Marker-assisted optimization of an expert-based strategy for the acquisition of modern lettuce varieties to improve a genebank collection

To regularly improve the composition of the lettuce collection of the Centre for Genetic Resources, the Netherlands (CGN) with modern varieties, feedback from crop experts is used to select approximately 10% of the new material for incorporation in the collection. In the present study, assessments of six experts were compared to microsatellite data of 414 new varieties and 1408 existing accessions. Based on the microsatellite data, the extent to which the genetic diversity of the collection would be enriched (added value) was calculated for specific sets of new varieties. When individual assessments of experts were evaluated, the total added value of expert-based selections was not significantly higher compared to randomly chosen groups, except for a single expert. Unfamiliarity with new varieties was shown to be a crucial factor in the assessment of crop experts. According to the current acquisition protocol that seeks for consensus among experts, varieties are selected based on recommendations from at least three experts. This protocol also did not perform better than randomly chosen groups of new varieties. However, significantly better results were obtained with alternative protocols. It was concluded that breeding value was a more decisive criterion in the current acquisition protocol than maximal extension of the genetic diversity within the collection. A modified protocol addressing both commercial and diversity aspects was suggested in order to meet the demands of plant breeders as well as conservationists.     

我国植物生长调节剂限量标准与CAC限量标准的比对分析

本文概述了我国植物生长调节剂的限量标准与CAC限量标准的制定现状,并进行了对比分析。我国农药残留限量标准制定工作起步较晚,技术基础较为薄弱,与国际食品法典农残限量标准相比,还有较大差距。加快制定我国植物生长调节剂限量标准,推进CAC限量标准转化,有利于推动我国农产品出口,保证农产品质量安全。     

Adventitious shoot regeneration in a bioreactor system and EST-PCR based clonal fidelity in lowbush blueberry (Vaccinium angustifolium Ait.)

Adventitious shoots were regenerated from leaf explants of three lowbush blueberry (Vaccinium angustifolium Ait.) clones: ‘QB1’, ‘QB2’ and ‘PB1’ by culturing on a gelled basal medium (BM) with 2.3–4.5 μM thidiazuron (TDZ) for four weeks followed by in a bioreactor system containing the same liquid medium but with 1.2–2.3 μM TDZ for another four weeks. Young expanding basal leaf segments with the adaxial side touching the culture medium and maintained for two weeks in darkness, produced the best results. Callus development and shoot regeneration were genotype dependent. Adventitious shoots were elongated in the liquid BM with 1 μM zeatin and rooted on a three peat: two perlite (v/v) medium. Acclimatized plantlets were grown actively in the greenhouse with an apparent normal leaf and shoot morphology. Ten random ‘QB1’ regenerated plants were screened using 14 expressed sequence tag-polymerase chain reaction (EST-PCR) markers and showed similar monomorphic amplification profiles confirming clonal fidelity of in vitro-derived ‘QB1’ plants. Results obtained suggested the possibility of adventitious shoot regeneration and true-to-type lowbush blueberry micropropagation using a bioreactor system combined with gelled medium.     

Environmental effects on seed yield determination of irrigated peanut crops: Links with radiation use efficiency and crop growth rate

In Argentina, delayed sowing causes a decrease in seed yield and in radiation use efficiency (RUE) of peanut crops (Arachis hypogaea L.), but it is not known if RUE reduction is mainly due to reduced temperature during late reproductive stages or to a sink limitation promoted by decreased seed number in these conditions. We analyzed seed yield determination and RUE dynamics of two cultivars (Florman and ASEM) in four irrigated field experiments (Exp_n) grown at three sites and five contrasting sowing dates (between 17 October and 21 December) in three growing seasons. An additional field experiment was performed with widely spaced plants (i.e. with no interference among them) to evaluate the effect of peg removal on RUE and leaf carbon exchange rate (CER). Seasonal dynamics of mean air temperature and irradiance, biomass production (total and pods), and intercepted photosynthetically active radiation (IPAR) were followed. Seed yield and seed yield components (pod number, seeds per pod, seed number and seed weight) were determined at final harvest. Crop growth rate (CGR) and pod growth rate (PGR) were computed for growth phases of interest. RUE values for crops sown until 14 November were 1.89–1.98 g MJ⁻¹ IPAR, within the usual range. RUE decreased significantly for cv. Florman in the late sowing of Exp₁ (29 November) and for both cultivars in Exp₃ (21 December sowing). Across experiments, seed yield (4.5-fold variation relative to minimum) was strongly associated (r² = 0.87, P < 0.0001) with variations in seed number (3.5-fold variation relative to minimum), and to a lesser extent (r² ≤ 0.54, P ≤ 0.001) to variations in seed weight (1.9-fold variation relative to minimum). Seed number was positively related (P < 0.01) to CGR (r² = 0.66) and to PGR (r² = 0.72) during the R₃–R_6.5 phase (seed number determination window), while crop growth during the grain-filling phase (i.e. between R_6.5 and final harvest) was positively associated with grain number (r² = 0.80, P < 0.001). No association was found between RUE and mean air temperature, neither for the whole cycle nor for the phase between R_6.5 and final harvest, which showed the largest temperature variation (16.4–22.4 °C) across experiments. Use of mean minimum temperature records (range between 13.8 and 18.5 °C) did no improve the relationship. However, grain-filling phase RUE showed a positive (r² = 0.69, P = 0.003) linear response to seed number across experiments. This apparent sink limitation of source activity was consistent with the reduced RUE (from 2.73 to 1.42 g MJ⁻¹ IPAR) and reduced leaf CER at high irradiance (from ca. 30 to 15 μmol m⁻² s⁻¹) for plants subjected to 75% peg removal.     

Priming abiotic factors for optimal hybrid Cymbidium (Orchidaceae) PLB and callus induction,plantlet formation,and their subsequent cytogenetic stability analysis

Abiotic factors affect the induction of PLBs and callus in hybrid Cymbidium Twilight Moon ‘Day Light’. The initiation and proliferation of new PLBs and callus could be achieved on NAA and kinetin, supplemented at 0.1 mg l⁻¹ each, respectively, both within 45–60 days. Bacto agar was found to be the most suitable solidifying agent for PLB induction, although a higher shoot fresh weight was obtained on Gelrite; a pH 5.3 was optimal while pH 4.5 caused 100% explant necrosis; coconut water, when supplied at 10–20% (v/v) resulted in a significant increase in the number of PLBs formed per PLB segment (23.1 versus 14.6 in controls) while a massive (almost four-fold) increase in fresh top weight occurred when PLB explants were placed in liquid culture, as a result of hyperhydricity; Fe-EDTA (1 mg l⁻¹) and activated charcoal (1 g l⁻¹) stimulated total fresh weight and PLB formation in the presence of PGRs; PLB formation decreased but total fresh shoot weight increased with the addition of niacin or myo-inositol, both vitamins. Dark-grown PLB-induced plants were etiolated and had longer internodes and higher fresh weight than light-grown control plants at 45 μmol m⁻² s⁻¹; at 15 μmol m⁻² s⁻¹ shoots were slightly etiolated, fragile, and PLB formation was scarce. RAPD and mtDNA analysis of all resultant PLBs, callus or plants showed them to be genetically identical, with comparable chlorophyll contents. Despite the detection of cytological variation between different plant parts, little variation resulted from abiotic factor treatment.     

Regeneration and characterization of Swertia chirata Buch.-Ham. ex Wall. plants from immature seed cultures

First generation immature seeds (R₁) were collected from a field transferred micropropagated plant and seeds were induced to develop organogenic calli in Swertia chirata, a traditional revenue earning medicinal plant. Half strength MS medium with different growth regulators namely, BA, Kn (2.22–4.44 μM), NAA (2.69–5.37 μM), and 2.26 μM 2,4-D were used to induce callus and organogenesis. Isolated shoots produced roots either in the same medium or in presence of NAA (2.69–10.74 μM) or IBA (2.46–9.8 μM). Fully developed plantlets were successfully transplanted to soil and the fertile seed bearing plants developed. Occasionally plants derived from more than 56 weeks old calli showed some morphological variations. Such variations in regenerated plants is not reflected in their chromosomal constitution, with normal 2n = 26 chromosomes. Likewise, no variation was observed in DNA fingerprinting patterns among the short-term raised culture regenerants, which were morphologically similar to that of the donor plant illustrating their genetical uniformity and clonal fidelity. On the contrary, variation in DNA fingerprinting patterns was observed in long-term culture raised plants.     

Regeneration of different Cyclamen species via somatic embryogenesis from callus,suspension cultures and protoplasts

The present study is the first report of the establishment of embryogenic callus cultures from seedling tissue, the regeneration of plants via somatic embryogenesis and the development of a regeneration system from protoplast to plant, using three wild species of Cyclamen, Cyclamen graecum Link, Cyclamen mirabile Hildebrand, Cyclamen trochopteranthum Schwarz (syn. Cyclamen alpinum hort. Dammann ex Sprenger). The ability to form embryogenic callus and to regenerate via somatic embryogenesis was strongly genotype-dependent for each species. From 0.5 g callus, up to 1461 somatic embryos were formed in the case of C. mirabile. Culture media with different concentrations of plant growth regulators, CaCl₂ and activated charcoal significantly influenced embryo formation in this species. Up to 1.4 × 10⁶ protoplasts were isolated from 1 g of C. graecum cell suspension. Diverse growth responses of the protoplasts in two embedding agents, agarose and alginate, were observed for the different Cyclamen species. These specific growth characteristics could be used as a selection marker for future fusion experiments. From both protoplast culture systems, somatic embryos were regenerated, grown to plantlets and acclimatised to greenhouse conditions.     

植物生长调节剂对棉花生育的调控及产量效应

通过对植物生长棉花上使用方法的研究,结果表明,生长素和缩节胺对棉花的生育及产量有显著影响,ＩＡＡ能促进棉株生长,ＤＰＣ则能有效抑制棉株生长,二者应用方法得当则能使棉花增产。     

我国板栗化学调节研究进展

从应用植物生长调节剂和与营养生理有关的多种化学物质来调节板栗生长发育过程中的物质代谢和生理机能的角度,综述了我国近３０年来化学调节在调控板栗花性别分化、矫治空苞、增强结实性、提高嫩枝扦插和嫁接成活率、调节种子发芽、改善坚果贮藏性能等多方面的研究新成果,并对我国板栗化学调节研究现状和今后的主要研究方向进行了讨论。     

钙制剂及生长调节剂处理对草莓果实品质与植株生长的影响

以草莓(Fragaria ananassa Duchesne)品种丰香(F.ananassa cv.Toyonoka)和章姬(F.ananassa cv.Akihime)为试材,探讨了有机钙制剂浸果、2种植物生长调节剂喷施植株后对果实品质与贮藏性、植株生长及产量的影响.结果表明,不同钙处理能不同程度的延长草莓果实贮藏期,提高果实中可溶性固形物含量和糖酸比,降低含酸量.2种植物生长调节剂喷施对增加植株叶片数、花序数和株展直径也有显著的促进作用.