The embryogenic potential of rice cell suspensions affects their recovery following cryogenic storage

Summary The rates of recovery from cryogenic storage of suspension cultures of the Japonica rice cultivar Taipei 309, as determined by the reduction of triphenyl tetrazolium chloride and cell regrowth, were significantly influenced by the embryogenic potential of the non-frozen cultures.     

Transient gene expression in transformed banana (Musa cv. Bluggoe) protoplasts and embryogenic cell suspensions

Summary In order to introduce currently-available genes with agronomical value into banana, two genetic transformation protocols have been optimized.Firstly, regenerable protoplasts isolated from embryogenic cell suspensions of the cultivar Bluggoe have been used for the introduction of several chimaeric uidA gene constructs by electroporation. With the inclusion of polyethylene glycol and heat shock, the frequency of transiently expressing protoplasts reached 1.8% as shown by an in situ -glucuronidase assay. A duplicated 35S promoter with an alfalfa mosaic virus leader sequence (pBI-426) induced the highest expression rate among the constructs tested.Embryogenic cell suspensions of cv. Bluggoe have also been bombarded with accelerated particles coated with a high expression uidA gene construct (pEmuGN) using a biolistic gun. After a partial optimization of the procedure, transient GUS assays reproducibly demonstrated the presence of 400 blue foci in 30 l of settled cell volume (approximately 25 mg cells). Selection and characterization of antibiotic-resistant transformed cultures is in progress.Abbreviations AMV alfalfa mosaic virus - GUS -glucuronidase - TGE transient GUS expression - uidA gene for -glucuronidase     

The potential of ripening mutants for extending the storage life of the tomato fruit

Summary The effect of the fruit ripening mutants rin, gr, nor and Nr on storage life and pigmentation was investigated in homozygous material, in heterozygous F₁ combinations between the mutants with the colour mutant hp and with the normal cv. Kewalo. Crosses with nor showed a 3-to 5-fold increase in storage life in comparison with the normal cv. or with hp. Maximum pigmentation of the fruits of crosses with nor was pale-red with vineripened fruit and pink with fruit harvested at the breaker stage and ripened on the shelf. The ripening inhibitory effect of rin in the different F₁ combinations was less pronounced than that of nor, and the colour of the fruits was improved. Fruits of the F₁ cross between rin and nor showed greatly improved storage life and developed pink or pale red colour. Most heterozygotes with hp showed improved pigmentation. Problems anticipated in utilizing ripening mutants in breeding for improved keeping quality are discussed.     

Seed storage potential of population varieties and hybrid varieties and their breeding components in rye (Secale cereale L.)*

Seeds of population varieties, hybrid varieties, cytogenetic male sterility (CMS) single cross lines and CMS inbred lines of rye (Secale cereale L.) were stored to determine the respective rates of germination loss with a view to their storage potential. The seeds were stored under controlled conditions at a seed moisture content of 14% and a temperature of 30°C for periods of up to 80 days. The storage potential decreased in the order: hybrid varieties > population varieties > CMS single cross lines > CMS inbred lines. However, the rates of germination loss showed no differences within the respective categories. The inferences drawn for seed storage potential hold for seed vigour potential.     

The recovery of benthos following the impact of low oxygen content in the German Bight

The oxygen deficiency in the German Bight and in Danish waters 1981–1983 with ensuing benthos mortality was the reason for studying the development and re-establishment of the macrofauna in the following years. These years, from 1984–1987, exhibited more favourable oxygen conditions.The macrofauna of this region with its predominantly sandy substrate belongs to the Tellina fabula community. It is dominated by regular seasonal and ephemeral species such as Spio filicornis, Phoronis spec., Spiophanes bombyx and Lanice conchilega.In 1983, a year with exceptionally low oxygen content in bottom waters (< 1 mg O₂ dm⁻³), the macrofauna showed, in some parts of the investigated area, as reduction of approx. 30–50% in species numbers. Concurrently, the individual numbers of the remaining species were reduced. Beginning in 1984, a rapid recovery of benthic communities was observed. By 1986, biomass as well as species- and individual numbers rose to values similar to those determined by other authors in earlier surveys of the German Bight. In particular, juvenile Echinocardium cordatum and crustaceans have been observed since 1984 in larger numbers.     

Comparison of eating quality and seed storage protein among Korean rice landraces

Improving eating quality and nutrition is one of the most important objectives in rice breeding program. Palatability factors and seed protein patterns of 69 Korean rice landraces were compared in this study. Of seven palatability factors, setback viscosity (SBV) had the largest variance, ranging from -144 to 45. Water content (WC) had the lowest variance, ranging from 11.0 to 13.0. In correlation analysis, eating quality was positively correlated with all palatability factors except gelatinization temperature (GT). In principal component analyses (PCA), the first PC with Eigen value of 5.06 explained 42.2% of the total variance. Cool paste viscosity (CPV) was the variable that had the largest positive loading. The second PC with Eigen value of 2.09 explained an additional 17.4% of the total variance. SBV was a variable that had the highest negative loading. Peak viscosity (PKV) had positive variance between PC1 and PC2. The 69 Korean rice landraces were clustered into four groups based on physicochemical properties and palatability factors, with groups I and II showing higher EQ than other groups. SDS-PAGE analyses revealed five seed storage patterns in the 69 Korean rice landraces. Among them, 84% (58 landraces) had pattern I. These results indicate that it is possible to develop high palatability cultivars using Korean rice landraces. In addition, screening of landraces based on variation in seed storage protein profile using SDS-PAGE could be highly effective for the identification of valuable rice genetic resources.     

Field performance of embryogenic cell suspension-derived banana plants (Musa AAA, cv. Grande naine)

Growth and yield characteristics of two different clones of banana plants (Musa AAA cv. Grande naine) originating from four months old embryogenic cell suspensions were studied. These characteristics were compared with those plants produced by the conventional in vitro budding multiplication method. Two types of variants were observed during the acclimatization phase among 500 embryogenic cell suspension derived plants. The first type related to banana plants with `variegated or deformed leaves' were also observed in in vitro budding derived plants. The second type concerned `fasciated-leafed' plants. During the field growth, these two variant types produced plants morphologically similar to the other plants. Thus, none of the cell suspension derived plants exhibited off-type traits in the field. A Fisher block model was used to compare the field performances of the two clones produced through the two in vitro propagation techniques. The analysis of variance showed that there were no significant differences between the plants produced by either micropropagation techniques for the plant height and circumference, the length of the reference leaf, the number of nodal clusters of the inflorescence and of fruits, the bunch weight, the period of time between planting and flowering, and between planting and harvesting. This study showed that banana plants with an agronomical behaviour similar to those produced by the conventional in vitro budding method could be regenerated from embryogenic cell suspension. This revised version was published online in July 2006 with corrections to the Cover Date.     

杂交水稻及不育系种子安全越年贮存研究

该研究提出了利用低温仓库贮存杂交水稻及其不育系种子的理想入库月份和安全转库或停机时期,以利最大限度地降低贮存成本,认为高温季节种子出库应采取“预热”处理。同时指出,当种子水份低至11％左右时,可以在多种贮存条件下实现安全越年贮存。     

A novel procedure for raising rice seedlings and its potential application for mass-screening of rice strains for salt tolerance

Summary A soilless culture system is described whereby all the necessary steps of raising rice seedlings, including seeding, surface-sterilization, germination and growing of seedlings, can be conveniently achieved within a small plastic container. The system is especially suited for experiments with massive number of entries and can e.g. be used for screening of rice genotypes for salt tolerance.     

Effect of rice flour coating on 2-acetyl-1-pyrroline and n-hexanal in brown rice cv. Jao Hom Supanburi during storage

The effect of coating brown rice with flour gel on the amount 2-acetyl-1-pyrroline (2AP) and n-hexanal was investigated. The brown rice was stored in different packaging and the quality of rice was monitored during storage. In all coating treatments, an inverse relationship was observed with the amount of 2AP decreasing as storage time increased. Coating brown rice has the effect of decreasing the amount of 2AP while obstructing the formation of n-hexanal. Vacuum packaging brown rice with laminated OPP/Al/LLDPE stabilizes both the amount of 2AP and n-hexanal. Color intensity of coated brown rice remained relatively unchanged during storage. Water activity of non-coated brown rice packed in OPP/Al/LLDPE was lowest.     

高原优质抗病滇型杂交粳稻滇杂32达到中国超级稻产量目标

云南农业大学稻作研究所选育的滇型杂交粳稻滇杂32，连续两年在同一生态区百亩示范片经专家现场验收，达到了中国超级稻产量目标。介绍了滇杂32及示范的基本情况，总结了“滇杂32”达到超级稻产量目标的栽培技术措施及产量结构形成。     

再论贵州杂交水稻超高产潜力

本文在广泛调查的基础上,经过汇总、筛选、归类及模型分析,将贵州当前主栽超高产杂交水稻品种分为穗数型、兼用型和大穗型3种类型,并建立了不同类型产量因素及互作项的回归模型,模型相关系数高,理论值与观测值之间的拟合误差小。围绕来自实践所建立的数学模型和所提出的关键性技术措施,对于挖掘贵州水稻超高产潜力,在理论和实践上均有重要意义。     

Transferability of rice SSR markers to Miscanthus sinensis, a potential biofuel crop

Miscanthus sinensis (M. sinensis) is a perennial C₄ photosynthesis grass, with high yield, high efficiency of water usage, low fertilizer requirement, tolerance to extreme environments, and is one of the plant species with good biofuel potential. Simple sequence repeat (SSR) markers are highly informative and widely used in plant genetic studies. In this study, 88 SSR primer pairs derived from the rice genome, including 47 EST-SSRs (eSSRs) and 41 genomic SSRs (gSSRs), were evaluated for cross-species transferability to M. sinensis. Forty-one SSR primer pairs in total could successfully amplify DNA fragments in M. sinensis, showing an overall transferability rate of 46.6 % between rice and M. sinensis. The transferability rate of eSSR (51.1 %) was higher than that of gSSR (41.5 %). A total of 140 SSR loci and 340 alleles in the set of rice and M. sinensis germplasm collections were detected. Nei’s gene diversity varied from 0 to 0.72 and averaged 0.35. Shannon’s information index varied from 0 to 1.49 and averaged 0.56. The observed heterozygosity ranged from 0 to 0.95 and averaged 0.08. Thirty-nine loci (27.86 %) were shown heterozygosity out of 140 SSR loci. A dendrogram based on genetic distance showed a significant geographic differentiation. Our results indicated that 46.6% of the rice SSR markers are transferable to M. sinensis, and are useful for germplasm evaluation and genetic analysis in M. sinensis.     

Evaluation of maize varieties for their potential as breeding populations

Summary A 7-variety diallel of synthetic varieties that have not had selection for yield improvement and a 10-variety diallel of synthetic varieties that either resulted from recurrent selection for yield improvement or from the introgression of exotic germ plasm into adapted varieties were evaluated in six environments for yield and five other agronomic traits. The specific objective was to determine the relative potential of the synthetic varieties as germ plasm sources for breeding programs.Recurrent selection improved population yield in BSSS CO, BSK CO, and Alph CO in the varieties and also in crosses with other varieties. BSSS(R)C6 and BSSS(HT)C7 yielded 11.4% and 16.1% more than BSSS CO, and the variety crosses of BSSS(R)C6 and BSSS(HT)C7 yielded 21.6% and 22.0% more than the variety crosses of BSSS CO. Recurrent selection also improved stalk-lodging resistance for BSSS(R)C6 and BSSS(HT)C7, but root lodging for BSSS(HT)C7 was significantly higher. BS15 had 61.0% higher yields than Alph CO, with 9.3% less stalk lodging. Average heterosis of the 10-variety diallel was 1120 kg/ha (19.6%) and ranged from 800 kg/ha (13.7%) for BSK(S)C5 to 1770 kg/ha (39.4%) for BS12(HI)C5. The heterosis expressed among individual variety crosses ranged from 4.3% for BSK(S)C5 x BSTE(FR)C1 to 37.6% for BSSS(R)C6 x BS12(HI)C5, which approached the yield of the two highest yielding single-cross checks.In the 7-variety diallel of unselected varieties, BSTE CO and Late Rootworm Synthetic were superior as varieties and in crosses for yield and stalk quality. Average heterosis for the 7-variety diallel was 950 kg/ha (18.5%). Stalk lodging was important in the performance of varieties with poor stalk quality.Although recurrent selection improved yield, development of superior breeding populations also will require selection for general agronomic performance. The performance of BS16 and the yields of BSTL and Teozea and their crosses suggest that exotic germ plasm should receive greater attention.Contribution from the Agricultural Research Service, U.S. Department of Agriculture, and Journal Paper No. J-8096 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50010. Project No. 1897.     

A comparison of microtubers and field-grown tubers of potato (Solanum tuberosum L.) for hexoses, sucrose and their ratios following postharvest cold storage

Cold-induced sweetening (CIS) is a significant postharvest problem in processing potato (Solanum tuberosum L.) tubers. A rise in hexose sugar levels during cold storage results in a brown, bitter tasting and unmarketable product. We tested if potato microtubers (MicroT) can undergo CIS and if this corresponds to the CIS response in field-grown tubers (FieldT) with the hope of fast-tracking breeding programmes using a MicroT system. Using MicroT from potato genotypes representing a range of CIS response levels we have demonstrated that MicroT undergo CIS more rapidly than FieldT. Correlations of glucose:sucrose and hexose:sucrose ratios were highly significant between the two tuber types after cold treatment and these ratios are known to be good predictors of invertase activity, a key regulator of CIS. Correlations of individual sugars were non-significant before and after postharvest cold treatment.     

Fixation and release of ammonium in flooded rice soils as affected by redox potential

In pot experiments with two typical paddy soils, we studied the significance of ammonium fixation under waterlogged conditions and the availability of this N fraction for wetland rice. Special attention was given to the influence of redox potential (E_h) on the fixation and release of NH⁺₄, since the E_h has been shown to affect the charge conditions of certain expandable clay minerals and may alter their cation exchange capacity (CEC). The results demonstrate that ammonium formed by mineralization after flooding was converted, to a substantial degree, into a non-exchangeable form when sufficient amounts of expandable 2:1 minerals were present. The newly fixed NH⁺₄ was protected from N losses via nitrification-denitrification processes, which may occur, especially during the drying and rewetting of the soil, but was completely available to the following rice crop. The release of fixed NH⁺₄ was highest in the rhizosphere of rice plants (where the E_h was greatly increased by the O₂ secretion of the roots) and decreased with growing distance from the roots. Correlations between the E_h and the concentration of non-exchangeable NH⁺₄ indicate that fixation and mobilization of ammonium are strongly influenced by the redox potential in paddy soils.     

水稻包衣种子的生产

种衣剂技术是农业部“九五”期间重点推广的十大农业技术增产措施之一 ,是实施种子工程建设的重要内容。但水稻种子包衣应用推广较旱作种子晚 ,主要是水稻的包衣剂技术要求高 ,到二十世纪 90年代中期才开发成功较稳定的剂型 ,我市从1997年引进应用 ,效果良好。包衣种子不仅具有防治病害 ,提高出苗率 ,促进幼苗生长发育 ,增加产量作用 ,而且还可提高种子质量 ,节省种子 ,减少用工 ,以其投入小收效快 ,受到广大群众的欢迎。目前 ,我市每年推广包衣种子 2 1万公斤 (杂交稻种子 ) ,包衣率达 80 %以上 ,每年还为其它县市加工包衣种子 6万余公斤。…