2n gametes inSolanum tuberosum dihaploids

Pollen stainability over two years and microsporogenesis were investigated in seven dihaploids extracted fromSolanum tuberosum tetraploids (AVRDC-1287.19, Conchita, Merrimack and W231). Two dihaploids proved to be male-sterile and male gamete abortion is likely to be post-meiotic because a regular meiosis occurred. The other dihaploids proved to be partially male-fertile and 2n pollen producers, as well. Almost all clones showed predominantly the formation of parallel spindles. Correlations estimated between the observed abnormalities in spindle orientation and the meiotic products evidenced a high correlation between parallel/fused spindles and dyads. The dihaploids were also used as parents in crosses with tetraploids. One berry with 44 seeds was obtained from dihaploid AVI 24 used as pollen parent in 4x × 2x crosses. After 2x × 4x crosses, three dihaploids including the two male-sterile were found to be 2n egg producers. The formation of 2n gametes inS. tuberosum dihaploids is discussed in relation to a direct use of dihaploids in sexual polyploidization schemes to combine useful traits in a superior genotype at 4x level.     

Rate of Cooling Alters Chip Color,Sugar Contents,and Gene Expression Profiles in Stored Potato Tubers

When stored at temperatures below 10 °C, potatoes accumulate sucrose and the reducing sugars glucose and fructose. This process, cold-induced sweetening, has been studied extensively because potatoes with elevated reducing sugar contents produce undesirable, dark-colored products and acrylamide, a suspected carcinogen, during high-temperature cooking. Potatoes in commercial storages are cooled slowly, but many research studies have used potatoes cooled rapidly. In this study, effects of cooling rate and variety on chip color, sugars, and gene expression were examined. Sucrose and reducing sugar contents were substantially lower in slowly cooled than in rapidly cooled tubers of ‘Snowden’ and “MegaChip’ for the first 11 weeks after cooling to 3 °C began. Differences in gene expression for VInv, β-amylase, SPS, AGPase and GBSS were observed between cooling treatments and varieties. Overall, the data showed that cooling rate, time in storage, and variety influenced multiple aspects of cold-induced sweetening.     

Biotic interactions affecting potato production

Pest/pathogen interactions affecting potato production are reviewed. Many reported interactions in potatoes and other crops are best termed associations or interrelationships. True synergistics interactions can be expressed as Y = b₁ x₁ + b₂ x₂ + b₃ (x₁ x₂) + - b_n x_n + e in which Y is a measure of plant growth, b₁, b₂, b_n are constants, x₁, x₂, x_n are independent variables and e is the error term. Examples of interactions including pathogen vectors, and various interactions involving different viruses and biotic taxa and among biotic taxa (e.g., virus-virus, virus-fungus, fungusbacteria, and nematode-fungus) in potatoes are cited. It is included that important interactions do occur in potato production systems and that additional research is needed to identify unknown interacting factors and to elucidate mechanisms of those previously described. Particular needs exist for holistic or synoptic studies to identify the role of interacting factors in total crop management.     

Movement patterns of three freshwater fish species after upstream transportation by fishway in the Jangheung Dam

We investigated the post-passage movement patterns of three freshwater fish species, Carassius auratus, Hemibarbus longirostris, and Silurus asotus, frequently captured in a fishway trap as they were released into the lentic dam reservoir. Acoustic telemetry was used to monitor fish movement. Acoustic tags were attached to 10 individuals (C. auratus, [n = 6], Ca1–6; H. longirostris, [n = 2], Hl1 and Hl2; and S. asotus, [n = 2], Sa1 and Sa2). The individual (Sa1) was particularly monitored to changes of vertical distribution between day and night a depth transmitter. The lentic species, C. auratus and S. asotus, were grouped into those that moved into upper streams (Ca1, Ca2, Ca3, and Sa1) and those that stayed in the reservoir (Ca4, Ca5, Ca6, and Sa2); all individuals utilized almost the entire area of the reservoir. However, H. longirostris, which favor lotic environments, showed different responses; one (Hl1) immediately moved into one of upper the streams, whereas the other (Hl2) utilized the entire dam reservoir area. No significant correlations were observed between size of the C. auratus individuals (total length and total weight) and monitored parameters (total movement distance, movement distance per day, and number of receivers encountered). Moreover, S. asotus used the water at a mean depth of 2.89 ± 1.52 m, and its vertical distribution changed more actively during the night than that during the day. Therefore, the efficacy of the Jangheung Dam fishway could be improved through release of the confluence of the inflow streams at the dam reservoir, which would provide both lentic and lotic environments without extended migration for fish.     

Assessment of sediment exclusion efficiency for several modified labyrinth weirs

A trapezoidal labyrinth weir is a general transverse hydro-structure typically placed across rivers that causes longitudinal sediment discontinuity and affects riparian ecological system. A sediment exclusion labyrinth (SEL) weir is a modification designed to increase sediment exclusion from upstream to downstream over or through it. Hydraulic model experiments were carried out in straight rectangular cross-sectional open channel (15 m in length and 0.82 m in width). Four different shapes of weirs were examined. type 1 was a general labyrinth weir, whereas types 2–4 were SEL weirs with an inclined bottom slope (type 2), open slots (type 3), and reversed-wedge type holes (type 4). Standard sand (Jumunjin, Korea, d ₅₀ = 0.56 mm, σ _g = 1.48, SG = 2.65) was uniformly supplied upstream using an in-house grooved drum, and sediment exclusion efficiency was calculated from the ratio of sediment amount to excluded sediment yield for each type of weir. Higher efficiencies were founded in all SEL weirs compared with the sediment exclusion efficiency of the type 1 weir. In particular, type 2 and type 4 weirs were easy to construct and their flow patterns and hydraulic performance were similar to those of type 1. Finally, their sediment exclusion efficiencies were higher under a normal water level (F _r ≤ 0.2), whereas the type 3 weir was the pattern favorable for a high water level (F _r > 0.2) because its discharge capacity was significantly higher. Sediment exclusion characteristics were analyzed in terms of flow rate based on the decomposition analysis of residual sediment particle size distribution. It is expected that the results from this study will be used to design SEL weirs as basic materials if more hydrodynamic parameters are studied and combined with field monitoring.     

Diversity in nuclear DNA content and ploidy level of Hedychium species and hybrids

Hedychiums are multipurpose plants cultivated as ornamentals because of their multicolor and showy and scented flowers and as medicinal plants because of their essential oils that have been found to possess antimicrobial and insecticidal properties. There is often taxonomic and botanical confusion about Hedychium species and cultivars because of the apparent existence of more than one cytotype within several Hedychium species, most likely because of the ease with which these species hybridize. Nuclear DNA content (2C-DNA) was determined for the first time in 23 Hedychium species and hybrids. The 2C-values ranged from 1.70 pg to 3.98 pg. We also determined the chromosome number of one species, Hedychium stenopetalum, which was found to be diploid (2n = 2x = 34), supporting the widely held view that the basic chromosome number in Hedychium is x = 17, and the existence of different cytotypes is most probably attributable to natural hybridization. Our results should be helpful not only in clarifying the botanical and taxonomic confusion in Hedychium but also in paving the way for a sound breeding program for this increasingly important ornamental ginger.     

Frequency of 2n pollen in diploid hybrids betweenSolanum phureja Juz. & Buk. andSolanum chacoense Bitt.

Summary Solanum phureja (PP)xSolanum chacoense (CC) hybrid families (PC) were evaluated for pollen fertility and frequency of 2n pollen in two seasons in Morocco. PP clones produced high frequencies of 2n pollen, whereas CC clones produced none. The percentage of plants with 2n pollen ranged from 2 to 63% among 20 PC families and was consistent in some PC families over two growing seasons, whereas others varied between fall and spring growing seasons. The expected ratio of 2n to non-2n pollen-producers within a PC family based on a single recessive gene model [i.e. 1∶0 with CC homozygous dominant (PsPs) or 1∶1 with CC heterozygous (Psps)] was observed in only 5 of 20 progenies. Narrow sense heritability was 0.71, allowing gain from further selection. Only clones producing more than 10% 2n pollen exhibited more stable expressivity across seasons. Scientific Journal Series Article 17811 of the Minnesota Agricultural Experiment Station supported in part by the US Agency for International Development, contract no. 608-0160, IAV Morocco Project.     

Selection of monoploids for protoplast fusion and generation of intermonoploid somatic hybrids of potato

The union of potato monoploid genotypes (2n=1x =12) through protoplast fusion may result in vigorous somatic hybrids due to a reduction of the “genetic load” normally present in this highly heterozygous tetraploid (2n=4x=48) crop. More than 100 androgenic monoploids derived from diploid (2n=2x=24)Solanum phureja Juz. & Buk. andS. chacoense Bitt. xS. phureja clones were evaluated in field trials during 1996 and 1997 to identify the most promising genotypes for protoplast fusion experiments. Compared to the total population, the 1996 selected genotypes had higher means for tuber number (30.1 vs 11.2 tubers/plant), average tuber weight (3.0 vs 1.8 g/tuber) and total yield (66.1 vs 20.4 g/plant). Similarly, the 1997 selected genotypes had higher means for tuber number (42.8 vs 25.4 tubers/plant), average tuber weight (3.6 vs 2.5 g/tuber) and total yield (114.0 vs 63.4 g/plant) compared to the total population. The 31 selected monoploid genotypes from 1996-97 varied in their response to protoplast isolation and culture from no growth (9), cell enlargement (5), limited cellular divisions (8), callus formation (5) to plant regeneration from callus (4). Chemical fusion and electrofusion produced three groups of intermonoploid somatic hybrids. Polymorphic simple sequence repeat (SSR) loci enabled distinction of somatic hybrids from parental somaclones. Rapid DNA extraction with SSR analysis enabled screening of calluses to identify somatic hybrid tissue prior to plant regeneration. The somatic hybrids were highly polyploid, mostly hexaploid (2n=6x=72), possibly due to fusion of endopolyploid protoplasts and/or chromosomal doubling during plant regeneration.     

The Green Fence of Chinese Hibiscus (Hibiscus rosa-sinensis L.) Prevents Pollen Dispersal of Transgenic Rice (Oryza sativa)

Abstract

Transgene escape mediated by pollen dispersal is one of the preeminent concerns about genetically modified crops, including rice. In this study, the rice pollen donor of non-glutinous Oryza sativa ssp. japonica cv. ‘Tainung 67’ [TNG 67] had a greater potential of pollen flow, which was shown by the greater quantity, germination rate, and viability of pollen, than the other rice pollen donor of transgenic AAN. The pollen-mediated gene flow was detected by the frequency of outcrossed seeds in a “checker-board pattern” and alternating row arrangement of rice pollen donor (TNG 67 or AAN) and pollen recipient (glutinous rice ‘TNG 73’) in the fields. We conducted field experiments to assess rice pollen dispersal with or without a “green” fence of Chinese hibiscus, Hibiscus rosa-sinensis L., of approximately 2 m in height and 0.6 m in thickness. Without a green fence, the outcrossing rate of TNG 73 seeds decreased with increasing distance from the pollen donor, from 1.68% at 1 m to 0.01% at 35 m, with no outcrossing beyond 40 m. The outcrossing rate varied with the direction of pollen donor, from 0.05% in the northeastern direction to 0.78% in the southern direction, which was caused by prevailing wind direction. With the green fence, no seeds of TNG 73 were outcrossed. Since a buffer zone of at least 40 m is needed to prevent outcrossing of rice by pollen dispersal in an open field, planting of Chinese hibiscus around the rice field as a green fence would be an effective measure for preventing transgene escape mediated by pollen flow.     

Arsenic in irrigated water,soil, and rice: perspective of the cropping seasons

Arsenic contamination of shallow groundwater and related health problems are threats for the millions in endemic regions of West Bengal. Contamination of rice grain creates the food chain pathway of mineral arsenic besides drinking water contamination. Present study concentrated on association of arsenic concentration in irrigated water, paddy field soil and rice with the cropping seasons. Irrigated ground water arsenic concentration decreased significantly (p = 0.007) from summer (median 0.42 mg l^?1) to winter (median 0.35 mg l^?1). Carried over effect created significant decrease (p = 0.03) of paddy field soil arsenic concentration from summer (median 8.35 mg kg^?1) to winter (median 6.17 mg kg^?1). Seasonal variation was observed in rice straw (p = 0.03) but not in husk (p = 0.91). Arsenic concentration decreased significantly (p = 0.05) in the rice grains collected in winter season (median 0.23 mg kg^?1) than the samples collected in the summer season (median 0.30 mg kg^?1). In conclusion, seasonal effects need to be considered in case of human health risk assessment from arsenic consumption.     

Losses during Storage of Potato Varieties in Relation to Weather Conditions during the Vegetation Period and Temperatures during Long-Term Storage

Degradation of harvested tubers due to water loss, sprouting, and disease can cause severe economic difficulties in the cultivation of potatoes (Solanum tuberosum). This study evaluated the storage losses of new varieties of potato and determined the sprouting dates of potatoes stored at different temperatures. Additionally, this study evaluated the influence of weather conditions during the vegetative growth period on the date of sprouting in storage. After storage at three different temperatures (3, 5, and 8 °C), we estimated natural losses and losses caused by sprouting or the development of disease. The potato varieties stored at 3 °C, and 5 °C had similar weight losses (8.8% and 9.3%, respectively), but the potatoes stored at 8 °C had higher losses (10.8%). The average potato losses caused by disease ranged from 0.6% to 10%. The onset of sprouting of potatoes stored at 8 °C depended on the variety and began in the 20 day of December. Storage at 5 °C delayed sprouting by about 50 days compared with storage at 8 °C. Weather conditions (hot and rainy) during vegetative growth of the plants also influenced sprouting date, natural losses, and the amount of disease during storage. Our data showed a significant correlation between the hydrothermal coefficient during the vegetative period and the date of sprouting of potatoes during storage.     

Radiation utilization efficiency,latent heat flux,and crop growth simulation in irrigated rice during post-flood period in east coast of India

To study the radiation utilization efficiency, latent heat flux, and simulate growth of rice during post-flood period in eastern coast of India, on-farm trial was conducted with three water regimes in main plots (W ₁ = continuous flooding of 5 cm, W ₂ = irrigation after 2 days of water disappearance, and W ₃ = irrigation after 5 days of water disappearance) and five nitrogen levels in subplots (N ₁ = 0 kg N ha^?1, N ₂ = 60 kg N ha^?1, N ₃ = 90 kg N ha^?1, N ₄ = 120 kg N ha^?1, and N ₅ = 150 kg N ha^?1) on a rice cultivar, ‘Lalat’. Average maximum radiation utilization efficiency (RUE) in terms of above ground dry biomass of 2.09 (±0.05), 2.10 (±0.02), and 1.9 (±0.08) g MJ^?1 were computed under W ₁, W ₂, and W ₃, respectively. Nitrogen increased the RUE significantly, mean RUE values were computed as 1.60 (±0.07), 1.78 (±0.02), 2.060 (±0.08), 2.30 (±0.07), and 2.34 (±0.08) g MJ^?1 when the crop was grown with 0, 60, 90, 120, and 150 kg ha^?1 nitrogen, respectively. Midday average latent heat flux (on clear days) varied from 7.4 to 14.9 and 8 to 13.6 MJ m^?2 day^?1 under W ₂ and W ₃ treatments, respectively, at different growth stages of the crop in different seasons. The DSSAT 4.5 model was used to simulate phenology, growth, and yield which predicted fairly well under higher dose of nitrogen (90 kg and above), but the model performance was found to be poor under low-nitrogen dose.     

普通小麦-滨麦及其衍生系的染色体组成分析

滨麦[Leymus mollis(Trin.)Pilger,NsNsXmXm,2n=28]属禾本科(Poaceae)小麦族(Triticeae)大麦亚族(Hordinae)赖草属(Leymus Hochst.)的一个多年生四倍体植物,蕴含着丰富的小麦改良优异基因,是小麦育种的重要三级基因资源。为给普通小麦-滨麦种质类型的创制、筛选和鉴定提供参考依据,本研究通过细胞学观察、顺序荧光原位杂交(fluorescence in situ hybridization,FISH)-基因组原位杂交(genomic in situ hybridization,GISH)及分子标记等技术分别对普通小麦7182、滨麦及其高世代衍生系的染色体组成进行了研究。采用寡核苷酸探针pSc119.2和pTa-535相结合的技术绘制出普通小麦7182所有染色体的FISH标准核型图。初步推断出滨麦的染色体核型公式2n=4x=28=22m(6sat)+6sm。同时通过FISH-GISH技术鉴定出两种类型的普通小麦-滨麦高世代衍生系M47和M39,染色体组成分别表示为2n=56=42T.a+14L.m、2n=56=44T.a+12L.m。     

Germplasm transfer from the wild tetraploid speciesSolanum acaule bitt. to the cultivated potato,S. tuberosum L. using 2N eggs

Solanum acaule Bitt. (acl ¹, 2n=4x=48 and 2n=6x=72) is a wild potato species in which resistance to adverse biotic and abiotic agents has been found. The tetraploid subspeciesacaule andaemulans cannot be easily crossed with the common potato,S. tuberosum L. Grouptuberosum (tbr, 2n=4x=48) because the development of the endosperm in the hybrid seed is abnormal. Since 4xacl behaves as a diploid in intra and interploidy crosses, it was postulated that the hybridization barrier withtbr could be overcome if the wild species produced 2n gametes. One hundred and ninety-seven plants of 4xacl (22 introductions) were screened for pollen of heterogeneous size; only two plants produced this type of pollen, with 3% and 5% of pollen in the large class, respectively. On the other hand, 427 plants (47 introductions) were screened for 2n eggs through controlled crosses withtbr. Forty-one plants (13 introductions) produced 219 berries of which 46 contained at least one plump seed. Seed from berries with low seed set gave rise to hexaploid hybrids possibly through the functioning of 2n eggs from 4xacl. A sample of these hybrids was successfully backcrossed as female parents totbr, giving rise to 5x BC₁ progenies. These BC₁ progenies could be easily back-crossed totbr, yielding tetraploid or near tetraploid BC₂ plants.     

Effect of fertilization on crop responses and solute transport for rice crop in a sub-humid and sub-tropical region

In order to increase the efficacy of water and control the losses of fertilizer, it is necessary to assess the influence of level of fertilization on crop responses, movement and balance of water and solutes from fertilizers in the root zone. With this goal, the reported study was undertaken to determine the effect of fertilization on crop responses and fertilizer solute transport in rice crop field in a sub-humid and sub-tropical region. Field experiment was conducted on rice crop (cultivar IR 36) during the years 2003, 2004, and 2005. The experiment included four fertilizer treatments comprising different levels of fertilizer application. The fertilizer treatments during the experiment were: F₁ = control with N:P₂O₅:K₂O as 0:0:0 kg ha^?1; F₂ = fertilizer application of N:P₂O₅:K₂O as 80:40:40 kg ha^?1; F₃ = fertilizer application of N:P₂O₅:K₂O as 120:60:60 kg ha^?1 and F₄ = fertilizer application of N:P₂O₅:K₂O as 160:80:80 kg ha^?1. The results of the investigation revealed that the magnitudes of crop parameters such as grain yield, straw yield, and maximum leaf area index increased with increase in fertilizer application rate. The levels of fertilization had very little effect on water loss via deep percolation and water use by the crop. The levels of fertilization had considerable effect on N leaching loss and uptake of N whereas it had no significant impact on leaching loss of water-soluble phosphorus. This indicated that PO₄-P leaching loss was very low in the soil solution as compared to nitrogen due to fixation of phosphorus in soils. The results also revealed that increase in level of fertilization increased water use efficiency considerably by increased crop yield. From the observed data of nutrient use efficiency, crop yield and environmental pollution, the fertilization rate of N:P₂O₅:K₂O as 80:40:40 kg ha^?1 (F₂) was the most suitable fertilizer treatment for rice crop among studied treatments.     

Effects of various organic amendments on organic carbon pools and water stable aggregates under a scented rice–potato–onion cropping system

Pools of organic carbon are quantified from the soil samples under scented rice crop from different soil layers (0–10, 10–20, and 20–30 cm) under 9 years’ long-term trials with five treatments in scented rice–potato–onion cropping system. These treatments were 100 % NPK (NPK), 50 % recommended NPK through mineral fertilizers + 50 % N as FYM (NPK + FYM), FYM + vermicompost (VC) + neem cake (NC) each equivalent to one-third of recommended N (FYM + VC + NC), 50 % N as FYM + biofertilizer for N + bone meal to substitute phosphorus requirement of crops + phosphate solubilizing bacteria (FYM + BFN + BM + PSB), FYM + vermicompost + neem cake each equivalent to 1/3rd of recommended N + PSB (FYM + VC + NC + PSB). SMBC (479 mg kg^?1), HWEOC (373 mg kg^?1), CWSCHO (235 mg kg^?1), HWSCHO (839 mg kg^?1), and ASCHO (180 mg kg^?1) were found to be the highest in the soil treated with FYM + VC + NC + PSB and the lowest with NPK. The quantity of hot water-extractable carbohydrate content is highest amongst cold water, dilute acid and hot water extractable carbohydrate that decreases with the soil depth irrespective of treatments, except CWEOC. Soil microbial biomass carbon (SMBC) shows significant correlation with CWEOC (r = 0.60**), HWEOC (r = 0.94**), CWSCHO (r = 0.75**), HWSCHO (r = 0.83**), and ASCHO (r = 0.83**) that primed for better aggregate stability irrespective of soil layers up to 30 cm depth. This indicates that labile carbon pools, most specifically water-soluble carbon, carbohydrate, microbial biomass, could be a suitable indicator for evaluation of soil quality, particularly in relation to soil aggregation.     

Discrepancy between spindle anomalies and 2N pollen production insolanum interspecific hybrids

The cytological basis of 2n pollen production was studied in a diploidSolanum progeny coming from a cross between aS. tuberosum S. chacoense hybrid which does not produce2n pollen (T710) and a S.phurejar S. tuberosum hybrid (W5295.7) which does. Both parental clones showed anomalous orientation of spindles at Metaphase II of microsporogenesis, but only clone W5295.7 produced dyads. All plants of the progeny T710 × W5295.7 showed anomalous spindles at Metaphase II, but only 60% of them produced 2n pollen, thus evidencing a discrepancy between spindle anomalies and dyad/2n pollen production. This may suggest that both parallel and fused spindles are a necessary but insufficient condition for 2n pollen production, and that some other mechanisms expected to be more highly correlated with them may be involved in 2n pollen production in this population.     

Aminopyralid Residue Impacts on Potatoes and Weeds

Aminopyralid is used in Alaska to control certain invasive weed species; however it appears to have an extended soil half-life in interior Alaska resulting in carry-over injury in potatoes. Field studies at three experiment stations in Delta Junction, Fairbanks, and Palmer, Alaska were established to determine the dose–response of weeds and above and below ground potato growth to soil-applied aminopyralid (0, 8, 15, 31, 62, and 123 g ae ha^?1) . Both prostrate knotweed and narrowleaf hawksbeard were susceptible to aminopyralid. At Delta Junction and Fairbanks, visual injury of potatoes greater than 25 % was observed at 15 g ae ha^?1 aminopyralid, whereas at Palmer visual injury was greater than 40 % at 8 g ae ha^?1, the lowest rate tested. Potato tuber production was reduced by aminopyralid at rates of 15 g ae ha^?1 and above at both Delta Junction and Palmer. Sub-samples of potato tubers from Delta Junction and Palmer were analyzed for aminopyralid content and grown out to determine if aminopyralid in tubers would reduce subsequent growth. The aminopyralid concentration in potato tubers increased with increasing field application rates, with 30 ppb extracted from tubers grown at the highest application rate (123 g ae ha^?1). All plants grown from daughter tubers except from control plots in Palmer exhibited injury symptoms. The number of emerged shoots, and shoot height decreased with increasing aminopyralid concentrations in the tuber, with injury rates greater than 70 % at 8 g ae ha^?1.     

Seed set in 4x x 2x crosses as related to 2n pollen frequency

Seeds per fruit following 4x × 2x crosses in potato are roughly related to the frequency of 2n pollen. Our goal was to examine precisely the relationship between frequency of stainable 2n pollen and seeds per fruit (s/f) in 4x × 2x crosses. A 4x cultivar with high female fertility and 21 2n pollen producing 2x hybrids were used as seed and pollen parents, respectively. 2n pollen frequencies varied from 1 to 99% in the 2x hybrids and seed set ranged from 0 to 305 s/f in 4x×2x crosses. Mean seeds per fruit increased in response to increases from 1 to 50% 2n pollen, but did not increase in response to using a pollen sample with a 2n pollen frequency over 60%. Seed set averaged 11 s/f corresponding to pollen samples with 1–5% 2n pollen, 50 s/f at 10–20%, 125 s/f at 20–30%, and over 170 s/f at 2n pollen frequencies over 60%. Seed set in 210 control 4x × 4x crosses indicated that equivalent seed set occurs in 4x × 2x crosses when 2n pollen frequencies are over 20–30%. The 2x hybrids differed in mean and variation of 2n pollen frequencies and seed set in 4x × 2x crosses. One 2x hybrid with a meiotic aberration (sy-3) resulting in all univalents at Metaphase I (ordinarily leading to male sterility) and parallel spindles (ps) at Anaphase II had close to 100% 2n pollen (of the stainable pollen) and gave equivalent s/f in 4x × 2x crosses to s/f in 4x × 4x crosses. It is apparent that ample seed set occurs for using the 4x × 2x breeding scheme with 2n pollen frequencies over 10% and that even very low 2n pollen frequencies (1–10%) provide seed for the 4x×2x breeding approach.     

Variability of Phytonutrient Content of Potato in Relation to Growing Location and Cooking Method

Potato has a defined complement of metabolites that contribute to the human diet. Among these are the carotenoids and anthocyanins. Carotenoids are found in all potatoes in the flesh. White-fleshed varieties have 50 to 100 μg per 100 g fresh weight (FW), while moderately yellow-fleshed varieties will generally possess from 100 to 350 μg per 100 g FW. The more intensely yellow-fleshed genotypes, which may look orange, at the higher extremes are at levels above 1,000 μg per 100 g FW. The highest level published is 2,600 μg per 100 g FW in diploid germplasm derived from South American Papa Amarilla cultivars. Potato generally has predominantly lutein, a xanthophyll which is also found in the human retina, and must be obtained in the diet. The genotypes with extremely high levels of total carotenoids have zeaxanthin, an isomer of lutein, which is also present in the human retina. Anthocyanins are present in red- or purple-skinned and fleshed varieties. Total anthocyanins range from 1.5 mg to 48 mg per 100 g FW in a solidly pigmented purple-skinned, purple-fleshed breeding line. The degree of pigmentation in the flesh appears to be under polygenic control. Anthocyanins are potent antioxidants and anti-inflammatory substances. The level of total anthocyanins is correlated with antioxidant level (r?=?0.94, P?<?0.001). Several methods of cooking interacted with genotypes in the antioxidant level remaining after cooking compared to raw potatoes. No method of cooking completely eliminated antioxidant activity, while boiling appeared to increase it compared to raw potato in the case of the most highly pigmented clone.