Variation in Doubled Haploid Plants of Wheat Obtained through Wheat (Triticum aestivum) × Maize (Zea mays) Crosses

Variation was investigated in 110 doubled haploid (DH) lines of wheat derived from wheat × maize crosses. Field observation revealed visible variations in 15 DH2 lines such as extreme dwarfism, low seed fertility, alteration of spike type and stripes. Six agronomic traits, i.e., heading date, spike number/ plant, culm length, spike length, seed fertility and grain weight were statistically analyzed in the DH2 and DH3 generations. Out of the 88 DH2 lines/DH3 groups, 26 %/64 % showed significant differences from the parental variety in the means of one or more traits. Ranges of the DH3 lines were larger than those of the DH2 lines, except for spike number/plant. Furthermore, analyses of variance within and between DH lines showed the presence of heterogeneity/heterozygosity in the DH2 lines/plants. These results indicated the occurrence of gametoclonal variation in the DH lines. It is considered that most of the variations detected were due to the colchicine treatment rather than to the 2,4-D treatment or in vitro culture.     

The neuroexcitatory,convulsive and lethal effects of lindane analogs on Periplaneta americana (L.)

Lindane analogs, in which one or two chlorine atoms are replaced by various substituents, exhibit convulsive and lethal effects on Periplaneta americana (L.). Some analogs are as active as lindane. These effects are well related to the neuroexcitatory action which produces after-discharges in the central nervous system. Carbamate insecticides have potent convulsive and lethal effects on P. americana, which are also related to after-discharges produced in nerve cords. Convulsion caused by lindane analogs and carbamates is solely attributable to their neuroexcitatory effects on the nervous system, in spite of the difference in their ultimate modes of action.     

Transgenic cucumber expressing an endogenous class III chitinase gene has reduced symptoms from Botrytis cinerea

A class III chitinase gene (CHI2) is induced in cucumber plants (Cucumis sativa L.) in response to infection by pathogenic microorganisms. Infection of Botrytis cinerea, causal agent of gray mold disease on cucumber, also induces CHI2 expression. To investigate whether CHI2 is involved in resistance to gray mold disease, transgenic cucumber plants were produced to overexpress the CHI2 gene. One line was analyzed in detail in terms of disease resistance. The transgenic cucumber plant (CC2) constitutively expressed CHI2 and reduced the symptoms of B. cinerea for 4 days after inoculation compared with nontransgenic plants. However, this inhibitory effect was not absolute, and CC2 eventually developed serious disease symptoms. Chitinase activity of the crude extract from CC2 leaves was higher than that from nontransgenic plants. A high-molecular-weight fraction containing CHI2 from CC2 leaves had fungistatic activity against B. cinerea. Interestingly, the low-molecular-weight fraction from CC2 leaves with CHI2 removed also had fungistatic activity against B. cinerea. Not only the introduced chitinase activity but also the endogenous defense reactions activated by overexpression of CHI2 may be involved in the enhanced gray mold disease resistance in CC2.     

Evaluation of Cold Tolerance in NERICAs Compared with Japanese Standard Rice Varieties at the Reproductive Stage

New Rice for Africa (NERICA) is a general name for interspecific rice varieties derived from a cross between the high‐yielding Asian rice (Oryza sativa L.) between locally adapted African rice (Oryza glaberrima Steud.). Eight NERICAs were evaluated for cold tolerance (CT) at the reproductive stage and compared with their O. sativa parents and three Japanese standard rice varieties over 3 years. Cold tolerance was evaluated based on the filled grain ratio (FGR) after cold water irrigation. The FGR was greatly reduced by cold water irrigation. NERICA 1, 2 and 7 had higher FGR (51.9–57.9 %), while NERICA 6, 15 and 16 had lower FGR (6.2–14.5 %). NERICA 1, 2 and 7 were less affected by cold stress, with a 31 % mean reduction in FGR, while NERICA 6, 15 and 16 were greatly affected, with their FGRs being reduced by more than 80 %. NERICA 3 and 4 were moderately affected by cold stress, with about 45 % reduction rate in FGR. FGR significantly influenced the grain weights of the varieties with strong positive correlations (r = 0.83–0.91; P < 0.001), and thus, similar trends in grain weights were observed. Grain weights were reduced by 61.7–96.4 % under cold stress. NERICA 1, 2 and 7 showed significantly better performance than NERICA 3 and 4, while NERICA 6, 15 and 16 performed poorly under cold water irrigation. The Japanese varieties Koshihikari (very tolerant) and Ozora (moderately tolerant) were more affected by cold water irrigation than NERICA 1, 2 and 7. On the basis of the mean reduction rate (%) in FGR under cold stress, the varieties were classified as follows: NERICA 1, 2 and 7 as tolerant; NERICA 3 and 4 as moderately tolerant; and NERICA 6, 15 and 16 as susceptible to cold stress. However, NERICA 7 grain yields were lower under cold stress due to both greatly reduced number of panicles per plant and number of spikelets per panicle. Therefore, NERICA 1 and 2 are suitable candidates for production in the highland regions of East Africa and should be promoted for production.     

Effect of fungicide thiram on microbial communities of rice seed surface estimated by culture-dependent and culture-independent (PCR-RFLP) methods

Coating of rice seeds with fungicide Thiram improved the seed germination capability over a long period of time (11 weeks) under low temperature conditions (4 and 8°C), which simulated the sowing of rice seeds in the winter season (the farmer's slack season). To analyze the effect of Thiram on the community structure of microorganisms on the rice seed surface, culture-dependent and culture-independent (PCR-RFLP) methods were applied. PCR-RFLP patterns of 16S rDNA showed that the bacterial communities on the rice seed surface were different between coated and uncoated treatments under 8°C conditions, but that they were very similar under 4°C conditions. PCR-RFLP patterns of 18S rDNA revealed the remarkable effect of Thiram on the fungal community structure under both 4 and 8°C conditions. Although the fungal communities were quite different between coated and uncoated seeds at the beginning of incubation, the fungal communities on the coated seed surface became similar to those of uncoated seeds along with the duration of the incubation period. As the dominance percentage of Fusarium spp. among the isolates increased with the duration of the incubation period for both coated and uncoated seeds, Fusarium was considered to be a responsible for the poor germination of rice seeds that were sown in the winter season.     

Aggregates and gel network structure of globin hydrolysates

A gel with excellent functional properties was prepared successfully using the hydrolysates of globin. In the present study, the structures of intermediate aggregates and gel network were observed directly with an electronic microscope. It was shown clearly that the intermediate aggregates were in a thin rod shape with a length of 130--140 nm, which was in good accordance with the results of the light scattering obtained in a previous study. The diameter of intermediate aggregates was 4--5 nm. Each unit of the intermediate aggregate was composed of beta-chain and peptide beta-1 in a ratio of 1:1. Its molecular weight was 26922 Da, and it had a diameter of 4.1 nm. The thin rod-shaped aggregates were formed with units through the hydrophobic interaction. The length of intermediate aggregate was >30--33 times the diameter. Furthermore, the cross-linked structure formed by peptide alpha-1 and the thin rod-shaped aggregates was also confirmed by the photography of the electronic microscope. These results supported the model proposed in previous papers as proper to depict exactly the formation and structure of the gel network of globin hydrolysates.