Database derived microsatellite markers (SSRs) for cultivar differentiation in <Emphasis Type="Italic">Brassica oleracea</Emphasis>

Fifty-nine Brassica oleracea cultivars, belonging to five botanical varieties, were evaluated for microsatellite (SSR) polymorphisms using 11 database sequence derived primer pairs. The cultivars represented 12 broccoli (Brassica oleracea var. italica), ten Brussels sprouts (B. o. var. gemmifera), 21 cabbage (B. o. var. capitata, including the groups white and red cabbage), six savoy cabbage (B. o. var. sabauda), and ten cauliflower (B. o. var. botrytis) cultivars from 13 seed suppliers. The 11 primer pairs amplified in total 47 fragments, and differentiated 51 of the cultivars, whereas the remaining eight cultivars were differentiated from the rest in four inseparable pairs. All SSR markers, except one, produced a polymorphic information content (PIC value) of 0.5 or above. The average diversity for all markers within the tested material was 0.64. There was no major difference in the diversity within botanical varieties and groups. The cluster analysis and the resulting dendrogram showed that the cultivars tended to group within these taxonomic units. The present study substantiates the use of microsatellite markers as a powerful tool for cultivar differentiation and identification in vegetable brassicas.     

Cross-enhancement: enhanced biodegradation of isothiocyanates in soils previously treated with metham sodium

Rates of degradation of 2-propenyl isothiocyanate (PrITC), benzyl isothiocyanate (BeITC) and 2-phenylethyl isothiocyanate (2-PeITC) in a soil known to biodegrade methyl isothiocyanate (MITC) at an accelerated rate, but never previously exposed to the other ITCs, were higher (persistence in soil increased by 1150, 80 and 100%, respectively,) than in a similar non-degrading soil. The rate of degradation of the same three ITCs was significantly lower in sterilised (autoclaved) soils than in the degrading soil. These results indicate that the three ITCs are susceptible to enhanced cross-biodegradation in soils where enhanced biodegradation of MITC has been induced by use of metham sodium soil fumigant. When Brassica plant tissue containing sinigrin (2-propenyl glucosinolate) as the predominant glucosinolate (GSL) was added to the degrading soil, the amount of PrITC present after 24 h was significantly lower than in the non-degrading soil at the same amendment rates. The toxicity to an insect test organism of the PrITC produced from the biofumigant plant tissue was correlated with the concentration of PrITC measured in the two soils, with 67% more plant tissue required in the degrading soil to cause 100% mortality as in the non-degrading soil (3.0 vs 5.0 mg g⁻¹). The effectiveness of biofumigation using ITC-producing Brassica plants may be diminished in soil suffering from enhanced biodegradation of MITC.     

Differential responses of chickpea (Cicer arietinum L.) — Rhizobium combinations to saline soil conditions

Summary Chickpea cultivars (Cicer arietinum L.) and their symbiosis with specific strains of Rhizobium spp. were examined under salt stress. The growth of rhizobia declined with NaCl concentrations increasing from 0.01 to 2% (w : v). Two Rhizobium spp. strains (F-75 and KG 31) tolerated 1.5% NaCl. Of the 10 chickpea cultivars examined, only three (Pusa 312, Pusa 212, and Pusa 240) germinated at 1.5% NaCl. The chickpea — Rhizobium spp. symbiosis was examined in the field, with soil varying in salinity from electrical conductivity (EC) 4.5 to EC 5.2 dSm^-1, to identify combinations giving satisfactory yields. Significant interactions between strains and cultivars caused differential yields of nodules, dry matter, and grain. Four chickpea — Rhizobium spp. combinations, Pusa 240 and F-75 (660 kg ha^-1), Pusa 240 and IC 76 (440 kg ha^-1), Pusa 240 and KG 31 (390 kg ha^-1), and Pusa 312 and KG 31 (380 kg ha^-1), produced significantly higher grain yields in saline soil.     

Genetic variability in Turkmen populations of Pistacia vera L.

Seedlings of Pistacia vera L. developed from seeds of two separate populations in Turkmenistan, Kepele and Agachli, were evaluated for their growth potential and genetic polymorphism. Plant growth rate as well as random amplified polymorphic DNA (RAPD) analysis showed distinct differences between the two populations. In plant height growth rate, 17 Agachli accessions were 1.3 times higher on average than that of 10 accessions of Kepele (significant at p = 0.046) and 1.2 times higher for trunk diameter growth rate (p = 0.062). Cluster analysis divided most accessions into two main genetic groups according to their geographic origin. The Agachli group was further divided into two subgroups. One Kepele accession (K4), was genetically different from the rest and clustered on a separate outgroup. Two Agachli accessions (A12 and A17) were outside the two main populations clusters. Accessions K9 and K10 from Kepele were exceptional and were clustered in each of the two Agachli's subgroups, indicating a close genetic relationship between the two populations. In addition, high similarity values (0.58–1.00) and small genetic distances reflect plausible gene flow between Kepele and Agachli, which are 100 Km apart. Mantel test revealed significant relationship between the RAPD and the morphological traits matrices, pointing to the genetic basis for the measured differences in the growth rate. Growing the accessions on the same plot, under similar conditions enabled the evaluation of genotypic differences. The combination of morphological traits and molecular markers will further assist in preservation of genetic variability and cultivation of useful genotypes of P. vera L.     

Growth Characteristics of Tea Plants and Tea Fields in Japan

In 12th century, the Buddhist priest Eisai brought tea ( Camellia sinensis L.) seeds to Japan from China and now tea plants are cultivated all over Japan except in the Hokkaido and Tohoku districts. The quality (reflected in the price) of Japanese green tea is affected by the nitrogen content. Consequently in tea fields, for last three decades large amounts of fertilizer have been applied to produce high quality tea. As a result, problems such as acidification of soil have been caused. It is also known that the growth of tea plants is stimulated by the addition of aluminum (Al) under acidic conditions. In this keynote address, some problems caused by excess applications of fertilizer in tea fields and the growth characteristics of tea plants related to Al are presented.     

Molybdenum reserves of seed,and growth and N2 fixation by Phaseolus vulgaris L.

Summary Plants grown from seed with high (1.5–7.3 g Mo seed^-1) and low (0.07–1.4 g Mo seed^-1) Mo contents were grown in the presence and absence of Mo in growth media (perlite) or in a flowing-solution culture, in a controlled environment. Neither the high (1.5 g Mo seed^-1) nor the low (0.1 g Mo seed^-1) Mo content in seed from a small-seeded genotype (BAT 1297) was able to prevent Mo deficiency (reduced shoot, root and nodule dry weight, N₂ fixation and seed production) in growth media without an external supply of Mo, whereas both the high (7.3 g Mo seed^-1) and the low (0.07 g Mo seed^-1) contents in seed were able to prevent Mo deficiency in a large-seeded genotype (Canadian Wonder). Responses to Mo treatment by the Two genotypes were inconsistent between the growth media and solution culture experiments. Seed with a large Mo content (3.5 g Mo seed^-1) from the Canadian Wonder genotype was unable to prevent Mo deficiency (reduced shoot and nodule dry weight and N₂-fixation) in a solution culture without an external source of Mo, whereas both the large (1.7 g Mo seed^-1) and the small (0.13 g Mo seed^-1) contents in seed prevented a deficiency in BAT 1297. Growing plants from seed with a small Mo content, without additional Mo, reduced the seed Mo content by 83–85% and seed production by up to 38% in both genotypes. Changes in seed size and increases in shoot, root and nodule dry weight occurred, but varied with the genotype and growth conditions. These effects were also observed in some cases where plants were grown with additional Mo, demonstrating that the amount of Mo in the seed sown can influence plant nutrition irrespective of the external Mo supply. Nodule dry weight, total N content of shoots and seed production were improved by using seed with a small Mo content (1.64–3.57 g Mo seed^-1) on acid tropical soils in Northern Zambia. Plants of both the large- and small-seeded genotypes grown from seed with a small Mo content (<1.41 g Mo seed^-1) had a smaller nodule weight, accumulated less N and produced less seed. The viability of seed with a small Mo content was lower (germination up to 50% less) than that of seed with a large Mo content.     

Effect of encapsulated calcium carbide on dinitrogen,nitrous oxide,methane, and carbon dioxide emissions from flooded rice

Summary The efficiency of N use in flooded rice is usually low, chiefly due to gaseous losses. Emission of CH₄, a gas implicated in global warming, can also be substantial in flooded rice. In a greenhouse study, the nitrification inhibitor encapsulated calcium carbide (a slow-release source of acetylene) was added with 75, 150, and 225 mg of 75 atom % ¹⁵N urea-N to flooded pots containing 18-day-old rice (Oryza sativa L.) plants. Urea treatments without calcium carbide were included as controls. After the application of encapsulated calcium carbide, 3.6 g N₂, 12.4 g N₂O-N, and 3.6 mg CH₄ were emitted per pot in 30 days. Without calcium carbide, 3.0 mg N₂, 22.8 g N₂O-N, and 39.0 mg CH₄ per pot were emitted during the same period. The rate of N added had a positive effect on N₂ and N₂O emissions, but the effect on CH₄ emissions varied with time. Carbon dioxide emissions were lower with encapsulated calcium carbide than without. The use of encapsulated calcium carbide appears effective in eliminating N₂ losses, and in minimizing emissions of the greenhouse gases N₂O and CH₄ in flooded rice.     

Vanadium induced manganese toxicity in bush bean plants grown in solution culture

Seedlings of two bush bean cultivars (Phaseolus vulqaris L. cvs. Mn‐sensitive ‘Wonder Crop 2’ and Mn‐tolerant ‘Green Lord') were grown for 14 days in full strength Hoagland No. 2 nutrient solution containing 0.05 ‐ 2 mg L^‐1 of vanadium (V) as ammonium vanadate.

Increasing V concentration in the solution decreased total dry weight of both cultivars. Plant tops were stunted and leaf color became dark green at 1 ‐ 2 mg L^‐1 V, especially in ‘Green Lord’. Veinal necrosis similar to that of Mn toxicity was observed in the primary leaves of ‘Wonder Crop 2’ at 0.2 mg L^‐1 V or above, but not in those of ‘Green Lord’.

The V concentrations in the roots increased exponentially with increasing V concentration in the solution; however, V concentrations in the leaves and stems were not affected. The Mn concentrations in the primary leaves increased under the higher V treatment in ‘Wonder Crop 2'; but not in ‘Green Lord’. In contrast, Fe concentration in the leaves of ‘Wonder Crop 2’ decreased markedly with increasing V concentration in the solution. Enhanced Mn uptake and greater reduction of Fe uptake by ‘Wonder Crop 2’ may explain the incidence of V‐induced Mn toxicity.     

Geographic Pattern of Genetic Diversity Among 43 Ethiopian Mustard(Brassica carinata A. Braun) Accessions as Revealed by RAPD Analysis

As an oilseed crop, the cultivation of Ethiopian mustard (Brassica carinata) is restricted only to Ethiopia. Even though geographic diversity is a potent source of allelic diversity, the extent of genetic diversity among germplasm material of Ethiopian mustard from different countries has not been assessed. Forty-three accessions, comprising 29 accessions from eight different geographic regions of Ethiopia and 14 exotic accessions from Australia, Pakistan, Spain, and Zambia were analysed for their genetic diversity using random amplified polymorphic DNA (RAPD) technique. A set of 50 primers yielded a total of 275 polymorphic bands allowing an unequivocal separation of every Ethiopian mustard accession. The usefulness of the 50 RAPD primers in measuring heterozygousity and distinguishing accessions was variable such that polymorphic information content (PIC) varied from 0.05 to 0.40, band informativeness (BI) from 0.05 to 0.65 and primer resolving power (RP) from 0.15 to 6.83. Jaccard's similarity coefficients ranged from 0.44 to 0.87 indicating the presence of a high level of genetic diversity. On the average, Australian and Ethiopian accessions were the most similar while, Spanish and Zambian accessions were the most distant ones. Cluster analysis grouped the 43 accessions into four groups, which has quite a high fit (r = 0.80) to the original similarity matrix. With no prior molecular information, the RAPD technique detected large genetic diversity among the 43 accessions from five different countries and their grouping by dendrogram and principal coordinate analysis (PCoA) was inclined towards geographic differentiation of RAPD markers. Conversely, RAPD differentiation along geographic origin was not apparent within the Ethiopian accessions.     

Genetic relationships of Portuguese coles and other close relatedBrassica genotypes using nuclear RFLPs

Nuclear RFLPs were used to study the genetic relationships of 2 Portuguese coles, tronchuda cabbage and Galega kale, and 13 otherBrassica oleracea cultivars and 4 nine-chromosome wild brassicas. Cluster and principal coordinates analysis were conducted using RFLP data from 60 probe-enzyme combinations, detecting 277 polymorphic restriction fragments. The results showed that the accessions clustered in five groups: one with all theB. oleracea cultivars except kailan, and the four others isolated with kailan, wildB. oleracea, B. insularis andB. cretica, andB. montana, respectively. Kailan was separated from the other accessions ofB. oleracea cultivars and genetically close to the wildB. oleracea, that was clearly separated from the other nine-chromosome wild brassicas. In theB. oleracea cultivars 3 groupings were clearly individualized: i) including broccolis and cauliflower; ii) with a misture of kales and cabbages originally from Central-North Europe; iii) formed by Portuguese coles. These preliminary results suggest the existence of three major regions of domestication of B. oleracea in Europe: Italy, Central-North Europe and Portugal. Kailan or chinese kale seems to have evolved separately from the otherB. oleracea cultivars in Eastern Asia.