松嫩平原不同株型玉米品种根系分布特征比较研究

采用土柱模拟栽培法与大田试验相结合的方法,对松嫩平原不同株型玉米的根系分布特征进行了比较。结果表明,平展型玉米和紧凑型玉米根干重最大值出现的时期不同,二者根干重分别在抽丝后15d和抽丝后30d时达到最大值,成熟时紧凑型玉米根干重比平展型高12．2％,二者根系垂直分布有明显的差异,在20cm以下的根干重比率,平展型玉米在19％以下,而紧凑型玉米高于23％,紧凑型玉米的深层根量较多,在深40～100cm土层内根干重比率比平展型高42．3％,二者的根系水平分布也不同,紧凑型玉米根系水平分布较集中,在距植株0～10cm水平范围内,根系分布比率比平展型玉米高9．6％,紧凑型玉米深层根量较多,水平分布集中,耐密植,是易获得高产的重要原因之一。     

Enhanced sensitivity to higher ozone in a pathogen-resistant tobacco cultivar

Investigations of the effects of elevated ozone (O(3)) on the virus-plant system were conducted to inform virus pathogen management strategies better. One susceptible cultivar of tobacco (Nicotiana tabacum L. cv. Yongding) and a resistant cultivar (Nicotiana tabacum L. cv. Vam) to Potato virus Y petiole necrosis strain (PVY(N)) infection were grown in open-top chambers under ambient and elevated O(3) concentrations. Above-ground biomass, foliage chlorophyll, nitrogen and total non-structural carbohydrate (TNCs), soluble protein, total amino acid (TAA) and nicotine content, and peroxidase (POD) activity were measured to estimate the effects of elevated O(3) on the impact of PVY(N) in the two cultivars. Results showed that under ambient O(3), the resistant cultivar possessed greater biomass and a lower C/N ratio after infection than the susceptible cultivar; however, under elevated O(3), the resistant cultivar lost its biomass advantage but maintained a lower C/N ratio. Variation of foliar POD activity could be explained as a resistance cost which was significantly correlated with biomass and C/N ratio of the tobacco cultivar. Chlorophyll content remained steady in the resistant cultivar but decreased significantly in the susceptible cultivar when stressors were applied. Foliar soluble protein and free amino acid content, which were related to resistance cost changes, are also discussed. This study indicated that a virus-resistant tobacco cultivar showed increased sensitivity to elevated O(3) compared to a virus-sensitive cultivar.     

Physiology of Rice Tungro Virus Disease: Involvement of Abscisic Acid-Like Substance in Susceptible Host-Virus Interactions

Stunting was severe in susceptible rice (Oryza saliva L.) cultivar ‘Taichung Native 1’ infected with tungro virus (RTV) compared to less-susceptible cultivar ‘IR 20’. The senescence of detached leaves of RTV-infected susceptible cultivar incubated in water in dark was accelerated compared to the healthy leaves as measured by the loss of total chlorophyll content. The transpiration rate of RTV-infected leaves of the susceptible cultivar was much lower than the healthy and RTV-infected leaves of the less-susceptible cultivar. Partially purified extracts obtained from RTV-infected leaves effectively inhibited GA-induced α-amylase synthesis in barley endosperms, and rice seedling growth, and they accelerated senescence of detached rice leaves. In all the three bibassays the ABA-like activity was significantly greater in the extracts from the RTV-infected susceptible cultivar than in extracts from the less-susceptible cultivar.     

不同穗型小麦品种分蘖发育的代谢基础研究

比较研究了大穗型和多穗型小麦品种的分薛发育特征及其代谢基础。结果表明,与多穗型品种相比,单株分蘖较少的大穗型品种分蘖期具有较低的IAA氧化酶（IAAO）活性、较高的IAA含量和较强的碳代谢活性。在分蘖的两极分化期,大穗型品种在碳、氮代谢和同化物分配方面存在较强的主茎优势,因此,其分蘖较难继续发育成穗。     

Influence of bacterial streak disease development on changes in phenolics,soluble amino acids and carbohydrates of rice leaves

The healthy leaves of rice cultivar ‘BJ 1’ resistant to bacterial leaf streak pathogen (Xanthomonas translucens f. sp.oryzicola) contained higher quantities of total phenolic compounds, reducing and nonreducing sugars than the susceptible cultivar ’IR 8’, while the leaves of cultivar ’IR 8’ possessed larger concentration of total soluble amino acids than the resistant cultivar ’BJ 1’. In the leaves of cultivar ‘BJ 1’, the disease development caused an initial decrease in the concentration of phenols followed by an increase at later stages. As a result of inoculation, soluble carbohydrates and amino acids generally decreased in the leaves of resistant cultivar ‘BJ 1’, in contrast to an increase in their concentration in the leaves of cultivar ‘IR 8’.     

Activities of enzymes involved in starch synthesis in wheat grains differing in starch content

This work was carried out to characterize starch accumulation and activities of key enzymes during grain filling in two wheat cultivars differing in starch content. The results showed that the starch accumulation rate (SAR) and activities of sucrose synthase, ADP-glucose pyrophosphorylase, soluble starch synthase, granule-bound starch synthase, and starch branching enzyme in the cultivar with a high starch content were significantly higher than those in the cultivar with a low starch content. The simulation with Richards’ equation showed that it was average starch accumulation rate but not active starch accumulation duration that determined starch accumulation. As compared with the cultivar with a low starch content, plants of the cultivar with a high starch content maintained the higher SAR and greater activities of related enzymes during mid and late grain filling stages. Consequently, the cultivar with a high starch content had advantages over that with a low starch content in terms of the amount of starch accumulation at mid and late grain filling stages.     

ABA Levels and Sensitivity in Developing Wheat Embryos of Sprouting Resistant and Susceptible Cultivars

A sprouting-resistant and a sprouting-susceptible wheat cultivar were utilized to examine the role of ABA levels and sensitivity responses in wheat embryonic germination. Endogenous embryonic ABA levels were measured in both cultivars throughout grain maturation utilizing a new and sensitive ABA immunoassay. Embryonic ABA levels of each cultivar were similar with the sprouting-susceptible cultivar having about a 25% lower ABA level than that of the sprouting-resistant cultivar. Larger differences between the cultivars were noted in sensitivity to ABA, as measured by capability of ABA to block embryonic germination. ABA inhibited embryonic germination much more effectively in the sprouting-resistant cultivar.     

A preference assay for quantifying symbiont choice in fungus-growing ants (Attini, Formicidae)

We describe a bioassay for the quantification of cultivar preference (symbiont choice) of fungus-growing ants. The bioassay simultaneously presents mycelium of multiple pure cultivar genotypes to worker ants in a cafeteria-style test arena, and preferred versus non-preferred cultivar genotypes can then be identified based on the ants’ quantifiable behavioral tendencies to convert any of the offered mycelium into a fungus garden. Under natural conditions, fungus-growing ants are likely to express such cultivar preferences when mutant cultivars arise in a garden, or when colonies acquire a novel cultivar from a neighboring colony to replace their resident cultivar. We show that workers from different nests of the fungus-growing ant Cyphomyrmex costatus exhibit repeatable preferences vis-à-vis specific cultivar genotypes. The identified preferred and rejected cultivars can then be used in a performance assay to test whether the ants prefer cultivar genotypes that are superior in enhancing colony fitness (measured, for example, as garden productivity or colony growth), as predicted by symbiont-choice theory. Received 24 February 2006; revised 23 June 2006; accepted 26 June 2006.     

Growth and cell wall properties of two wheat cultivars differing in their sensitivity to aluminum stress

The present study was conducted to investigate the cell wall properties in two wheat (Triticum aestivum L.) cultivars differing in their sensitivity to Al stress. Seedlings of Al-resistant, Inia66 and Al-sensitive, Kalyansona cultivars were grown in complete nutrient solutions for 4 days and then subjected to treatment solutions containing Al (0, 50 microM) in a 0.5 mM CaCl(2) solution at pH 4.5 for 24 h. Root elongation was inhibited greatly by the Al treatment in the Al-sensitive cultivar compared to the Al-resistant cultivar. The Al-resistant cultivar accumulated less amount of Al in the root apex than in the Al-sensitive cultivar. The contents of pectin and hemicellulose in roots were increased with Al stress, and this increase was more conspicuous in the Al-sensitive cultivar. The molecular mass of hemicellulosic polysaccharides was increased by the Al treatment in the Al-sensitive cultivar. The increase in the content of hemicellulose was attributed to increase in the contents of glucose, arabinose and xylose in neutral sugars. Aluminum treatment increased the contents of ferulic acid and p-coumaric acid especially in the Al-sensitive cultivar by increasing the activity of phenylalanine ammonia lyase (PAL, EC 4.3.1.5). Aluminum treatment markedly decreased the beta-glucanase activity in the Al-sensitive cultivar, but did not exert any effect in the Al-resistant cultivar. These results suggest that the modulation of the activity of beta-glucanase with Al stress may be involved in part in the alteration of the molecular mass of hemicellulosic polysaccharides in the Al-sensitive cultivar. The increase in the molecular mass of hemicellulosic polysaccharides and ferulic acid synthesis in the Al-sensitive cultivar with Al stress may induce the mechanical rigidity of the cell wall and inhibit the elongation of wheat roots.     

Physiology of Rice Tungro Virus Disease: Increased Cytokinin Activity in Tungro-Infected Rice Cultivars

Tungro virus infection decreased the chlorophyll content in the susceptible rice (Oryza sativa) cultivar ‘Taichung Native 1’, while it increased the pigment in the less-susceptible cultivar ‘IR 20’ during the later stages of infection. The virus was recovered from the infected susceptibile cultivar as early as 3 days after inoculation. Relatively low amounts of virus were recovered from the less-susceptible cultivar between 12 and 30 days after inoculation. The senescence of detached leaves of virus-infected less-susceptible cultivar incubated in water in darkness was considerably delayed compared to healthy leaves. The cytokinin activity in the extracts from inoculated less-susceptible cultivar was 69% higher than in the extracts from the healthy plants.     

Molybdenum efficiency in winter wheat cultivars as related to molybdenum uptake and distribution

The highly Mo efficient winter wheat cultivar 97003 yielded more than 90% and the low Mo efficient winter wheat cultivar 97014 less than 50% under Mo deficient conditions when compared to the Mo fertilizer treatment. The mechanism of Mo efficiency, molybdenum uptake and distribution in plant parts during all growth stages, was studied with these two cultivars when grown in an acid yellow-brown earth with no Mo (CK) and added Mo (+Mo) treatments. The results showed that accumulation of Mo and dry matter in shoots of cultivar 97003 was significantly higher than those of cultivar 97014 under CK through the entire growth period. Most of Mo was found accumulated in shoots after the stem elongation stage. Only low amount of Mo was accumulated during the cold winter until stem elongation stage where severe symptoms occurred in cultivar 97014 without Mo supply, while the Mo concentration of cultivar 97003 was significantly higher, thus improved its cold hardiness. Molybdenum concentrations in spikes and seeds were very low pointing to a low Mo mobility even under Mo sufficiency. However, much more Mo was distributed in the upper leaves at stem elongation stage, in spikes in heading stage, in seeds in maturity in cultivar 97003 than in cultivar 97014 under conditions of Mo deficiency. In the efficient cultivar, the Mo distribution ratios to the upper leaves and spikes were even higher without Mo supply, suggesting that a higher phloem mobility and thus a more efficient use of Mo under Mo deficiency stress. The ability of Mo uptake and phloem-mobility are discussed and it is suggested to be the important physiological basis of Mo efficiency.     

Genotypic differences in phosphorus efficiency of wheat

In an attempt to evaluate whether breeding and selection for high yielding capacity did change the P requirements of modern wheat cultivars, the response of two wheat cultivars to different levels of P supply was investigated. A traditional cultivar ("Peragis") and a modern cultivar ("Cosir") were cultivated in a C-loess low in available P and high in CaCO₃ in 120 cm high PVC pots. Shoot and root growth at different developmental stages was compared. The grain yield of the modern cultivar Cosir was higher at limiting and non-limiting P supply and, therefore, this cultivar can be considered as more P-efficient than the traditional cultivar. From the results it can be concluded that the main factors contributing to the higher P efficiency of the modern cultivar are (i) efficient use of assimilates for root growth characteristics which enhance P acquisition: smaller root diameter, and longer root hairs, (ii) efficient remobilization of P from vegetative plant organs to the grains, and (iii) lower P requirement for grain yield formation because of lower ear number per plant but higher grain number per ear.     

Peroxidase Activity in Leaves of Wheat Cultivars Differing in Resistance to Erysiphe graminis DC.

The peroxidase activities in leaves from resistant and susceptible cultivars of wheat infected and non-infected by Erysiphe graminis DC were studied. In non-infected wheat, soluble and ionic bound peroxidase activity level was found to be higher in the resistant cultivar than that in the one susceptible to Erysiphe graminis DC. After infecting wheat leaves with Erysiphe graminis DC a remarkable increase in the activity of soluble and ionic bound peroxidases was detected 5 days after inoculation only in the resistant cultivar. In the susceptible cultivar a high increase in the activity of the soluble and ionic bound peroxidases occurred only 15 days after inoculation. Using ion exchange chromatography four peroxidase fractions were obtained from infected susceptible and resistant cultivars as from non-infected ones. The fraction II in non-inoculated resistant cultivars was much higher than that in the susceptible one. This fraction increased after inoculation in both cases reaching a higher level in resistant cultivars. Fraction I was higher in the susceptible cultivar. Electrofocusing profiles of peroxidase from the susceptible and resistant cultivar differed from one another. New peroxidase bands after inoculation appeared only in the resistant cultivar.     

Transmission of 5R chromosomes via gametes and its influence on spring bread wheat somatic embryoidogenesis in vitro

Transmission of chromosomes 5R and 5A via gametes and its effect on somatic embryoidogenesis have been studied with the use of the model 5R(5A) substitution line L2837 = L503/Secale cereale L., cultivar Saratovskaya 5/L503, where L503 is a cultivar of spring bread wheat. It has been found that the frequencies of transmission of univalent chromosomes 5R and 5A determined in experiments on F1 reciprocal hybrids with cultivar Saratovskaya 29 do not reflect their frequencies in the self-pollinated offspring of F1 hybrids; the frequency of transmission of chromosomes 5R and 5A depends on the genotypes of both the recipient cultivar and the donor rye cultivar; and the 5R(5A) substitution in cultivar L503 significantly increases the parameters of somatic embryoidogenesis in vitro in explants from inflorescences.     

Morphological and genetic characteristics of leaf hairiness in wheat (Triticum aestivum L.) as analyzed by computer-aided phenotyping

Computer-aided image processing was used to study the morphology of leaf hairiness in the wheat cultivars Saratovskaya 29 and Golubka, as well as the introgressed strain 102/00i of the cultivar Rodina carrying the hairiness control gene introgressed from Aegilops speltoides. Morphological differences in leaf hairiness were detected and described in detail. The genetic control ofhairiness was studied in two cultivars (Golubka and Saratovskaya 29) with similar hairiness patterns. Crossing these cultivars with the cultivar Rodina showed a monogenic inheritance in the cultivar Golubka and a digenic inheritance in the cultivar Saratovskaya 29, which has a denser hairiness. In the strain 102/00i and the cultivar Golubka, the number of trichomes was positively correlated with their mean length. The cultivar Golubka was used as an example to study the effect of environmental conditions on the formation of hairiness. Plants of these cultivars were found to form more but shorter trichomes.     

主要产茶国茶树资源与红茶育种研究进展

茶树种质资源是茶树品种选育的材料基础。本文系统阐述了世界茶叶主产国在茶树资源收集、保存和鉴定评价方面所取得的进展,着重对红茶化学特性、红茶育种的研究成果进行论述。同时,对未来茶树育种的发展方向进行探讨。     

Transmission of 5R Chromosomes via Gametes and Its Influence on Spring Bread Wheat Somatic Embryoidogenesis in Vitro

Transmission of chromosomes 5R via gametes and its effect on somatic embryoidogenesis have been studied with the use of the model 5R(5A) substitution line L2837 = L503/Secale cereale L., cultivar Saratovskaya 5//L503, where L503 is a cultivar of spring bread wheat. It has been found that the frequencies of transmission of univalent chromosomes 5R and 5A determined in experiments on F₁ reciprocal hybrids with cultivar Saratovskaya 29 do not reflect their frequencies in the self-pollinated offspring of F₁ hybrids; the frequency of transmission of chromosomes 5R and 5A depends on the genotypes of both the recipient cultivar and the donor rye cultivar; and the 5R(5A) substitution in cultivar L503 significantly increases the parameters of somatic embryoidogenesis in vitro in explants from inflorescences.     

The effects of excess manganese on photosynthetic rate and concentration of chlorophyll in Triticum aestivum grown in solution culture

Manganese toxicity, which involves a broad array of physiological responses, has been identified as an important factor limiting plant growth on acid soils. In the experiments reported here, we examined the toxic effects of Mn on chlorophyll content, photosynthesis and respiration in two cultivars (Norquay and Columbus) of Triticum aestivum (wheat) which differ in tolerance of Mn. When grown over a range of concentrations of Mn (0–1 000 μ M ), the Mn-tolerant cultivar maintained higher rates of photosynthesis and respiration, and higher concentrations of chlorophyll a and chlorophyll b , than did the Mn-sensitive cultivar, despite greater accumulations of Mn in leaf tissues. After 5 days growth with 1 000 μ M Mn in solution, the photosynthetic rate fell to 25% of control in the sensitive cultivar and to only 75% of control in the tolerant cultivar. The concentration of chlorophyll a fell to 50% of control in the sensitive cultivar, but did not differ from control in the tolerant cultivar. Greater effects were seen on concentrations of chlorophyll b . which fell to 35% and 55% of control in the sensitive and tolerant cultivars, respectively. Rates of photosynthesis decreased in both cultivars as concentrations of chlorophyll decreased; however, the photosynthetic rate per unit chlorophyll remained constant or increased in the tolerant cultivar and decreased in the sensitive cultivar as concentrations of Mn in solution increased. Thus, in the sensitive cv. Columbus, Mn seemed to have a toxic effect on both chlorophyll content and photosynthesis per unit chlorophyll. In the tolerant cv. Norquay, the only clear effect of Mn was a reduction in chlorophyll content, although direct inhibition of photosynthesis could not be discounted.     

Alternaria Brassicae Induced Changes in the Activity of Cell Wall Degrading Enzymes in Leaves of Brassica Juncea

After inoculation of Brassica juncea leaves with Alternaria brassicae, activities of the cell wall degrading enzymes, polygalacturonase (EC 3.2.1.15) and cellulase (EC 3.2.1.4) decreased in leaf blight resistant cultivar RC-781 and increased in the susceptible cultivar Varuna upto 3 d. In the leaves of both the cultivars 11 poly-peptides were observed in the absence of A. brassicae inoculation. After inoculation in the resistant cultivar RC-781 there was no change in the polypeptide pattern, while in the susceptible cultivar Varuna, four polypeptides (43.7 to 58.8 kDa) disappeared only at 3^rd day after inoculation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Changes in Cell Wall-bound Phenolic Compounds and Lignin in Roots of Date Palm Cultivars Differing in Susceptibility to Fusarium oxysporum f. sp. albedinis

The roots of date palm contain four cell wall‐bound phenolic acids identified as p‐hydroxybenzoic, p‐coumaric, ferulic and sinapic acids. The ferulic acid represents the major phenolic compound since it constitutes 48.2–55.8% of cell wall‐bound phenolic acids. All these phenolic acids were present in the resistant cultivar (BSTN) and the susceptible cultivar (JHL). However, the pre‐infection contents of p‐coumaric, ferulic and sinapic acids were greater in the resistant cultivar than in the susceptible one. For the contents of p‐hydroxybenzoic acid, there was no significant difference between the resistant cultivar and the susceptible cultivar. Similarly, the pre‐infection contents of lignin were approximately equal for both cultivars. Inoculation of the date palm roots by Fusarium oxysporum f. sp. albedinis induced important modifications to the contents of the cell wall‐bound phenolic compounds and lignin, which made it possible to distinguish between resistant and susceptible cultivars. The post‐infection contents of cell wall‐bound phenolic compounds underwent a rapid and intense increase with a maximum accumulation on the tenth day for p‐hydroxybenzoic acid (1.54 μmol/g), p‐coumaric acid (2.77 μmol/g) and ferulic acid (2.64 μmol/g) and on the fifteenth day for sinapic acid (1.85 μmol/g). The maximum contents accumulated in the resistant cultivar were greater than those in the susceptible cultivar, namely, 11 times for p‐hydroxybenzoic acid, 2.6 times for p‐coumaric acid, 1.8 times for ferulic acid and 12.3 times for sinapic acid. In the susceptible cultivar, p‐coumaric acid and ferulic acid contents also increased after inoculation although they did not reach the pre‐infection contents of the resistant cultivar. The contents of p‐hydroxybenzoic acid in the susceptible cultivar roots did not present post‐infection modification and those of sinapic acid decreased instead. The lignin contents increased in both cultivars with a maximum accumulation on the fifteenth day. However, the maximum contents accumulated in the resistant cultivar roots were 1.5 times greater than those of the susceptible cultivar. These results showed clear differences between the resistant BSTN and the susceptible JHL cultivars. The implication of cell wall‐bound phenolic compounds and lignin in the resistance of date palm to F. oxysporum f. sp. albedinis appears to be dependent on the speed and intensity of their accumulation with greater contents in the first stage of infection.