Association of bud and anther morphology with developmental stages of the male gametophyte of melon (Cucumis melo L.).

Correlations between the morphological features of f lower buds and the developmental stages of the male gametophyte are of great practical interest as a reliable marker that accelerates and simplif ies the selection of appropriate plant material for isolated microspore culture. Microspore culture enables one to quickly obtain many pure lines of different vegetable crops, but it has not yet been widely applied in the melon (Cucumis melo L.). To successfully apply this technique in a new culture, one has to optimize many of its elements: f irst, f ind the biological markers for selecting the f lower buds containing the microspores of certain development stages. The paper presents the results of research estimating the correlations between the length and diameter of the f lower buds, the length of the visual part of the corolla, the length of the anthers and the development stages of the male gametophyte in the F1 hybrid of the Kim Hong Ngoc melon. The strongest correlation (CC = 0.885) was found for the f lower bed diameter and a strong correlation (CC = 0.880), for the bud length. The corolla's visual part was a less reliable morphological feature, and the anther's length should not be used as a parameter to predict the developmental stages of the melon's male gametophyte. It was also found that one anther could contain the microspores and pollen grains of different developmental stages. In the f lower buds less than 4 mm in length and 1.51 ± 0.02 mm in diameter prevailed tetrads, and in the buds 4.0-4.9 mm in length and 2.30 ± 0.02 mm in diameter, early microspores. The microspores of a middle stage of development prevailed in the f lower buds 5.0-5.9 mm in length and 2.32 ± 0.00 mm in diameter; mid and late vacuolated microspores, in the buds 6.0-8.9 mm in length and 2.96 ± 0.37 mm in diameter; and two-celled pollen, in the buds more than 9 mm in length and more than 3.97 ± 0.34 mm in diameter.

Methodological approaches for producing doubled haploids in sugar beet and red beet (Beta vulgaris L.).

The in vitro production of doubled haploids is a biotechnological path of an accelerated development of parental lines in F1-hybrid breeding programs. Unlike the traditional inbreeding method requiring 5 to 6 generations to reach a suf-f icient homozygosity of lines, the number of generations to produce pure lines of beet by haploid technologies is reduced to 2. The production of doubled haploids by gynogenesis is the most common biotechnological approach in sugar and red beets. Protocols for the production of doubled haploids for B. vulgaris species are few and have been developed mainly for sugar beets. There are no protocols for the production of doubled haploids for red beet (B. vulgaris convar. esculenta Salisb.), and the protocols developed for sugar beet (B. vulgaris convar. saccharifera Alef.) are ineffective for red beet, even though these two crops belong to the same species. The greatest success has been achieved in the production of doubled haploids by gynogenesis through isolated ovule culture, especially in sugar beet. Studies on the production of doubled haploids by androgenesis were actively carried out in the 1970s and 1980s and did not lead to the production of regenerated plants. However, at present, there is renewed interest among researchers in this approach, and scientists in different countries are conducting studies of Beta vulgaris androgenesis through isolated microspore culture. This article provides an overview of studies devoted to the production of doubled haploids, addressing the main problems of doubled haploid technologies, and methods to increase the frequency of embryogenesis and doubled haploid plant formation in B. vulgaris crops.

Decontamination of seawater from 137Cs and 90Sr radionuclides using inorganic sorbents.

In this work, we have studied sorption of 137Сs and 90Sr radionuclides from seawater under batch conditions by ferrocyanide sorbents based on hydrated titanium and zirconium dioxides (Т-35, NPF-HTD), clinoptilolite and glauconite (NPF-GL, NPF-CL) natural aluminosilicates, zirconium phosphate (T-3A), modified hydrated titanium dioxide (T-3K) as well as by manganese dioxide based on hydrated titanium dioxide (MD-HTD). Isotherms of sorption and dependences of cesium distribution coefficients on salt content and calcium concentration were obtained. Distribution coefficients of cesium and strontium were calculated. Stability of spent sorbents against radionuclides leaching was studied in from the point of view of their further treatment. The NPF-GL and NPF-HTD sorbents are recommended for treatment of seawater-based liquid radioactive waste with various salinity; these sorbents possess high distribution coefficients of cesium 104 and 105 ml/g even at the salinity of waste as high as 100 g L-1. Distribution coefficients of strontium from seawater were (1.0-1.9)·102 ml/g for all sorbents that is conditioned by the presence of colloidal species of strontium (34 ± 7%) in the simulated seawater. Capacities of the sorbents for strontium varied within 200-310 mg/g. The sorbents strongly retain adsorbed radionuclides: the total percentage of leaching for 28 days was 4.4%, 2.2% and 3.1% for 137Cs leaching from the NPF-HTD, T-35 and T-3A sorbents respectively and 10.7% for 90Sr leaching from the NPF-CL sorbent.

Radionuclides: Accumulation and Transport in Plants.

Application of radioactive elements or radionuclides for anthropogenic use is a widespread phenomenon nowadays. Radionuclides undergo radioactive decays releasing ionizing radiation like gamma ray(s) and/or alpha or beta particles that can displace electrons in the living matter (like in DNA) and disturb its function. Radionuclides are highly hazardous pollutants of considerable impact on the environment, food chain and human health. Cleaning up of the contaminated environment through plants is a promising technology where the rhizosphere may play an important role. Plants belonging to the families of Brassicaceae, Papilionaceae, Caryophyllaceae, Poaceae, and Asteraceae are most important in this respect and offer the largest potential for heavy metal phytoremediation. Plants like Lactuca sativa L., Silybum marianum Gaertn., Centaurea cyanus L., Carthamus tinctorius L., Helianthus annuus and H. tuberosus are also important plants for heavy metal phytoremediation. However, transfer factors (TF) of radionuclide from soil/water to plant ([Radionuclide]plant/[Radionuclide]soil) vary widely in different plants. Rhizosphere, rhizobacteria and varied metal transporters like NRAMP, ZIP families CDF, ATPases (HMAs) family like P1B-ATPases, are involved in the radio-phytoremediation processes. This review will discuss recent advancements and potential application of plants for radionuclide removal from the environment.

Returning land contaminated as a result of radiation accidents to farming use.

An assessment is given of the possibility of sorbents based on natural aluminosilicates (glauconite and clinoptilolite) being used for remediation of radioactively contaminated land with the aim of returning it to farming use. A comparative study of selectivity and reversibility of radiocaesium and radiostrontium sorption by natural aluminosilicates as well as by modified ferrocyanide sorbents based on these aluminosilicates was made. It was found that surface modification of aluminosilicates by ferrocyanides increases the selectivity of synthesized sorbents to caesium by 100-1000 times, increases sorption capacity and makes caesium sorption almost irreversible, whereas, selectivity of these sorbents to strontium radionuclides remains approximately the same as for natural aluminosilicates. The caesium distribution coefficient for mixed nickel-potassium ferrocyanide on glauconite is 10((5.0±0.6)) L kg(-1), the static exchange capacity (SEC) is 63 mg g(-1); for mixed nickel-potassium ferrocyanide based on clinoptilolite caesium distribution coefficients in various concentration ranges are 10((7.0±1.0)), 10((5.7±0.4)) and 10((3.2±0.7)) L kg(-1), total SEC was 500 mg g(-1). Caesium leaching by various leaching solutions from saturated mixed nickel-potassium ferrocyanide based on clinoptilolite was lower than 2%; from saturated mixed nickel-potassium ferrocyanide based on glauconite it was 1.5-14.6%. Ferrocyanide sorbents, based on glauconite and clinoptilolite are recommended for remediation of land, contaminated by caesium as a result of the Fukushima accident in Japan. Use of these sorbents should decrease the transfer of caesium to agricultural vegetation up to a factor of 20.