Molecular analysis of genetic variation in potato (Solarium tuberosum L.). II. International cultivar spectrum

Summary Seventy-five commercial potato cultivars orginating from North America, Europe and Japan were analysed using AFLP and SSR markers to assess their genetic relationships. Results of cluster and principal coordinate analysis reflect in most cases known pedigree information. Independent of the marker system used it was possible to identify groups based on their geographical descent. Cultivars from Central and East Europe formed two overlapping pools. An Anglo-American gene pool was also identified. Additionally, principal coordinate analysis based on AFLP data uncovered that this pool is subdivided in two groups. One group is more closely related to the European pools and dominated by cultivars with immediate background of cv. Kathadin. Japanese cultivars gave no distinct cluster.     

Molecular analysis of genetic variation in potato (Solarium tuberosum L.). I. German cultivars and advanced clones

Summary The genetic variation of 69 potato cultivars and advanced clones from a commercial German breeding programme were analysed by using 6 AFLP primer combinations or 26 microsatellite (SSR) primer pairs. Available pedigree information was reflected in genetic distances. Cluster and principal coordinate analysis showed clear patterns of related genotypes with slight differences dependent on the marker system used. AFLP analysis, in particular, differentiated groups based on their genetic background: Clones with common ancestors separated from unrelated cultivars. A minimum of 150 polymorphic markers were necessary to obtain reliable results. Diversity index, effective multiplex ratio, and the resulting marker index were calculated for both marker systems. Their use for parent selection is discussed in relation to achieving maximum heterosis.     

Optimizing the propagation of potato (Solanum tuberosum L.) by stem cuttings

Stem cuttings from potato plants are frequently used in multiplication programs for disease-free cultivars. The survival of these leafy cuttings is often very poor, and thus various techniques were investigated which were designed to increase rooting and cutting survival. Stock plants of cultivars “Caribe,” “Jemseg,” “Keswick,” “Russet Burbank,” “Sable,” “Sebago” and “Shepody” were grown in the greenhouse under long days. Promoting growth of the axillary shoots was successfully achieved by shading the shoot apex with aluminum foil. Trimming the outer leaves of the cuttings was deleterious to both survival and rooting. A rooting hormone improved root initiation and development, and the use of shade cloth or intermittent mist increased survival by reducing wilting. A rooting substrate of vermiculite: perlite (1:1) provided sufficient aeration, support and drainage for the cuttings. Antitranspirants sprayed on the stock plants prior to the excision of cuttings and also on the excised cuttings did not improve rooting or survival. The addition of activated charcoal (1% w:w) increased rooting of the cuttings and improved vigor of potted plants obtained from the cuttings.     

Determination of the glycoalkaloids α-solanine and α-chaconine levels in 18 varieties of potato (Solarium tuberosum L.) grown in Oman

Summary The glycoalkaloid content in 18 potato varieties grown in Oman was measured by HPLC using peel and flesh tissues. The total glycoalkaloid content of the tubers was found to be variety dependent and varied greatly between the 18 varieties. The total glycoalkaloid in the tubers of seven varieties was within the safe limit of ≤200 mg kg^{− 1} FW recommended for food safety, whereas the remaining 11 varieties exceeded this upper limit. The principal glycoalkaloids α-chaconine and σ-solanine were present in higher concentration in the peel than in the flesh of all varieties with the former being the principal alkaloid in the peel. The flesh of all of the 18 potato varieties contained total glycoalkaloid levels lower than the upper safety limit. The leaves of the 18 potato varieties were also analyzed for glycoalkaloids. The levels of glycoalkaloids in expanding leaves were higher than that of expanded leaves with the exception of six varieties. The principal glycoalkaloid in expanding and expanded leaves was α-chaconine. No correlation was observed between the glycoalkaloids levels of in the leaves and tubers.     

Shoot development and flowering in potato (Solanum tuberosum L.)

Summary The shoot system of potato is a configuration of stems with terminal inflorescences. In this review, shoot development is quantified in terms of stem production, while stem development is quantified in terms of leaf and flower primordia production per stem, which are functions of the rates and the durations of primordia initiation. The effect of the position of the stem in the shoot system on number of leaves and flowers per stem is also evaluated. Flowering of individual stems is described by the ‘time to flower primordia initiation’ (expressed in number of leaves produced) and ‘flower production’ (a function of the number and the development of flower primordia). At warmer temperatures and longer daylengths the number of leaves and flower primordia per stem, and the number of stems per shoot increase by prolonging stem production and primordia development. Temperature and photoperiod also affect flower primordia survival by altering assimilate production and partitioning. The photothermal response of the number of leaves per stem is small compared to the response of stem production; at higher temperatures, flower primordia survival becomes the principal factor determining flower production. The similarity of the signals leading to flower primordia initiation and tuberization, and the relation between shoot and tuber growth are discussed.     

分子标记在菠萝研究中的应用

介绍了分子标记技术在菠萝上的应用,主要包括种质鉴别、遗传多样性、亲缘关系、连锁图谱构建以及与优良农艺性状相关的分子标记的获得等方面的情况,并对存在的问题和应用前景进行了讨论。     

Cryopreservation of in vitro-grown meristems of potato (Solanum tuberosum L.) by encapsulation-vitrification

Summary Alginate coated meristems from in vitro-grown axillary buds of potato (Solanum tuberosum L.) were successfully cryopreserved by vitrification. Excised meristems were precultured on sucrose-enriched MS medium and then encapsulated. To induce dehydration tolerance (osmotolerance), encapsulated meristems were treated with a mixture of 2 M glycerol plus 0.6 M sucrose for 90 min. These encapsulated meristems were dehydrated with a highly concentrated vitrification solution (PVS2 solution) for 3 hr at 0°C prior to a plunge into liquid nitrogen. Successfully vitrified meristems developed shoots within 3 weeks after plating without intermediary callus formation. The average rate of shoot formation amounted to nearly 70%. No difference was observed in RAPD analysis using 17 primers between cryopreserved and non-treated plantlets. The cryogenic protocol was successfully applied to 14 cultivars. It was also confirmed that the encapsulated vitrified meristems produced much greater shoot formation than the encapsulated dried meristems. Thus, the encapsulation vitrification protocol appears promising for cryopreservation of potato germplasm.     

Ultrastructural changes in tubers of potato (Solanum tuberosum L.) affected by rust spot

Summary The medullary tissues of potato tubers affected by rust spot were embedded in resin, sectioned and stained for optical and electron microscopy. Under the optical microscope, the damaged zones were seen to have thickened and suberized cell walls, with cells partially or totally lacking starch. These features were confirmed by electron microscopy which revealed in relief the cell wall deformation and the characteristic presence, in the vacuole, of osmiophilic granules with a spongy appearance attached to the tonoplast, probable catabolic products of a disturbed metabolism. Separation and degeneration of the plasmalemma and the death of the cells were observed in tissues in the final stages of damage.     

利用分子标记鉴定四川省马铃薯品种

以15个马铃薯育成品种和引进品种为材料,采用微卫星分子标记技术鉴定供试马铃薯品种。研究检测了4个SSR位点在15份马铃薯育成品种(系)中的多态性。在15份马铃薯品种(系)中,共检测到等位基因26个,每对引物检测到的等位基因个数最少为5个,最多为10个,平均6.5个。PIC(Polymorphism information content)值最高为0.9288;最低为0.8597,平均PIC值为0.8857。仅利用少数几对高PIC值的SSR引物,即能将全部供试品种(系)区分,因此,SSR技术有利于高效准确的鉴定马铃薯品种。     

Unsaponifiable lipids from haulm and tuber sprouts of potato (Solanum tuberosum L.)

Summary Fractions containing Δ⁵- and Δ⁷-sterols, 4-methyl-sterols, triterpenic alcohols, tocopherols and hydrocarbons were isolated by TLC from petroleum ether extracts of the haulm and tuber sprouts of cv Désirée. Sterol and triterpenic alcohol fractions of unsaponifiable lipids of the haulm and tuber sprouts were found to contain twelve sterols and four triterpenic alcohols, respectively. 24R-4-stigmasten-3-on, Δ⁷, Δ⁷, lanosterol, cycloeucalenol and obtisufoliol have not been identified previously in unsaponifiable lipids from haulm and sprouts. In the hydrocarbon fractions of the haulm extract, C₂₃-to C₃₃-n-parafins, C₁₉-and C₃₁-cyclohexyl hydrocarbons, C₂₂-to C₃₈-olefins and squalene were identified, and in the hydrocarbon fractions of the tuber sprouts C₁₂-to C₂₆-olefins and squalene were identified.     

A rapid screening technique for drought resistance in potato (Solanum tuberosum L.)

Summary The reduction in growth in the dark of leaf dises floated over polyethylene glycol 6000 solution of water potential −0.4 MPa, relative to the growth of similar leaf dises floated over water for the same period, varied in the range 10–87% in 28 genotypes. The growth reductions in the genotypes tested were in general agreement with what is known about their drought resistance. Publication No. 906, Central Potato Research Institute, Simla.     

利用SSR引物分析西藏青稞种质资源的遗传多样性

为了评价西藏青稞种质资源的遗传多样性,用260对SSR引物对来自青藏高原主要农区的75份青稞育成品种、17份野生大麦、39份青稞地方品种和44份国外大麦材料的遗传多样性进行了分析.结果表明,从260对SSR引物中筛选出23对多态性高的引物,占筛选引物的8.1％.23对SSR引物在西藏野生大麦中共扩增出稳定、清晰的条带92条,多态性条带为81条,其比例为88.04％;在西藏青稞地方品种中共扩增出稳定、清晰的条带89条,多态性条带为78条,其比例为87.6％;在青稞育成品种中共扩增出稳定、清晰的条带109条,多态性条带98条,其比例为89.9％;在引进材料中共扩增出稳定、清晰的条带64条,多态性条带53条,其比例为82.8％.遗传多样性分析结果为青稞育成品种(0.9882)＞西藏野生大麦(0.8033)＞西藏青稞地方品种(0.5820)＞国外大麦材料(0.4218).聚类与主坐标分析表明,实验材料可以清楚的分为4类,西藏野生大麦分在两个类群,西藏青稞地方品种分在两个类群,引进大麦材料分在一个类群,青稞育成品种分在四个类群.同一来源地区的青稞育成品种遗传基础较为狭窄,不同地区间的青稞育成品种遗传差异较大.以上结果说明,在西藏青稞新品种选育和遗传改良中,在发掘和利用西藏野生大麦资源、西藏青稞地方品种资源的同时,更应该加强不同地区青稞育成品种资源的交换和配合使用.     

Transfer of PLRV resistance fromSolanum verrucosum Schlechdt to potato (S. tuberosum L.) by protoplast electrofusion

Summary Somatic fusions between an accession of the diploid wild speciesSolanum verrucosum and a dihaploid S.tuberosum genotype were produced in order to incorporate resistance to potato leafroll virus (PLRV). In total 15 somatic hybrids out of 16 regenerants were obtained. Identification of hybrids was based on additive RAPD patterns, general morphological characteristics, chromosome numbers and chloroplast counts in stomata guard cells. A field trial was performed with the hybrids, their two parents and the control cultivar Kennebec to assess field performance and phenotypic variability. Yield parameters varied considerably among somatic hybrids. Some of the hybrids gave significantly higher yields, tuber numbers and tuber weights than both parents. Pollen fertility of hybrids ranged from 19 to 77%. Twelve hybrids were found to be resistant to PLRV.     

Varietal and environmental effect on the glycoalkaloid content of potato (Solanum tuberosum L.)

The tubers of 14 potato varieties were analysed for glycoalkaloids. The level of glycoalkaloids in tubers of all the varieties analysed are within the safe limits for human consumption. The peels of tuber contained about 60–70% of the total glycoalkaloids present in the whole tuber. The levels of glycoalkaloids in leaves and tubers were correlated (r=0.865). There was a significant increase in the content of glycoalkaloids in peels of tubers exposed to sunlight. Glycoalkaloid contents increased at the rate of 1.9mg/100g fresh weight per day in peels of Kufri Jyoti tubers exposed to diffused sunlight.     

Isolation of solanidine from haulm and tuber sprouts of potato (Solanum tuberosum L.)

Summary The kinetics of enzymatic transformation of total glycoalkaloids (TGA) in haulm and tuber sprouts of potato to solanidine and the kinetics of solanidine isolation from plant material were studied. The optimum reaction conditions for the enzymatic TGA transformation were found for haulm to be: plant material to liquid phase 1:4 w/v, temperature 35°C, pH 5.4; and for tuber sprouts: plant material to liquid phase 1:3 w/v, temperature 37°C, pH 5.4. The. maximum degree of enzymatic transformation of TGA in haulm and tuber sprouts of 65 and 75%, respectively, was achieved after 50h. Carbon tetrachloride was the best solvent for solanidine extraction from the plant materials. The optimum ratio of plant material to carbon tetrachloride for the isolation of solanidine was 1:8 w/v for both extraction cycles, ensuring a yield of solanidine of approximately 55 and 65% from haulm and tuber sprouts, respectively, after 30 min.     

The degree of starch phosphorylation as influenced by phosphate deprivation of potato (Solanum tuberosum L.) plants

Summary The levels of starch phosphorylation in potato tubers were investigated in relation to fertilization with phosphorus (P) of field-grown and greenhouse-grown plants. The field-grown plants received 0, 15 or 30 kg P ha⁻¹. Starch from plants grown without P-fertilizer contained 15.6 nmol P (mg starch)⁻¹ whereas starch from plants grown with 30 kg P ha⁻¹ contained 20.6 nmol P (mg starch)⁻¹. The greenhouse-grown plants were cultured in inert media and received nutrient solutions containing 0, 3, 12 or 24 mg P l⁻¹, respectively. Plants grown with no P-fertilizer produced tuber starch with phosphorylation levels reduced to approximately 30% of the level found in plants grown with an ample supply of P. Thus, the level of starch phosphorylation can be modified by limiting the P-supply through the root system. Application of foliar P-fertilizer to the greenhouse-grown plants had no significant effect on the phosphorylation of the tuber starch.     

Performance of potato (Solanum tuberosum L.) in three tropical soil families as influenced by their temperature regimes

Potato experiments (cv. Kennebec) were conducted in three tropical soil families as part of a program to determine crop production potential and land capabilities of a network of tropical soil families. Good tuber yields resulted from matching the requirements of the potato crop to land characteristics. An average yield of 32,000 kg/ha was obtained in the thixotropic, isothermic soil family of Hydric Dystrandepts in Hawaii. The results of this study indicate that with optimum plant protection year-round potato production is possible in this family of Hydric Dystrandepts under rainfed conditions. Yields of irrigated plots in the clayey, kaolinitic, isohyperthermic soil family of Tropeptic Eutrustox were 36,000 kg/ha in the winter and 25,000 kg/ ha in the summer. The results indicate that winter temperatures are nearly isothermic, and are thus suitable for potato production, in an isohyperthermic Tropeptic Eutrustox of Hawaii. No yields were obtained from plantings in the clayey, kaolinitic, isohyperthermic soil family of Typic Paleudults in Indonesia and the Philippines. Tuberization did not occur in the warm and moist environment of the Typic Paleudults. Mismatch between the temperature requirements of the potato crop and the soil temperature regime of Typic Paleudults resulted in no potatoes.     

High temperature storage of potato (Solanum tuberosum L.) for processing — a feasibility study

Tubers of three potato cultivars were stored at room temperature (20–39°C, 30–75% RH), under an insulated storage run on passive evaporative cooling (16–30°C, 70–90% RH) and a refrigerated storage (2–4°C, 90–95% RH) for 14 weeks and studied periodically for storage losses, reducing sugar content and dry matter percent of tubers, in order to explore the possibility of storing potatoes for processing at higher temperatures. Physiological losses in tubers remained less than 10% until 12 weeks of storage under evaporatively cooled storage. Reducing sugar contents increased by only 52.4–242.1% in tubers stored in evaporatively cooled storage as compared to 90.5–484.2% increase in tubers stored in refrigerated storage until 14 weeks. Potatoes stored in evaporatively cooled store were more suitable for processing into chips and french fries due to lower physiological losses and lower reducing sugar content of tubers.     

栽培稻抗旱性研究的现状与策略

 水资源短缺正成为制约我国农业发展的重要因素。培育抗旱的栽培稻品种并实现水稻旱作，不但可在很大程度上节约水资源，而且有利于增产稳产，节约能源和减少环境污染。抗旱性包括逃旱性、避旱性、耐旱性和复原抗旱性。形态生理学的研究揭示出大量的与栽培稻抗旱性有关的形态特征和生理特性，如根系和叶片性状、生育期、渗透调节、脱落酸含量与栽培稻抗旱性密切相关，且已利用分子标记对上述性状进行了基因定位（QTL）研究。旱稻品种改良也已取得重大进展。在进行抗旱品种改良的基础上，通过引进相应的栽培技术，节水种植，实现水稻旱作，并达到稳产与增产的目的，是抗旱性研究的战略目标。在增产、稳产和优质的前提下，以培育耐旱性极强的水稻（或旱稻）为中心，建立有代表性的抗旱性研究基地, 进一步加强稻属抗旱基因资源的发掘和创新、抗旱生理学和遗传学的研究、利用现代生物技术实现不同物种间抗旱基因的转移、建立节水种植栽培技术新体系是目前抗旱性研究的主要内容。