Identification of ‘Sib’ plants in hybrid cauliflowers using microsatellite markers

Hybrid cauliflowers have been developed to exploit heterosis and to improve uniformity of production. Two breeding systems are commonly employed, self-incompatibility (SI) and cytoplasmic male sterility (CMS). Sibs, assumed to be self-inbred, often contaminate hybrid seed lots in the SI system and whilst self-inbreeding is not possible in the CMS system, plants that look like sibs occur. The objective of this study was to develop microsatellite markers for male and female cauliflower parent lines of both SI and CMS systems and to use them to screen sibs and aberrant plants in F₁ hybrids. Fifty six pairs of microsatellite primers were screened and 8 primer pairs produced co-dominant markers in parent plants and two pairs of markers were chosen for purity testing of F₁ hybrid seeds. Controlled pollinations were conducted in the glasshouse to produce hybrid and selfed-seeds. These seeds were grown in a field trial to identify morphologically normal and sib plants and to assess the reliability of microsatellite markers in detecting sib plants. Microsatellite analysis of morphological sib plants from the SI system revealed that these were not always self-inbred, in contrast, most self-inbred plants showed normal growth. Similarly, all morphological sibs from the CMS system showed hybrid bands. This suggests that morphological sibs were not always due to selfing but possibly to an interaction between genetic and environmental factors and this requires further investigation.     

Comparative genetic analysis of field resistance to downy mildew in the lettuce cultivars ‘Grand Rapids’ and ‘Iceberg’

Downy mildew on lettuce is currently controlled using host resistance genes (Dm genes) that confer race-specific resistance in seedlings. Field resistance (FR) that is active in adult plants but not seedlings was identified in the cvs. Grand Rapids and Iceberg. The goal of our study was to evaluate the utility of Grand Rapids as a source of novel Bremia resistance alleles, particularly in comparison with Iceberg. To measure FR, downy mildew symptoms were evaluated following natural infection in field experiments. The responses of Grand Rapids and Iceberg were similar in many respects. Although both cultivars had a small percentage of plants exhibiting disease symptoms, the average disease ratings were as low as for cultivars with effective Dm genes. We observed no evidence for race specificity. FR was effective over 3 years of our study, despite documented variation within pathogen populations. Both cultivars lacked all known seedling resistance genes except Dm13, which was not responsible for the resistance observed in field experiments. Similar segregation of FR was observed in F₂ populations for both Grand Rapids and Iceberg. The presence of highly susceptible families within Grand Rapids × Iceberg populations suggested the presence of at least one unique resistance allele in each cultivar. Preliminary genetic analysis of FR from Grand Rapids revealed a high estimate of narrow-sense heritability that suggested simple inheritance, but single gene models did not fit the observed data. Our results suggest that Grand Rapids may represent an underutilized resource for controlling downy mildew in lettuce.     

Correlation and path-coefficient analyses of ripening attributes and storage disorders in ‘Ambrosia’ and ‘Empire’ apples

The objectives of this study were: (1) to determine correlation effects among the ripening attributes of ‘Empire’ and ‘Ambrosia’ apples during storage, and (2) to determine the direct and indirect contributions of these ripening attributes on the incidence of physiological disorders and storage rots using path-coefficient analysis. The analysis was applied to data obtained from a variety of harvest dates and storage regimes from apples. Pearson correlation analysis of the data indicated a strong positive correlation between internal ethylene concentration (IEC) and peel greasiness, a negative correlation between IEC and soluble solids concentration, and a negative correlation between firmness and peel greasiness in both cultivars, as well as a negative correlation between IEC and firmness in ‘Empire’. Results indicated that increased IEC in ‘Ambrosia’ apples during storage was related to higher incidences of core browning and lenticel damage and lower incidence of internal browning. Higher IEC in ‘Empire’ apples during storage was associated with less internal browning. Several significant correlations, representing different relationships among the ripening attributes and storage disorders were obtained.     

Differential meiotic behaviour in hybrid clones of Aranda ‘Christine’ (Orchidaceae)

Summary The hybrid orchid clones of Aranda Christine show differential meiotic behaviour with respect to meiotic irregularities in the form of non-congressing chromosomes, laggards and complement fractionation. These irregularities occur in significantly variable but high frequencies, which results in the observed sterility of these hybrids. The observed differential meiotic behaviour is probably due to the transmission of a variable set of chromosomes from the third generation hybrid parent, Vanda Hilo Blue. Deviant spores, mainly polysporous and polyploid, are the end products of the meiotic aberrations. Such spores appear to be produced regularly in the intergeneric orchid hybrids.Meiosis in one of the Aranda Christine clones, C80, was found to be highly aberrant and could be unique among orchid hybrids.     

Comparative analysis of petal proteins in red and white lines from near-isogenic Portulaca sp. ‘Jewel’ plants

Summary A couple of near-isogenic lines, JR and JW from Portulaca sp. Jewel has red and white petals respectively. The difference in petal color in the two lines is caused by an alteration of single genetic locus which is involved in the biosynthesis of betalain pigmentation. In order to detect this genetic difference at the polypeptide level, we have now attempted the comparative analysis of petal proteins between JR and JW. The protein profiles of SDS-polyacrylamid gel electrophoresis from three different stages of the developing petals, and the autoradiographic protein profiles of in vivo labeled petals howed that a 27 KD fragment strongly appeared as a characteristic of JR petal fraction. Thus, this fragment can be considered as a candidate for certain polypeptides which is associated with the betalain synthesis pathway functioning in the pigmented petals.Abbreviations SDS sodium-dodecyl sulfate - KD kilo-dalton - DOPA 3,4-dihydroxyphenylalanine     

Partial self-compatibility in ‘Tombul’ and ‘Montebello’ hazelnuts

Summary Self-pollination of hazelnut (Corylus avellana L.) cultivars in 1988 and 1990 revealed the existence of partial self-compatibility in Tombul and Montebello. Percent cluster set in these cultivars averaged 44 and 20%, respectively, but was less than 10% in 8 other cultivars investigated. Percent cluster set from pollination with Segorbe averaged 62 and 41% in 1988 and 1990, respectively. Self-pollination produced 40% fewer nuts per cluster and twice as many blanks as cross-pollination. All cultivars and selections have an active sporophytic incompatibility system.Evaluation of self-compatibility in seedlings from the cross Montebello × Compton revealed that the partial self-compatibility of the maternal parent was transmitted to some of the progeny. Self-pollination resulted in greater than 10% cluster set in two selections, OSU 41.134 and OSU 43.025, in both years, but only in 1988 in OSU 42.089 and Willamette. Three other selections had very low set in both years. Results of incompatible crosses with standard testers were generally in agreement with those of self-pollination, except that the S₂ tester induced greater set on 3 genotypes in 1988 and the S1 tester on 2 genotypes in 1990 than self-pollination. The partial self-compatibility of Montebello, OSU 41.134, and OSU 43.025 appears to be due to a failure of their stigmas to prohibit pollen tube growth in incompatible crosses. There is no evidence of a pollen-part mutation in Montebello, nor is there evidence that partial self-compatibility is due to the interaction of S-alleles, as Barcelona, which has the same alleles as these three genotypes, failed to set nuts in all incompatible crosses.     

Use of hot water treatment to control codling moths in harvested California ‘Bing’ sweet cherries

Preharvest gibberellic acid-treated California ‘Bing’ sweet cherries (Prunus avium L.) were treated with hot water baths (46–58 °C for 0.25–18 min), followed by hydrocooling. The fruit were then stored to simulate either air shipment or sea shipment to overseas markets, both followed by 15 h of shelf life at 20 °C. In separate experiments, cherries were also infested with codling moth larvae and subjected to similar hot water bath heating. The quality attributes showed different sensitivity to the combinations of temperature and time used for hot water bath treatment. Pitting was more common in fruit treated at lower temperatures for longer times, while stem browning was more common in fruit treated at high temperatures. Berry browning, stem color, and pitting were the quality attributes most affected by heat treatment. Browning of cherry stem color was a crucial factor in determining whether a combination of temperature and time for hot water bath treatment was successful. All cherries stored at 0 °C for 14 days to simulate sea shipment were of unacceptable quality after shelf life. Hot water bath treatments that provided 100% codling moth mortality and maintained overall acceptable fruit quality were very limited and included treatments at 50 °C for 10 min and at 54 °C for 6 min. Delaying the hot water bath treatment after fruit harvest, even if the cherries were kept at 0 °C, resulted in a greater loss in fruit quality compared with those treated on the harvest day. Using hot water baths as a quarantine treatment for codling moths (Cydia pomonella) on sweet cherries may be feasible if fruit are air shipped at 5 °C for 2 days, but not suitable if fruit are sea shipped at 0 °C for 14 days.     

Integrated ethylene and temperature conditioning for induction of ripening capacity in ‘Anjou’ and ‘Comice’ pears

‘Anjou’ and ‘Comice’ pears from three harvest dates were conditioned to develop ripening capacity by exposure to 100 μL L⁻¹ ethylene at 20 °C for 0, 24, 48, or 72 h, followed by varying durations of temperature conditioning at −0.5 or 10 °C. Ripening capacity was tested by measuring fruit firmness after 7 d at 20 °C after completion of conditioning treatments. Fruit firmness was also measured after conditioning but before ripening, and was designated “shipping firmness”, indicative of the potential for the fruit to withstand transport conditions without physical injury. Ripening capacity in both cultivars developed more rapidly with later harvest date, increasing duration of ethylene conditioning, and increasing duration of temperature conditioning. Ripening capacity developed much more rapidly at 10 °C than at −0.5 °C. Useful durations of temperature conditioning at 10 °C were limited by fruit softening below acceptable values of shipping firmness. However, sequential combinations of ethylene and temperature conditioning at both −0.5 and 10 °C were identified wherein post-conditioning shipping firmness was acceptable.     

Induction of ripening capacity in ‘Packham's Triumph’ and ‘Gebhard Red D’Anjou’ Pears by temperature and ethylene conditioning

Methods were tested for rapid induction of ripening capacity in ‘Packham's Triumph’ and ‘Gebhard Red D’Anjou’ pears in order to facilitate early marketing. Fruit of each cultivar were harvested at the onset of maturity and conditioned to develop ripening capacity by exposure to 100 μL L⁻¹ ethylene at 20 °C for 0, 24, 48, or 72 h, followed by varying durations of temperature conditioning at −0.5 or 10 °C. Ripening capacity was tested by measuring fruit firmness after 7 d at 20 °C after completion of conditioning treatments. Fruit firmness was also measured after conditioning but before ripening, and was designated “shipping firmness,” indicative of the potential for the fruit to withstand transport conditions without physical injury. With temperature conditioning at −0.5 °C only, ‘Packham's Triumph’ pears needed 45 d to develop ripening capacity, while ‘Gebhard Red D’Anjou’ pears were not capable of fully ripening after 60 d, the longest duration tested. Using ethylene only, 72 h exposure was necessary to develop full ripening capacity in both cultivars, and adequate shipping firmness was maintained. Using temperature conditioning at 10 °C, ripening capacity in ‘Packham's Triumph’ and ‘Gebhard Red D’Anjou’ developed within 10 and 20 d, respectively, but shipping firmness in ‘Gebhard Red D’Anjou’ was compromised at 20 d. In both cultivars, 24 or 48 h in ethylene followed by 5 d at 10 °C induced ripening capacity while maintaining adequate shipping firmness.     

Numerical Simulation of Flow field and Temperature field in Combustion Chamber Widened Suddenly

The flowfield and temperature field are numerically Simulated by the mathematical model of the fluid flow and heat transfer in circular combustion chamber widened suddenly. The distributions and influence factors of the flow field and temperature field are studied in it. The results have the guiding significance for the design of combustion chamber. The mathematical models can serve as the quantitative analysis methods for design.     

Dynamics of ascorbic acid in ‘Braeburn’ and ‘Gala’ apples during on-tree development and storage in atmospheres conducive to internal browning development

The underlying causes as well as chemical and biochemical alleviation for CO₂-induced browning in apple fruit are poorly understood. Ascorbic acid (AsA) dynamics in ‘Braeburn,’ a susceptible cultivar, and ‘Gala’, a resistant cultivar, were evaluated during on-tree development and storage at 0.5 °C in air or controlled atmospheres (CA) containing 1 kPa O₂ and 1, 3 or 5 kPa CO₂. ‘Braeburn’ fruit treated with diphenylamine (DPA) was also stored for 1 month to determine effects on browning incidence and AsA concentration. ‘Braeburn’ apples had significantly higher (p ≤ 0.05) AsA levels than ‘Gala’ during on-tree development, and storage. No correlation between AsA and maturity/ripening indices for ‘Braeburn’ or ‘Gala’ was apparent. Histochemical localization of fruit AsA showed a staining intensity consistent with the quantity analytically determined, and showed that AsA is diffusely distributed throughout the cortex in both cultivars during on-tree development. During storage, AsA was localized to the periphery of brown tissue in ‘Braeburn’ and to the coreline and cortex proximal to the peel in ‘Braeburn’ and ‘Gala’ tissues. DPA decreased browning development during storage, however, no correlation between DPA treatment and AsA quantity in healthy or brown cortex tissue was observed. The results indicate AsA quantity alone is not an indicator of CO₂ sensitivity in these two cultivars.     

Low-temperature induction of ripening capacity in ‘Comice’ and ‘Bosc’ pears as influenced by fruit maturity

The relationship between fruit maturity at harvest and the duration of postharvest exposure to ?1 °C required to induce ripening capacity was studied in ‘Comice’ and ‘Bosc’ pears. As fruit of both cultivars were harvested progressively later, shorter durations of exposure to ?1 °C were required to induce ripening capacity. The relationship between the duration of conditioning at ?1 °C and the fruit flesh firmness after 7 d at 20 °C was well-described by second-order polynomial equations. These equations were used to determine the number of days at ?1 °C required to induce ripening capacity for each harvest date. A linear relationship was observed between the number of days after fruit in the orchard reached maturity that fruit were harvested and the number of days of low-temperature conditioning needed to induce ripening capacity. This relationship may be used to predictively estimate the duration of low-temperature conditioning required to induce ripening based on harvest date.     

Effect of 1-methylcyclopropene on ripening of ‘Canino’ apricots and ‘Royal Zee’ plums

‘Canino’ apricots and ‘Royal Zee’ plums were treated with 1000 nl l⁻¹ 1-methylcyclopropene (1-MCP) at 20 °C for 20 h following harvest before 0 °C storage. After 5 days storage for apricots and 10 days for plums and after 30 days storage for both, fruit were moved to 20 °C for ripening. In addition, apricots were stored for 20 days and then treated with 1-MCP concentrations of 10, 100 and 1000 nl l⁻¹ at removal and held for ripening. Ethylene production and respiration rate, as well as fruit quality of apricots varied with treatment. Ethylene production was efficiently inhibited by 1000 nl l⁻¹ 1-MCP in fruit treated after storage but not in fruit treated before storage. Fruit softening was associated with ethylene production and affected by 1-MCP in a concentration dependent manner when treated after storage, while 1-MCP did not affect softening in prestorage treated fruit. The color change of fruit was ethylene-independent and not affected by 1-MCP. Internal flesh browning was decreased by 1-MCP regardless of the concentration when treated after storage, while it was enhanced in fruit treated before storage. Decay development in apricots was decreased by 1-MCP in a concentration dependent manner. Ethylene production and respiration in ‘Royal Zee’ plums was greatly inhibited by 1-MCP during ripening after both short-term (10 day) and long term (30 day) storage. Parameters associated with ripening processes were decreased significantly by 1-MCP, including softening, color change, and loss of titratable acidity. These data demonstrate that 1-MCP has potential to delay ripening of apricots and plums, but the cultivar, maturity of fruit, and time of application must be chosen carefully. It is suggested that 1-MCP is more efficient for extending the shelf life and improving the quality of ‘Canino’ apricots directly marketed or after storage, whereas it might be a potent compound for extending both storage period and shelf life of ‘Royal Zee’ plums.     

Detection of downy and powdery mildew resistance QTL in a ‘Regent’ × ‘RedGlobe’ population

One hundred and eighty six F₁ plants from a ‘Regent’ × ‘RedGlobe’ cross were used to generate a partial linkage map with 139 microsatellite markers spanning all 19 chromosomes. Phenotypic scores for downy mildew, taken over two years, confirmed a major resistance QTL (Rpv3) against downy mildew in the interval VVIN16-cjvh to UDV108 on chromosome 18 of ‘Regent’. This locus explained up to 62 % of the phenotypic variance observed. Additionally a putative minor downy mildew resistance locus was observed on chromosome 1 in one season. A major resistance locus against powdery mildew (Ren3) was also identified on chromosome 15 of ‘Regent’ in the interval UDV116 to VChr15CenGen06. This study established the efficacy of and validated the ‘Regent’-derived downy and powdery mildew major resistance genes/QTL under South African conditions. Closely linked SSR markers for marker-assisted selection and gene pyramiding strategies were identified.     

Changes in volatile production and sensory quality of kiwifruit during fruit maturation in Actinidia deliciosa ‘Hayward’ and A. chinensis ‘Hort16A’

Although volatiles have been previously studied in kiwifruit (Actinidia spp.), there has been no co-ordinated study of volatile release and softening through the full edible period. In this report, the two most important commercial cultivars A. deliciosa ‘Hayward’ and A. chinensis ‘Hort16A’ were evaluated for volatiles released at different ripening stages corresponding to their typical commercial shelf life, and compared to the sensory quality assessed by a trained taste panel. Gas chromatography–mass spectrometry data indicated that large amounts of straight-chain aldehydes and esters were the dominant volatiles in the two cultivars. In particular, butanoates, the main fruity esters in both fruit, significantly increased during ripening and an extremely high level of butanoates was found in the over-ripe fruit. Sensory results indicated that with fruit softening, some of the changes in volatile content could explain changes in fruit flavor detected by a trained panel, and differences in characteristic flavor of the two cultivars. The results have implications for fruit sample handling and volatile assessment.     

Chromosome locations of genes controlling ‘purple leaf base’ in rye and wheat

Summary Purple leaf base is expressed only if there is anthocyanin pigmentation in coleoptiles either in rye or in rye-wheat-additions. Genes controlling purple leaf base were found to be located on chromosomes 5R (An5), 4B (Ra2) and 6B (Ra3) using the trisomic set of rye cv. Esto and autoplasmic rye-wheat-additions, respectively.     

Effects of Sucrose Concentration on the Bulblet Formation and Growth of ‘Acheng’Garlic in vitro

以MS为基本培养基，用地方品种阿城紫皮大蒜茎尖为外植体进行离体培养试验。结果表明，随蔗糖浓度的提高，大蒜试管微鳞茎形成被促进，而鳞茎发生数呈下降趋势；蔗糖浓度在30，60，90 g/L时，鳞茎发生数无显著差异，但均与120 g/L蔗糖处理下的鳞茎发生数间存在极显著差异；此外，各个处理条件下形成的平均鳞茎直径与鳞茎鲜重间均存在着极显著差异，90g/L处理效果最佳。