Cellulase Activity, Endogenous Abscisic Acid, and Ethylene in Four Citrus Cultivars during Maturation

At maturity, the fruit of two early maturing orange cultivars, Hamlin and Pineapple (Citrus sinensis [L.] Osbeck), contained more ethylene and abscisic acid than the late maturing Valencia and Lamb Summer (C. sinensis [L.] Osbeck) cultivars. Ethylene (up to 95 nl/l in internal atmosphere) and abscisic (50 μg/kg dry weight flavedo) increased most rapidly in Pineapple, leading to increased cellulase activity and loosening of the fruit. Fruit of the two late maturing cultivars contained less than 25 nl/1 ethylene and 40 μg abscisic acid/kg dry weight of flavedo at peak maturity. Cellulase activity and loosening of the fruit of these late maturing cultivars was slight.     

Response of Resistant and Susceptible Bell Pepper (Capsicum annuum) to a Southern California Meloidogyne incognita Population from a Commercial Bell Pepper Field

To determine the presence and level of root-knot nematode (Meloidogyne spp.) infestation in Southern California bell pepper (Capsicum annuum) fields, soil and root samples were collected in April and May 2012 and analyzed for the presence of root-knot nematodes. The earlier samples were virtually free of root-knot nematodes, but the later samples all contained, sometimes very high numbers, of root-knot nematodes. Nematodes were all identified as M. incognita. A nematode population from one of these fields was multiplied in a greenhouse and used as inoculum for two repeated pot experiments with three susceptible and two resistant bell pepper varieties. Fruit yields of the resistant peppers were not affected by the nematodes, whereas yields of two of the three susceptible pepper cultivars decreased as a result of nematode inoculation. Nematode-induced root galling and nematode multiplication was low but different between the two resistant cultivars. Root galling and nematode reproduction was much higher on the three susceptible cultivars. One of these susceptible cultivars exhibited tolerance, as yields were not affected by the nematodes, but nematode multiplication was high. It is concluded that M. incognita is common in Southern California bell pepper production, and that resistant cultivars may provide a useful tool in a nonchemical management strategy.     

Identification of hot pepper cultivars containing low Cd levels after growing on contaminated soil: uptake and redistribution to the edible plant parts

Aims

This study aimed to screen and identify low-cadmium (Cd) hot pepper (Capsicum annuum L.) cultivars and to clarify the mechanisms of low Cd accumulation in fruits.

Methods

A pot experiment was conducted to investigate the variations of fruit Cd concentration among 30 hot pepper cultivars and to determine the differences in uptake and translocation of Cd between low- and high-Cd cultivars in the control and two Cd treatments.

Results

There are significant differences among the cultivars in their ability to accumulate Cd in fruits. Fruit Cd concentrations are positively and significantly correlated with the translocation of Cd from roots to aboveground parts and the Cd concentrations of leaves and stems. However, no correlation was observed between the fruit’s Cd concentration and the root’s Cd uptake ability.

Conclusions

Two hot pepper cultivars, Yeshengchaotianjiao (No. 16) and Heilameixiaojianjiao (No. 23), were identified as low-Cd cultivars, and two, Jinfuzaohuangjiao (No. 13) and Shuduhong (No. 18), were treated as high-Cd cultivars. The difference in fruit Cd concentrations between low- and high-Cd cultivars is attributable to the difference in Cd translocation from roots to aboveground parts and from leaves and stems to fruits, rather than to the root’s Cd uptake ability.     

Identification of anthocyanins in the fruits of Kadsura coccinea using UPLC-MS/MS-based metabolomics

Fruit color is thought to be an adaptation to different animal pollinators, the fruits of Kadsura coccinea present diverse colors but the metabolic mechanism of the differences in color still needs further clarification. Here, we performed ultra-performance liquid chromatography-tandem mass spectrometry based on targeted metabolome analysis of the fruits of two K. coccinea cultivars, ‘Dahong No. 1’ (red-peel) and ‘Jinhu’ (yellow-peel). A total of seventeen anthocyanins were identified in the fruit peels of ‘Dahong No. 1’, whereas no anthocyanins were detected in ‘Jinhu’. Our results suggest that the color differences between the two cultivars can be explained by variations in abundance of cyanidin 3-O-rutinoside, cyanidin 3-O-glucoside and delphinidin 3-O-glucoside, accounting for 91.64% of the content of total anthocyanins. This study provides new insights into the underlying metabolic causes of color variation in K. coccinea fruits, and thus provides a theoretical basis for the development and utilization of K. coccinea fruits in the future.     

Genetic differences in fruit-set patterns are determined by differences in fruit sink strength and a source : sink threshold for fruit set

Background and Aims

Fruit set in indeterminate plant species largely depends on the balance between source and sink strength. Plants of these species show fluctuations in fruit set during the growing season. It was tested whether differences in fruit sink strength among the cultivars explained the differences in fruit-set patterns.

Methods

Capsicum was chosen as a model plant. Six cultivars with differences in fruit set, fruit size and plant growth were evaluated in a greenhouse experiment. Fruit-set patterns, generative and vegetative sink strength, source strength and the source : sink ratio at fruit set were determined. Sink strength was quantified as potential growth rate. Fruit set was related to total fruit sink strength and the source : sink ratio. The effect of differences observed in above-mentioned parameters on fruit-set patterns was examined using a simple simulation model.

Key Results

Sink strengths of individual fruits differed greatly among cultivars. Week-to-week fruit set in large-fruited cultivars fluctuated due to large fluctuations in total fruit sink strength, but in small-fruited cultivars, total fruit sink strength and fruit set were relatively constant. Large variations in week-to-week fruit set were correlated with a low fruit-set percentage. The source : sink threshold for fruit set was higher in large-fruited cultivars. Simulations showed that within the range of parameter values found in the experiment, fruit sink strength and source : sink threshold for fruit set had the largest impact on fruit set: an increase in these parameters decreased the average percentage fruit set and increased variation in weekly fruit set. Both were needed to explain the fruit-set patterns observed. The differences observed in the other parameters (e.g. source strength) had a lower effect on fruit set.

Conclusions

Both individual fruit sink strength and the source : sink threshold for fruit set were needed to explain the differences observed between fruit-set patterns of the six cultivars.     

Flowering, Pollen Grain Germination, Fruiting, Seed Germination and Seedling Development of White Yam, Dioscorea rotundata Poir

The morphology of flowering of several cultivars of Dioscorearotundata, Poir is described. Unisexuality and dioecism occurcommonly although complete flowers have been observed occasionally.The pollen grains are sticky and cannot be dispersed by wind;small insects are probably the main agents of pollination. Pollengrain viability appears to be low. Fruit and seed set are alsovery low and usually not more than five viable seeds are producedon one plant. Production of hybrid plants is feasible if filledseeds are selected and germinated following the end of seeddormancy. Seedling development is described from seed germinationto the establishment of several leaves on the seedling.     

Cryopreservation of fruit germplasm

Most temperate fruit species are genetically heterozygous and vegetatively propagated. Active collections of fruit genetic resources in Germany are generally maintained in the field, e.g., as potted plants for Fragaria and as trees for pome and stone fruit species. The plant material in active collections should be kept in duplicate to ensure security in case of disease or environmental disaster. The aim of this study was to develop an efficient complementary conservation strategy for fruit genetic resources. Although costly, fruit tree cultivars can be duplicated as field collections at a second site within the framework of the German Fruit Genebank, which is a decentralized fruit-specific network. Wild species accessions, particularly those of the genera Malus spp. (apple) and Fragaria spp. (strawberry) as well as strawberry cultivars, can also be duplicated by means of cryopreservation. In the current study, long-term cryopreservation was initiated for 194 Fragaria genotypes. A protocol combining vitrification with cold acclimation was effective and highly reproducible, with an average regrowth rate of 86%. In Malus, a general cryopreservation protocol based on dormant winter buds was adopted. Based on the results provided in this study, a combination of traditional ex situ conservation and cryopreservation can greatly improve the stability and security of fruit germplasm conservation.     

Τhe Role of a Gibberellin 20-Oxidase Gene in Fruit Development in Pepper (Capsicum annuum)

Fruit shape is a very important fruit quality character frequently affected by grafting in vegetable plants like pepper. It has already been shown that, similar to tomato, fruit shape in pepper is likely controlled by an Ovate-like gene, CaOvate, the down-regulation of which positively affects fruit elongation. To further understand the molecular mechanisms involved in pepper fruit shape control and the changes imposed by grafting, we have amplified, sequenced, and structurally characterized CaGA20ox1, the target gene of CaOvate, from a long fruit and a round fruit shaped cultivar. The results show that CaGA20ox1 has similar genomic organization to the tomato GA20ox1 and encodes a 375-amino acid polypeptide that shares 89% identity with tomato GA20ox1. We then studied CaGA20ox1 expression in different pepper plant parts and in different developmental stages of flower and fruit development. The expression of the gene was quantified by means of relative quantitative PCR in the developmental stage of 10?days after anthesis fruit of both cultivars. The results showed that there is a significant difference in the expression of the CaGA20ox1 between the two cultivars in this specific stage as well as in the expression of CaGA20ox1 after virus-induced gene silencing (VIGS) of CaOvate. Finally, the 5?? upstream sequences of CaGA20ox1 gene of the two cultivars were examined and compared. These results corroborate our previous findings, where VIGS of CaOvate alters CaGA20ox1 expression, leading to more elongated fruit, and also progress further the understanding of the genes involved in fruit shape control in pepper opening the way for understanding the molecular means of grafting effects.     

Observations on the fruits and seeds of neotropical Lecythidaceae

Fruit characteristics, embryo types, and funicle-aril features are described for the genera of neotropical Lecythidaceae. Their bearing on the taxonomy of the family is discussed and a generic key based on fruit and seed features is provided. The anomalous seed structure ofAsteranthos brasiliensis is pointed out. Known fruit and seed adaptations for dispersal are described.     

The “sapucaia” group of Lecythis (Lecythidaceae)

Four previously much confused species of Lecythis, which form a coherent group of species collectively known in Brazil as “sapucaias,” are described and differentiated in a key. A summary of their pollination and dispersal is presented as well as of their present-day distributions in relation to past geological and climatological events. Fruit variability, the cause of name proliferation in this group, is described and related to the problem of species concepts in the Lecythidaceae.     

First record of Peridroma saucia Hübner (Lepidoptera: Noctuidae) in transgenic soybeans

The widespread cultivation of transgenic soybeans has caused significant changes in the spectrum of Lepidoptera larvae, both in the number of species as well as on their densities in the field. Transgenic crops producing Bacillus thuringiensis (Bt) insecticidal proteins have successfully reduced the incidence of the most common caterpillars infesting soybeans, namely Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae). However, lepidopteran species not previously recorded on the crop have been recently found, and are of concern due to the possibility of adaptation to the genetically modified cultivars. The occurrence of Peridroma saucia Hübner (Lepidoptera: Noctuidae) is described for the first time in Brazil feeding on genetically modified soybean cultivars.     

DNA marker-assisted evaluation of fruit firmness at harvest and post-harvest fruit softening in a diverse apple germplasm

Several different genes have been proposed as responsible for fruit texture variability at harvest and/or after storage. We have analysed 127 apple cultivars for allelic composition in two key genes that are directly involved in the ethylene biosynthesis pathway, Md-ACS1 and Md-ACO1, and two other genes that are involved in cell wall degradation, Md-Exp7 and Md-PG1. Firmness was measured with a penetrometer at harvest and after 6 or 12 weeks (early- and late-maturing cultivars, respectively) of cold storage. Maturation time was positively correlated with firmness at harvest and negatively correlated with fruit softening rate (difference between firmness at harvest and after storage, divided by number of weeks in storage). Polyploid cultivars showed significantly higher firmness at harvest compared to diploids. Alleles previously described as responsible for good texture were associated with significantly lower softening for Md-ACS1 and Md-PG1, but the opposite was noted for Md-EXP7. Results were nonsignificant for Md-ACO1. Allele frequencies were very uneven in all four loci, with the three most common multi-locus configurations accounting for 64 % of the entire material. The predictive power of these genes was calculated with a partial least squares discriminant analysis, and these accounted for 15 % of the observed variation in initial firmness and 18 % for softening rate. Inclusion of maturation time, storage time (i.e. 6 or 12 weeks) and initial firmness into the model however increased the predictability of softening rate to 38 %. Dividing the material in modern (released after 1960) and old cultivars did not change the outcome of our analyses.     

Induced polyploidy dramatically increases the size and alters the shape of fruit in Actinidia chinensis

Background and Aims

Some otherwise promising selections of Actinidia chinensis (kiwifruit) have fruit that are too small for successful commercialization. We have therefore made the first detailed study in diploid kiwifruit of the effects of chromosome doubling induced by colchicine on fruit size, shape and crop loading.

Methods

Flow cytometric analysis of young leaves and chromosome analysis of flower buds and root tips was used to confirm the stability of induced autotetraploids. Fruit weight, size and crop load were measured in the third year after planting in the field and for three consecutive years. DNA fingerprinting was used to confirm the origin of the material.

Key Results

There was a very significant increase in fruit size in induced autotetraploids of different genotypes of A. chinensis. With the commercially important diploid cultivar ‘Hort16A’, most regenerants, Type A plants, had fruit which were much the same shape as fruit of the diploid but, at the same fruit load, were much larger and heavier. Some regenerants, Type B plants, produced fruit similar to ‘fasciated’ fruit. Fruit of the autotetraploids induced from three female red-fleshed A. chinensis selections were also 50–60 % larger than fruit of their diploid progenitors. The main increase in fruit dimensions was in their diameters. These improved fruit characteristics were stable over several seasons.

Conclusions

Chromosome doubling has been shown to increase significantly fruit size in autotetraploid A. chinensis, highlighting the considerable potential of this technique to produce new cultivars with fruit of adequate size. Other variants with differently shaped fruit were also produced but the genetic basis of this variation remains to be elucidated. Autoploids of other Actinidia species with commercial potential may also show improved fruit characteristics, opening up many new possibilities for commercial development.     

Origin of Chrysanthemum cultivars — Evidence from nuclear low-copy LFY gene sequences

The chrysanthemums (Chrysanthemum × morifolium Ramat.) are a well-known group of traditional ornamental flowers in China and have been cultivated all over the world. Yet the origin of chrysanthemum cultivars has been highly debated. In this study we employ the nuclear low-copy LFY gene to study the evolutionary history of chrysanthemum cultivars. The structure of the LFY gene in all Chrysanthemum species examined is highly conserved with three exons and two introns. The length of the LFY gene in Chrysanthemum varied from 2, 887 to 3, 348 bp. The two introns exhibited high levels of variation in length and sequence composition at the intraspecific and interspecific levels. Phylogenetic analysis of the whole LFY sequences of Chrysanthemum resulted in topologies that contained three major clades. The LFY sequences from the same cultivars are present in two or three clades, supporting that hybridization and allopolyploidy were important mechanisms in the origins of different chrysanthemums. Our results suggest that different cultivars had different ancestors. Chrysanthemum indicum, C. zawadskii and C. nankingense were likely the direct ancestors of most chrysanthemum cultivars examined. Chrysanthemum vestitum is a putative ancestor for some cultivars, and may have indirectly involved in the development of the chrysanthemum cultivars. Sequences of the LFY gene are informative to shed insights into the origin of chrysanthemum cultivars and show great potential as a phylogenetic marker to decipher the phylogeny of Chrysanthemum and its close relatives.     

Ribosomal FISH mapping reveals hybridity in phytoestrogen producing Curcuma species from Thailand

Species in the genus Curcuma (Zingiberaceae) that are cultivated widely in Thailand for their phytoestrogen-producing rhizomes are called wan-chak-motluk. Five cultivars belonging to Curcuma comosa (cultivars with 2n?=?42 and 63) and Curcuma elata (2n?=?63) were examined using the molecular cytogenetic method of fluorescence in situ hybridisation (FISH) in order to identify genetic relationships among these cultivars based on chromosomal maps of the 18S?C25S ribosomal loci. The results revealed hybrid features in this Curcuma species group and a significant similarity among wan-chak-motluk cultivars. The main features included: (1) the presence of the single largest ribosomal site, assigned the Cc1 marker site, in the somatic 2n complement of all cultivars, and (2) the odd numbers of ribosomal sites in the complements, most often in sets of three. We therefore propose that the cultivar with 2n?=?42 (C. comosa) is a homoploid hybrid species comprised of two different ancestral genomes and has a diploid status with the basic chromosome number x?=?21. The cultivars with 2n?=?63 (C. comosa and C. elata) are most probably triploids arising within the 2n?=?42 diploid species/cultivars via a meiotic modification, rather than from hybridisation between diploid and tetraploid plants. The knowledge about genetic and genomic relationships among wan-chak-motluk cultivars will be important in the research projects that aim to explore and promote new plant materials for cultivation.     

Development of <Emphasis Type="Italic">Colletotrichum acutatum</Emphasis> on Tolerant and Susceptible <Emphasis Type="Italic">Olea europaea</Emphasis> L. cultivars: A Microscopic Analysis

Colletotrichum acutatum is a cosmopolitan and damaging plant pathogen of temperate, subtropical, and tropical fruits and causes anthracnose on olive (Olea europaea L.). Three olive cultivars showing a variable response to infection by C. acutatum were selected to a preliminary study of pathogen development. Fruit samples, from susceptible and tolerant cultivars, were taken at 0, 24, 48, 72, and 192 h after inoculation for a microscopic and histological study of the infection and colonization process. The aim of this study was to compare the infection process: conidial germination, germ tube and appressorium formation, hyphal growth, and mesocarp colonization in susceptible and tolerant olive cultivars as a condition for further exploration of disease development, which is required to develop cultivars with improved resistance to anthracnose. The rate of mesocarp colonization differed between the susceptible and tolerant cultivars, and both intracellular hemibiotrophy and subcuticular intramural necrotrophy were observed. Hemibiotrophic infection predominated in the moderately tolerant cultivar.