pollination progeny of both self-compatible genotypes. Results indicate that self-compatibility in ‘Talegal Ahín’ is similar to self-compatibility described in sweet cherry ‘Cristobalina’ and may be caused by the same mutation. That is a pollen part mutation not linked to the S-locus but linked to microsatellite EMPaS02 in cherry LG3. In ‘Son Miró’ self-compatibility seems more complex, affecting pollen and style function, and probably involving more than one mutation not described previously in sweet cherry. Together with ‘Cristobalina’, the newly described self-compatible varieties ‘Son Miró’ and ‘Talegal Ahín’ confirm the existence of unique self-compatible plant material in local germplasm from Spain that should be conserved and characterized for its use in breeding and research.