Inter-simple sequence repeat (ISSR)-PCR analysis to assess genetic diversity in a collection of wild cloudberry (Rubus chamaemorus L.) clones

Summary

Forty-eight wild cloudberry (Rubus chamaemorus L.) clones, collected from four Canadian Provinces, were assessed for genetic variability using inter-simple sequence repeat (ISSR)-PCR methods. Nine primers generated 138 polymorphic ISSR bands. A substantial degree of genetic diversity was found among the wild collection. Cluster analysis by the unweighted pair-group method with arithmetic averages (UPGMA) separated the 48 wild clones into six main clusters, and identified the one remaining clone as an outlier. Furthermore, within four of the clusters, the clones tended to form sub-clusters that were in agreement with a principal coordinate (PCO) analysis. Geographical distribution explained 8% of the total variation revealed by analysis of molecular variance (AMOVA). The ISSR markers detected a sufficient degree of polymorphism to differentiate among cloudberry clones, making this technology valuable for germplasm management, and more efficient choices of parents in current cloudberry breeding programmes.     

The frost hardiness of some clones of olive cv. Leccino

Summary

Frost hardiness of four olive clones (Olea europaea L.) belonging to cv. Leccino was studied and compared with that of a susceptible clone of cv. Moraiolo by ionic leakage. Variability of the trait was found within the clones of ‘Leccino’, some of which were statistically different from a the ‘Moraiolo’ clone at one or both temperatures tested. Only one clone showed a significant difference between ?15° and ?20°C. The ionic leakage technique is appropriate for studying changes in physical properties of membranes and its use in the screening of frost tolerant olive clones is discussed.     

Integration of the rolA gene into the genome of the vigorous apple rootstock A2 reduced plant height and shortened internodes

Summary

The aim of this work was to dwarf the vigorous apple rootstock A2 by insertion of the rolA gene. To optimize conditions for a successful transformation, regeneration tests were carried out. The use of sucrose in the regeneration medium gave higher regeneration frequency than sorbitol in some cases and the shoot number per regenerated leaf was higher at 10 |j.M TDZ compared with 2.5 |j.M TDZ on the sucrose medium. Two transgenic clones, verified by PCR and Southern analysis, have been obtained on the sucrose medium together with 2.5 |j.M TDZ and 1.0 or 2.5 |j.M NAA and wounding by forceps. The two clones, named LAI and LA2, contained both the rolA and nptll genes. The results of in vitro rooting showed that LAI had a lower rooting percentage and a reduced root number per rooted shoot than the untransformed control shoots and the clone LA2 on the rooting medium containing 5 |JLM IBA. Growth analysis revealed that both transgenic clones had a reduced plant height and a shortened internode length compared with the control plants. However, the node number and the stem diameter were significantly larger for clone LAI than clone LA2 and the control plants.     

Effect of continuous or intermittent radiation on sweet potato plantlets in vitro

Summary

Single-node cuttings of sweet potato [(Ipomoea batatas (L.) Lam. ‘Beniazuma’)] were cultured in vitro for 35 d under intermittent blue light (IB), intermittent red light (IR) and intermittent blue-plus-red light (IBR) provided by light-emitting diodes (LEDs) flashing for 10 s three-times min^–1. Growth was compared with cuttings cultured under continuous blue (B), red (R) or blue-plus-red (BR) light, or cool-white fluorescent lamps (FL) with a 16 h photoperiod. Dry weights, leaf areas and carbohydrate contents were greater under the IB and IBR treatments than in the FL treatment. Our results show that a novel light source during in vitro culture of sweet potato plantlets may provide an opportunity to improve plant yield in large-scale greenhouses for commercial purposes.     

Observations on the Field Performance of Heat-Treated Strawberry Clones

The growth and cropping of two virus-infected strawberry varieties was compared with that of clones the virus content of which had been reduced by heat therapy.

The heat-treated clones of both Cambridge Favourite and Early Cambridge were considerably more vigorous, bearing more crowns than their untreated counterparts. In the first year after planting, both clones of each variety produced similar total yields, but the heat-treated clones produced a higher percentage of large fruit. Plants of the heat-treated clone of Cambridge Favourite flowered and ripened their fruit later than plants of the untreated clone in the second year, but gave a greater yield. However, the two clones of Early Cambridge gave similar yields, the increased potential of the heat-treated clone provided by a greater number of crowns being offset by reduced inflorescence formation.

In order to establish whether reduction of vigour would lessen the tendency of some heat-treated clones to form barren crowns, spring planting was compared with autumn planting. Spring planting, which reduced plant size and yield of both varieties in the first season but had less effect on size and none on yield in the second season, failed to check partial barrenness in the heat-treated clone of Early Cambridge.

At the end of the first growing season the heat-treated clones of both varieties showed a greater incidence of Verticillium wilt than the untreated clones but this difference was not maintained in the second year.     

A study of the ecological variability in yield of selected clones of Arabica coffee (Coffea arabica L.) from the coffee-breeding programme in Kenya

Summary

Cherry yield of eleven elite clones of Arabica coffee was evaluated over a five-year period at three locations in a continuing study to detenriine the extent and influence of Clone X Environment interactions on coffee breeding lines developed in Kenya. Clone mean yield comparisons indicated a better performance of all the improved clones compared with the Standard. In analysis of variance (ANOVA) significant main effects and non-significant Clone X Environment interactions (P<0.05) were found. Interactions were however, further investigated using ecovalence values, the Eberhart and Russell (1966) regression model as well as the Additive Main effects and Multiplicative Interaction effects (AMMI) model. The clones were then clustered according to their response patterns using principal components and cluster analyses to obtain a delineation of ecological districts and more accurate predictions of clone performance. The main effects for clones reflected breeding advances with the standard variety having the smallest mean. Improved materials from the hybridization scheme appeared to do better than their pure-line counterparts with clones 8,3,1 and 2 being the most advanced of the 11 clones. Similarly, the main effects for the environment reflected the overall site/year quality with Kiambu having the best production conditions particularly due to the favourable weather in 1983. This indicates that the coffee growing upper zone may be favourable for the clones especially when they are raised by top-working old coffee. Makuyu environments had the least interaction effects.     

Growth,yield and essential oil content of three cultivars of basil grown under different levels of nitrogen in the field

A field experiment was conducted in Southern Italy to investigate the effect of different nitrogen (N) rates (0, 100 or 300 kg ha⁻¹) on the number of branchings and leaves per plant, plant height, yield of above-ground fresh biomass, total leaf area, dry weight, leaf-to-stem ratio, leaf essential oil content and the essential oil quality at commercial harvest (full bloom) of the three cultivars of basil (Ocimum basilicum L.): (i) “Mostruoso mammouth” (MM); (ii) “Genovese profumatissimo” (GP); (iii) “Napoletano a foglia di lattuga” (NFL). Nitrogen fertilization up to 300 kg ha⁻¹ increased yield of above-ground and leaf fresh biomass, leaf essential oil yield, but it did not affect leaf-to-stem ratio, plant height and the number of branchings per plant. The increase in essential oil yield induced by N fertilization depended on an increase in both leaf essential oil concentration and leaf biomass. The increase in LAI with increasing N fertilization was due to an increase in leaf number per plant rather than in individual leaf expansion. The cultivar GP was different in morphology from MM and NFL, since it had greater leaf number and plant height, but lower leaf-to-stem ratio and LAI. The physiological efficiency of N use (PE) in producing above-ground biomass was not related to N application whereas PE in producing essential oil (PE-oil) tended to increase with increasing levels of N applied. With regard to the effect of the cultivar, GP was less efficient in N use for oil production than MM and NFL since PE-oil of GP was lower while leaf N and PE-biomass were higher than the other cultivars. NFL was the richest in methyl chavicol but the lowest in linalool, whereas MM and GP contained linalool and eugenol.     

An efficient adventitious shoot regeneration system on excised leaves of micropropagated lingonberry (Vaccinium vitis-idaea L.)

Summary

An efficient system to regenerate shoots in vitro on excised leaves of lingonberry (Vaccinium vitis-idaea L.) was developed. Leaf explants from shoot-proliferating cultures produced multiple shoots without an intermediary callus phase on zeatin (ZN)-containing shoot induction media within 3–4 weeks of culture initiation. Cultivars Regal and Splendor, and one clone from a natural stand in Estonia (ECL1), were used in the first experiment. Young expanding leaves with the adaxial side touching the culture medium, and maintained for 7 d in darkness, produced the best results. There were significant genotypic differences in adventitious shoot formation. A second experiment studied the effects of ten concentrations of three cytokinins: ZN at 5, 10, 20, 30 and 40 μM; 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea (thidiazuron, TDZ) at 0.1, 1, 5 and 10 μm; and 6-(γ-γ-dimethylallylamino) purine (2ip) at 25 μM were compared with leaf segments of different polarity in ‘ECL1’. Zeatin was found to be more effective than TDZ or 2iP as an inductive signal for regenerating many vigorous shoots. Zeatin induced multiple shoot formation at all concentrations tested, but maximum morphogenic response was observed at 20 to 30 μM. The media containing TDZ generally promoted more callus formation and suppresed shoot elongation. In a third experiment with the lingonberry cultivar Erntedank and the clone ‘ECL1’, a new medium developed for lingonberry shoot culture proved more effective than the modified Murashige and Skoog medium for regenerating shoots on leaf explants. Elongated shoots were excised and rooted directly on a 2 peat:1 perlite (v/v) medium after dipping in 0.8% indole-3-butyric acid. Rooted plantlets were acclimatized under greenhouse conditions to evaluate somaclonal variation.     

Flowering Tendencies in Octoploid Strawberry Species

ABSTRACT

The U.S. Department of Agriculture, National Clonal Germplasm Repository (NCGR), Corvallis, Oregon, maintains a national genebank for strawberry, Fragaria L. This collection includes diverse species maintained in screenhouses. The plants are exposed to an annual temperature regime that allows flowering. The objective of this project was to examine the flowering tendencies of octoploid strawberry taxa to determine if the blooms were seasonal (once per year) or successive blooming (remontant). For each of 68 clones of nine taxa, flower presence was recorded on the first day of each month from June through Oct. 2002 and in 2004. Complete flower trusses were removed after scoring. Plants flowering only in June and/or July (or earlier) were considered “seasonal”; those with later flowers were considered “successive blooming.” For both years, North American F. chiloensis ssp. lucida and ssp. pacifica flowered seasonally, significantly different than clones of ssp. chiloensis f. patagonica, half of which were successive blooming. A clone of ssp. pacifica from Hartney Bay, Alaska, was successive blooming. The flowering in two clones of South American ssp. chiloensis f. chiloensis and one of the Hawaiian ssp. sandwicensis were seasonal. Fragaria virginiana ssp. grayana clones and half of the ssp. virginiana Mill. flowered seasonally; the rest of the clones of those subspecies were successive blooming. Flowers of a clone of F. virginiana ssp. platypetala from California were seasonal while those from a second one from Eastern Oregon were successive blooming. This clonal phenotypic information is of specific use for geneticists to determine parental crosses. This study will be continued and broadened to include diverse global species.     

The effect of split-root salinity stress on tomato leaf expansion,fruit yield and quality

Summary

A crop-scale experiment between March and October 2000 investigated the effects of split-root salinity stress and rooting volume on the expansion of leaves, fruit yield and quality in two standard round fruited cultivars of tomato (Lycopersicon esculentumMill) Solairo and Espero, grown in rockwool. To implement the treatments, a split-root method was utilized whereby different levels of salinity (expressed as EC), adjusted by the addition of NaCl, was administered to two halves of a root system. The split-root high EC (2.8/8.0 dS m^–1) treatment enhanced fruit quality by increasing the concentrations of sugar, acid, total soluble solids and reducing the incidence of visual defects such as uneven ripening and gold-spot. Split-root high EC did however reduce leaf area that corresponded with low K concentration in the leaf tissue. The split-root method utilized doubled the rooting volume compared with the standard single rockwool slab, but this extra rooting capacity had no detectable effect on leaf expansion, yield or fruit quality. Although there was little impact on yield for ten weeks after the imposition of the high EC split-root treatment, mean reductions in weekly yield occurred thereafter and were of the order of 9 and 13% for ‘Solairo’ and ‘Espero’ respectively through to the end of the experiment. The fall in yield was due, in part, to a decrease in fruit size. Whilst water uptake was reduced it was unclear how the effects on leaf growth and fruit yield were mediated in the shoot. Possible processes that coordinate responses to root-zone salinity stress are discussed. The potential use of the split-root system in commercial production is considered.     

Sink strength and photosynthetic capacity influence tuber development in sweet potato

Summary

Tuber growth of sweet potato clones is shown to depend on the sink strength of the developing tuber, the potential of leaves to export photoassimilates, but also on the photosynthetic capacity of leaves. Evidence from experiments with the short-lived radioisotope ¹¹C and from growth experiments in the glasshouse is presented in favour of the hypothesis that tuber formation promoted photoassimilate export from fully expanded leaves and also leaf photosynthesis. In the sweet potato clone ‘AB94078.1’, a low photosynthetic capacity could be explained by a limitation of Calvin cycle activity, notably of Rubisco activity. The light reactions of photosynthesis did not limit net photosynthesis in the investigated clones under the non-saturating light conditions during the experiment.     

Field performance and molecular diversification of lemon selections

Lemon (Citrus limon (L.) Burm. f.) is one of the most important Citrus fruit for Turkey because of its great amount of production and export. It has been cultivated for a long time in Turkey, and therefore variations for agronomical traits are likely among cultivated lemons due to bud mutations and, hybridizations. The objectives of this study were to determine variations for some selected agronomical traits and genetic markers among 12 new lemons derived from selections. Tree growth, yield, fruit quality, and molecular diversification of these clones were determined. After four years of evaluation, ‘Kutdiken’ M-51 indicated the highest canopy volume. For yield per tree, the best clone was ‘Kutdiken’ M-51. After five years of evaluation, ‘Kibris’ M-54 had the highest fruit weight and acidity. ‘Italian Memeli’ M-56 contained the lowest seed number and the highest total soluble solids. Molecular analysis, as assessed with 22 random amplification of polymorphic DNA (RAPD) and 11 inter simple sequence repeats (ISSR) primers, indicated that seven of twelve clones were separated with RAPD markers, whereas four were distinguished with ISSR markers. Combined analysis of RAPD and ISSR data detected that similarity values among the lemons clones were between 0.97 and 1.00. It can be concluded that variations in orchards are abundant and mainly due to mutations.     

Cloning,characterisation, and expression analysis of an oleosin gene in coconut (Cocos nucifera L.) pulp

Summary

Oleosins are structural proteins found in oil bodies, organelles found in the cells of plant tissues with a high oil content that undergo extreme desiccation as part of their maturation process. Oleosins stabilise oil bodies. In this paper, a full-length cDNA sequence homologous to oleosin, a seed-storage oil-body protein, from coconut (Cocos nucifera L.) was identified from cDNA libraries during fruit development and characterised. The gene, termed Coco-Ole, contained an open reading frame of 375 bp encoding a polypeptide of 125 amino acids. The predicted amino acid sequence of coconut oleosin had a molecular mass of 13.0 kDa, and showed 92% (AAF76238.1) and 67% (AAC02239.1) sequence similarity to oil palm (Elaeis guineensis Jacq.) and rice (Oryza sativa) oleosin proteins, respectively. The amino acid sequence clustered in the same branch as oil palm in the cladogram, but was distant from other species. The results of semi-quantitative RT-PCR indicated that the Coco-Ole gene was expressed only in the pulp, and its expression increased significantly during pulp development. Compared with fluctuations in oil content, expression of the Coco-Ole gene was consistent with the anabolism of oil during pulp development. The cloning and sequencing of the Coco-ole gene provides a new marker for studies on oil body biogenesis and fruit development in coconut.     

Long-term effect of irrigation with saline water on the development and productivity of jojoba clones

Summary

Three commercial clones of jojoba (Simmondsia chinensis) (64, Q-106 and 879–154) were planted in June 1991 at the Ramat Negev Experimental Station (Israel) and fertigated with water at three salinity levels, 1.2, 3.4 or 6.2 dS m^?1. The effects of salinity over three and a half years on key metabolic activities, on plant growth and development, on flowering characteristics, and on yield were studied. Salinity barely inhibited the rate of net photosynthesis, although it did reduce stomatal conductivity by about 50%. Salinity also affected the water status of the plants by reducing water potential. Growth of the plants was not greatly affected by salinity. It was found that jojoba plants accumulate sodium and chloride ions in their leaves and use a strategy typical of many halophytes to cope with the salinity. The effect of salinity on flower development was also studied, since the vitality of flowers is a key factor in obtaining seeds. Salinity did not affect the timing of the breaking of flower bud dormancy in the 1992-93 season, although it did delay flower bud growth in clones Q-106 and 64. Salinity brought forward the flowering of clone 879–154 by about a fortnight in the 1993-94 season, but did not affect the flowering pattern of the other clones. Fruit set was not inhibited by salinity in the 1994 or 1995 season, and no significant effects were found on yield and wax content in 1994 season, but yield was reduced by salinity in the 1995 season.     

Influence of rootstock on vegetative growth,fruit yield and quality in ‘Cuore di Bue’, an heirloom tomato

Summary

Heirloom tomatoes (Solanum lycopersicum L.) such as ‘Cuore di Bue’ are highly appreciated by consumers for their outstanding quality and flavour. Nowadays, they are often grafted onto vigorous rootstocks in order to overcome several soil-borne diseases. The present study was conducted in 2007 and 2008 in Southern Italy. Plants of ‘Cuore di Bue’, an heirloom ‘oxheart’ tomato, were grown in a greenhouse either as non-grafted plants, or grafted onto two inter-specific (S. lycopersicum S. habrochaites) rootstocks (‘Beaufort F₁’ and ‘Maxifort F₁’) in order to evaluate their effects on vegetative growth, marketable yield, fruit quality, and the sensory properties of ‘Cuore di Bue’ tomato fruit. Growth analysis revealed that ‘Maxifort F₁’ enhanced plant growth, particularly in terms of leaf area and leaf fresh weight. Grafted plants had higher leaf area ratios (by 13%) and higher leaf dry weight fractions (by 18%) compared to non-grafted ‘Cuore di Bue’ plants. Marketable yields increased by 20 – 25% in grafted plants in both years. However, total soluble solids (TSS) contents, titratable acidity (TA), and TSS/TA ratios were not significantly affected by grafting.Vitamin C contents decreased by 14 – 20% in both years in the fruit of plants grafted onto either rootstock. The sensory profiles of fruit were not modified by grafting, although taste panelists expressed a higher preference for purchasing fruit from plants grafted onto ‘Maxifort F₁’. These results confirm that, when using the appropriate rootstock/scion combination, grafting can improve plant growth and the marketable yield of heirloom tomato fruit without reducing the sensory quality of the fruit or its biochemical parameters. However, grafting can reduce vitamin C contents and, thus, nutritional quality.     

Characterization of five sour orange clones through molecular markers and leaf essential oils analysis

Five clones of sour orange (Citrus aurantium L.) showing significant morphological differences were selected from our germplasm collection and characterized both by genetic and leaf volatiles analysis. The genetic studies were undertaken by the use of molecular markers developed by PCR-based techniques (ISSR and RAPD), while the leaf essential oil patterns were obtained by chromatographic and mass spectrometric determination. Data obtained suggest that reasonably similar information can be achieved from the two techniques, supporting each other in characterization studies.     

Effect of humidity and nutrient feed K/Ca ratio on physiological responses and the accumulation of dry matter,Ca and K in tomato

Summary

Two levels of humidity, high, 0.1 kPa vapour pressure deficit (vpd) and control 0.5 kPa vpd, and four nutrient feed K/Ca mM ratios (4/7, 10/7, 4/2 and 10/2) were applied in all factorial combinations to a nine-week old tomato (Lycopersicon esculentum Mill.) crop for 63 d. The effect on gas exchange, water relations, vegetative growth, yield and accumulation of Ca and K in the shoot was examined. High humidity had a deleterious effect on leaf expansion, delayed truss and fruit maturity and reduced fruit yield. Water uptake was reduced and the Ca concentration of leaf and fruit tissue was increased under high humidity compared with plants grown under control humidity; K accumulation was unaffected. The accumulation of K and Ca in the shoot appeared to be poorly related to the rate of transpiration. The high (10/2 mM) K/Ca ratio nutrient feed had little effect on vegetative growth and yield compared with the low (4/7 mM), but restricted Ca uptake to the fruits at both the high and the control humidity. During the measurement period, 0900–1300 hours, stomatal conductance and leaf water status remained high at elevated humidity, compared with a progressive reduction in leaf water status and low stomatal conductance in the control humidity. A/c_i gas exchange analysis where A is the net CO₂ assimilation rate and c_i is the intercellular partial pressure of CO₂ suggested that, at high humidity, the photosynthetic capacity of the leaves was reduced because of a lower in vivo carboxylation efficiency. However, the mechanism(s) responsible for reduced leaf expansion remains unclear. The complex interrelations between physiological responses, leaf expansion and the uptake and distribution of K and Ca to the shoot, are discussed.     

Effects of the application of ‘cash’ on the growth,fruit yield,and nutrient status of tomato (Solanum lycopersicum L.) grown in reclaimed saline soil

Summary

The effects of ‘cash’ [a novel 2:5:1 (w/w/w) mixture of calcium sulphate, ground sunflower heads, and humic acid] as a soil amendment on the growth, fruit yield, and leaf nutrient status of tomato (Solanum lycopersicum L.) grown on reclaimed saline soil (EC = 9.4 dS m^–1) were investigated. A glasshouse experiment was performed in a completely randomised design with six treatments (0, 10, 20, 30, 40, or 50 g ‘cash’ kg^–1 soil) each with four replicates. The results indicated that ‘cash’ increased both the shoot dry weight (DW) plant^–1 and the root DW plant^–1, the free proline contents of leaves, and leaf chlorophyll contents. The use of ‘cash’ also increased the number of fruit plant^–1, fruit yield pot^–1, and fruit vitamin C contents, although total soluble solids (TSS) contents were not affected. The contents of nitrogen (N), potassium (K), and calcium (Ca), and the Ca:Na ratios of leaf tissues increased with all application rates of ‘cash’. Leaf phosphorus (P) contents showed no response to any applied level of ‘cash’. Leaf sodium (Na) contents declined gradually with an increase in the level of ‘cash’ applied to the soil. We concluded that ‘cash’ has a pronounced positive effect on the growth and fruit yield of tomato plants grown in reclaimed saline soil. ‘Cash’ therefore has the potential to be used as a soil amendment for vegetable crops such as tomato to overcome the adverse effects of salinity in newly-reclaimed soils.     

Orange varieties as interstocks increase the salt tolerance of lemon trees

Summary

We investigated the ability of interstocks to increase salt tolerance in lemon trees. We compared 2-year-old ‘Verna’ lemon trees [Citrus limon (L.) Burm.; VL] grafted on Sour Orange (C. aurantium L.; SO) rootstock either without an interstock (VL/SO), or interstocked with ‘Valencia’ orange (C. sinensis Osbeck; VL/V/SO), or with ‘Castellano’ orange (C. sinensis Osbeck; VL/C/SO). Trees were grown under greenhouse conditions and supplied with nutrient solutions containing 0, 30, or 60 mM NaCl. Reductions in leaf growth caused by salt treatment were greatest in non-interstocked (VL/SO) trees, followed by VL/C/SO trees, and were the least in VL/V/SO trees. Although the levels of Cl^? and Na⁺ ions in the roots and stems were not affected by either interstock, leaf concentrations of Cl^? and Na⁺ were higher in VL/SO trees than in VL/C/SO or VL/V/SO trees, suggesting that an interstock in Citrus trees could limit the uptake and transport of such ions to the shoots. Saline-treated VL/SO trees also tended to have the lowest shoot:root (S:R) ratios; so, overall, there was a negative relationship between S:R ratio and leaf Cl- ion concentration. Leaf transpiration (E_leaf) may also be involved in the reduction in leaf Cl^? concentration, as interstocked trees had lower E_leaf values at mid-day than non-interstocked trees. Salinity increased leaf concentrations of Ca²⁺ in VL/C/SO trees and increased both leaf K⁺ and N concentrations in all trees, regardless of interstock. Salinity reduced leaf water potentials and osmotic potentials, such that leaf turgor was increased in all trees.