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.     

Transformation of trifoliate orange with rice chitinase gene and the use of the transformed plant as a rootstock

RCC2, cDNA clone encoding rice class-I chitinase, was introduced into trifoliate orange (Poncirus trifoliata Raf.). Chitinase activity of the transformed plants was higher than that of the non-transformed plants. The introduced gene was not detected in the scions grafted onto the transformed plants. The effect of the introduction of foreign gene into rootstocks on the scions was discussed.     

Variations in body condition of green turtles (Chelonia mydas) in two nearby foraging grounds indicate their sensitivity to foraging habitats

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Comparison of cell wall components between Fragaria × ananassa and Fragaria chiloensis grown in Chile

Summary

Fruit firmness and cell wall composition were compared among five cultivars of F. × ananassa (‘Chandler’, ‘Seascape’, ‘Tudla’, ‘Hokowase’ and ‘Reiko’) and two land races of F. chiloensis (‘94BAU-1A’ and ‘97PUR-1A’) grown in central Chile. Fruits of F. chiloensis were smaller than those of F. × ananassa. Firmness of epidermal tissue did not differ significantly between F. × ananassa and F. chiloensis. Firmness of cortical tissue, however, was significantly lower in F. chiloensis than in F.× ananassa and as a result, difference in the firmness between epidermal and cortical tissues was significantly greater in F. chiloensis than in F. × ananassa. Calcium concentration was low in ‘Reiko’ and ‘Hokowase’ while high in the other varieties of F. × ananassa. F. chiloensis showed intermediate values between these two groups. Higher levels of total uronic acid and neutral sugars in cell wall fractions of F. chiloensis as compared with F. × ananassa were mainly due to its high concentration in the water soluble fraction. Total uronic acid in cell wall fraction was significantly higher in F. chiloensis than in F. × ananassa, mainly due to significantly higher concentrations in the water-soluble fraction. Non-cellulosic neutral sugars, especially arabinose in the water, CDTA, and Na₂CO₃-soluble fractions were significantly higher in F. chiloensis than in F. × ananassa. On the other hand, galactose in the CDTA-, Na₂CO₃-, and KOH-soluble fractions was significantly lower in F. chiloensis than in F. × ananassa. Moreover, cellulose concentration of F. chiloensis was also significantly lower than that of F. × ananassa. Results obtained from cell wall analysis suggest that softer cortex in F. chiloensis might be due to either lower cellulose content, higher solubilization rate of pectic substances, and/or compositional differences in the branching of neutral sugars.     

Effect of calcium supply on the physiology of fruit tissue in ‘Andesu’ netted melon

Summary

Fruit development and physiological traits were evaluated in ‘Andesu’ netted melon plants grown with and without calcium. Calcium exclusion accelerated softening, alcoholic fermentation and ethylene evolution of fruit compared with those supplied with calcium, but the opposite trend occurred with sucrose accumulation. A significant difference of calcium concentrations in the fruit between treatments was observed at the developing stage of the fruit (P<0.05), but the difference became smaller as fruit matured. In the mesocarp tissue from the basal hemisphere, calcium concentrations in the NaCl soluble fraction at ripe fruit stage differed significantly (P<0.05) between calcium treatments but no significant difference was detected in the inner mesocarp of the distal hemisphere. Calcium exclusion did not lead to the development of water-soaked symptoms in the mesocarp tissue of ripe fruit. Uronic acid concentrations in ionically bound pectin fraction did not differ between calcium treatments throughout fruit development. In covalently-bound pectin fraction, however, uronic acid concentration of ripe fruit was significantly lower in calcium-excluded plants than in calcium-supplied plants (P<0.05). Our results suggest that: first, accelerated fruit softening under calcium deficient conditions might result from promoted ethylene evolution rather than from the shortage of ionically-bound calcium in cell walls, second, calcium deficient condition does not necessarily lead to water-soaked symptoms in tissue of ‘Andesu’ melon fruit.     

Co-situs application of controlled-release fertilizers to alleviate iron chlorosis of paddy rice grown in calcareous soil

Abstract

Co-situs is the placement with one application of a sufficient amount of controlled-release fertilizer for an entire growing season at any site, together with seeds or seedlings, without causing fertilizer salt injury. An experiment was conducted to find an efficient method for ameliorating Fe deficiency in two rice cultivars (cv. Tsukinohikari and cv. Sasanishiki) grown in a calcareous soil (pH 9.2, CaCO₃ 384 g kg^?1), which was poor in organic matter (0.1 g kg^?1) and available Fe (3.0 μg g^?1 soil). The field treatments consisted of co-situs application of the following fertilizers: 1) controlled-release NPK fertilizer (CRF-NPK) containing no micronutrients; 2) controlled-release NPK fertilizer containing micronutrients (CRF-M1); and 3) controlled-release NPK fertilizer containing micronutrients (CRF-M2). The main difference between CRF-M1 and CRF-M2 was that the former had larger granules than the latter. All the fertilizers were placed in contact with the roots of rice seedlings at transplanting time. Plants in the CRF-M1 and CRF-M2 treatments had similar lengths, number of stems, leaf age, and leaf color (SPAR value) during the cultivation period. By contrast, plants from the CRF-NPK treatments grew poorly, showed severe chlorosis symptoms of Fe deficiency, and all died on 30 DAT. Plants of both cultivars accumulated more macroand micronutrients with the CRF-M2 treatment than with the CRF-M1 treatment. The grain yield of cv. Tsukinohikari was 0.0, 1,910, and 2,160 kg ha^?1 for the CRF-NPK, CRF-M1, and CRF-M2 treatments, respectively, and 0.0, 2,490, and 2,860 kg ha^?1 for the same treatments for cv. Nihonbare. Chlorosis due to iron deficiency was successfully ameliorated and world-average grain yields were obtained with the co-sites application of both controlled-release fertilizers.     

Time course study of aluminum-induced callose formation in barley roots as observed by digital microscopy and low-vacuum scanning electron microscopy

To clarify the mechanism(s) involved in the short-term inhibition of root elongation by AI, we monitored the morphological changes of barley roots by digital microscopy. Within 30 min after exposure to 37 µM AI, the surface of the root epidermis in the region of a distance of 1.5 mm from the root tip became rough and began to show signs of damage. After 38 min, callose was rapidly excreted from the junction between the root cap and the root epidermis, and formed a spherical lump approximately 60 µm in diameter. The fine structure of the callose deposits on the root surface was analyzed by low-vacuum scanning electron microscopy. After 50 min, there was a significant increase in the callose contents in the distal 0.6 mm part. At the same time, root elongation stopped completely. Fluorescence staining indicated that callose was localized on the surface of the cell elongation area (the elongation zone of primary roots and root hairs), but not on the surface of the meristem. The root growth reduction associated with AI treatment may be due to the use of sugar substrates for callose formation instead of cellulose formation.     

Increase in Iron and Zinc Concentrations in Rice Grains Via the Introduction of Barley Genes Involved in Phytosiderophore Synthesis

Increasing the iron (Fe) and zinc (Zn) concentrations of staple foods, such as rice, could solve Fe and Zn deficiencies, which are two of the most serious nutritional problems affecting humans. Mugineic acid family phytosiderophores (MAs) play a very important role in the uptake of Fe from the soil and Fe transport within the plant in graminaceous plants. To explore the possibility of MAs increasing the Fe concentration in grains, we cultivated three transgenic rice lines possessing barley genome fragments containing genes for MAs synthesis (i.e., HvNAS1, HvNAS1, and HvNAAT-A and HvNAAT-B or IDS3) in a paddy field with Andosol soils. Polished rice seeds with IDS3 inserts had up to 1.40 and 1.35 times higher Fe and Zn concentrations, respectively, compared to non-transgenic rice seeds. Enhanced MAs production due to the introduced barley genes is suggested to be effective for increasing Fe and Zn concentrations in rice grains.