Carbohydrate and enzymic characterization of a high sucrose sugary inbred line of sweet corn

Reserve carbohydrates were determined on developing endosperm of a new line of sugary maize (Zea mays L.). Other entries, included for comparative purposes, were Midway (sugary), Funks G4646 (starchy), and Illini X-tra Sweet (shrunken-2). Sucrose in the new line, Illinois 677a, was more than twice that of Midway at most stages of development, and reached a maximum of 40% of dry weight at 18 days after pollination. Appreciable phytoglycogen accumulated in Illinois 677a, reaching 30% or more of dry weight as endosperm tissue matured. Thus, Illinois 677a is a typical sugary maize concerning phytoglycogen content, but it resembles shrunken-2 concerning the extent of sucrose accumulation.     

互花米草与芦苇光合色素含量对淹水措施的响应

以上海崇明东滩入侵植物互花米草与本地种芦苇为研究对象,研究持续淹水胁迫对两种植物光合色素含量的影响.结果表明：互花米草与芦苇叶片的光合色素基本组成与含量不同,对持续淹水的响应也不同.在持续淹水胁迫下,互花米草叶绿素a、叶绿素b及类胡萝卜素含量降低,叶绿素a／b、类胡萝卜素／叶绿素值提高;芦苇各色素含量升高,叶绿素a／b、类胡萝卜素/叶绿素值基本保持稳定.解除持续淹水胁迫后,互花米草各色素含量逐渐升高,叶绿素a／b、类胡萝卜素／叶绿素值降低,并逐渐接近对照水平;而芦苇各色素含量显著高于对照.两种植物均表现出一定的补偿效应,但芦苇比互花米草更能适应同等程度的持续淹水胁迫.应用持续淹水措施治理互花米草时,可采用本地种芦苇作为治理后湿地恢复的替代植物.     

The response of sorghum and sunflower to short-term waterlogging

Summary Sorghum and sunflower were waterlogged for nine days during the vegetative, floral initiation/buds-visible or anthesis stage of growth under glasshouse conditions to observe the effects on root growth and development. In addition, some plants were waterlogged at all three stages to observe any adaptations induced by waterlogging. The most marked effects occurred at the initiation/buds-visible stage where a 30% reduction in root length and a 40% reduction in root dry weight of sorghum occurred with comparable figures for sunflower being 50 and 60% respectively. Generally, sorghum roots had a higher porosity than sunflower which may contribute to its greater tolerance to waterlogging. The observed changes in root growth are discussed in relation to previously documented effects of waterlogging on growth of the two species and changes which occur in the soil environment.     

The response of sorghum and sunflower to short-term waterlogging

Summary The effect of waterlogging on water use and nutrient uptake in sunflower and sorghum was investigated in relation to stage of development of the crops and the timing and duration of waterlogging. Waterlogging at the vegetative and floral initiation stages of plant growth induced a reduction in water use of sunflower, with corresponding declines in leaf expansion and leaf water potential; in sorghum, the transpiration rates were much lower than for sunflower and relatively unaffected by waterlogging. Waterlogging at anthesis, however, caused an immediate reduction in water use in sunflower with a similar but delayed effect in sorghum. The differences in response of these two species are discussed in relation to the relative importance of water stress and nutrient uptake. Plant analysis at maturity indicated that waterlogging at any growth stage reduced both total and seed phosphorus in sunflower; similar effects were recorded with sorghum, with the exception of anthesis waterlogging which did not reduce nutrient uptake. Waterlogging effects on plant potassium levels were variable.     

The response of sorghum and sunflower to short-term waterlogging

Summary The effect of waterlogging on sunflower and sorghum was investigated in relation to stage of development (sunflower-6-leaf, buds-visible, anthesis; sorghum-5-leaf, initiation, anthesis) and duration of waterlogging (3, 6 and 9 days) under glasshouse conditions. Additionally, the potential adaptation of the two crops was observed by waterlogging some plants at all three growth stages. With sunflower, leaf expansion and stem extension were inhibited by waterlogging at the 6-leaf and buds-visible stage although these effects did not always persist until maturity while, with anthesis waterlogging, rapid desiccation of leaves was observed. Yield was most affected by the anthesis waterlogging but no consistent effect on seed number or 1000 seed weight was recorded.Waterlogging sorghum plants suppressed normal tillering but had little effect on dry weight of the main stem. Late tillering was stimulated by waterlogging. Reductions in leaf area occurred at all stages of development in response to waterlogging with these effects being more marked at initiation. Similarly, yield was most reduced by the initiation waterlogging largely as a result of reduced seed number.In neither species was there a clear relationship between duration of waterlogging and subsequent reduction in growth and yield. With respect to yield, stage of development seemed to be of greater importance than the duration of waterlogging. The growth and yield of multiple-waterlogged sunflowers was less affected by the anthesis treatment than that in plants experiencing a single waterlogging, suggesting that some form of adaptation was induced. In contrast, no such response was seen in sorghum.     

Genetic dissection of starch paste viscosity characteristics in waxy maize revealed by high-density SNPs in a recombinant inbred line population

Starch paste viscosity properties are widely used as important indicators for quality estimation in waxy maize. To elucidate the genetic basis of paste viscosity characteristics of waxy maize, seven parameters from the rapid visco analyzer (RVA) profile were analyzed for quantitative trait loci (QTLs) in this study, using a recombinant inbred line population derived from a cross between the inbred lines Tongxi5 and Hengbai522. A high-density linkage map was constructed using 2703 bin markers, covering 1876.20 cM of the whole genome with an average genetic distance of 0.73 cM between adjacent bin markers. Seventy-two QTLs were detected for RVA parameters across 3 years, of which 17 could be identified in 2 years, and 6 identified in all 3 years. Eight QTL clusters were observed to be co-associated with two or more RVA parameters. Three major QTLs, qPV4-1, qTV4-1, and qFV5-2, which explained over 10% of the phenotypic variation, were stably mapped to the chromosomes 4 or 5 in all years. Based on functional annotations, two genes were considered as potential candidate genes for the identified major QTLs. The QTLs and candidate genes identified in this study will be useful for further understanding of the genetic architecture of starch paste viscosity characteristics in waxy maize, and may facilitate molecular breeding for grain quality improvement in breeding programs, and simultaneously provide a basis for cloning of the genes underlying these QTLs.     

Constraints of root response to waterlogging in Alisma triviale

To understand the economics of root aerenchyma formation in wetland plants, we investigated in detail the response of Alisma triviale to waterlogging. We hypothesized costs being associated with development of a large root air space. In three out-door pot experiments, seedlings (1 experiment) and mature plants (2 experiments) were grown under waterlogged and drained conditions for up to 2?months. Waterlogging promoted growth, and was associated with increased root porosity and decreased root density (fresh mass per volume). The increased formation of aerenchyma was associated with a higher root dry matter content for a given root density. Despite improved growth and earlier flowering, the waterlogged plants also showed signs of being constrained by the anoxic substrate, such as shallower roots, and a higher leaf dry matter content. The formation of aerenchyma was associated with costs, such as increased root dry matter content and reduced metaxylem vessel diameter. The faster growth of the seedlings under the waterlogged conditions, despite some signs of being stressed, was possibly a result of decreased requirements to allocate biomass below ground. In mature plants the increased aerenchyma allowed deeper root penetration, and ameliorated the effects of anoxia, reducing the differences in plant traits between the treatments.     

Morphological and physiological responses of two chrysanthemum cultivars differing in their tolerance to waterlogging

Responses to waterlogging of a tolerant chrysanthemum cultivar (‘53-4’) were compared with those of a susceptible one (‘13-13’). Just 4 days of waterlogging were enough to induce wilting and leaf chlorosis in ‘13-13’, but there was no visual damage to the leaves of ‘53-4’ after 8 days of treatment. After 20 days, only a small number of adventitious roots had emerged from ‘13-13’ stems, but many vigorous adventitious roots had formed in ‘53-4’. Waterlogging induced increases in the activity of alcohol dehydrogenase (EC 1.1.1.1), pyruvate decarboxylase (EC 4.1.1.1) and lactate dehydrogenase (EC 1.1.1.27) in both cultivars, but the increases in ‘13-13’ were more pronounced than in ‘53-4’. On the other hand, the activity of superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11) and catalase (EC 1.11.1.6) was higher in ‘53-4’ than in ‘13-13’. Leaves of ‘13-13’ had a higher content of malondialdehyde, and the amount of this stress indicator in ‘53-4’ was stable throughout the waterlogging period. Ethylene production was enhanced by waterlogging in both cultivars, but peak ethylene production occurred 2 days earlier in the tolerant cultivar, and was 3-fold higher than in the susceptible one.     

Carbon gain and photosynthetic response of chrysanthemum to photosynthetic photon flux density cycles

Most models of carbon gain as a function of photosynthetic irradiance assume an instantaneous response to increases and decreases in irradiance. High- and low-light-grown plants differ, however, in the time required to adjust to increases and decreases in irradiance. In this study the response to a series of increases and decreases in irradiance was observed in Chrysanthemum × morifolium Ramat. “Fiesta” and compared with calculated values assuming an instantaneous response. There were significant differences between high- and low-light-grown plants in their photosynthetic response to four sequential photosynthetic photon flux density (PPFD) cycles consisting of 5-minute exposures to 200 and 400 micromoles per square meter per second (μmol m⁻²s⁻¹). The CO₂ assimilation rate of high-light-grown plants at the cycle peak increased throughout the PPFD sequence, but the rate of increase was similar to the increase in CO₂ assimilation rate observed under continuous high-light conditions. Low-light leaves showed more variability in their response to light cycles with no significant increase in CO₂ assimilation rate at the cycle peak during sequential cycles. Carbon gain and deviations from actual values (percentage carbon gain over- or underestimation) based on assumptions of instantaneous response were compared under continuous and cyclic light conditions. The percentage carbon gain overestimation depended on the PPFD step size and growth light level of the leaf. When leaves were exposed to a large PPFD increase, the carbon gain was overestimated by 16 to 26%. The photosynthetic response to 100 μmol m⁻² s⁻¹ PPFD increases and decreases was rapid, and the small overestimation of the predicted carbon gain, observed during photosynthetic induction, was almost entirely negated by the carbon gain underestimation observed after a decrease. If the PPFD cycle was 200 or 400 μmol m⁻² s⁻¹, high- and low-light leaves showed a carbon gain overestimation of 25% that was not negated by the underestimation observed after a light decrease. When leaves were exposed to sequential PPFD cycles (200-400 μmol m⁻² s⁻¹), carbon gain did not differ from leaves exposed to a single PPFD cycle of identical irradiance integral that had the same step size (200-400-200 μmol m⁻² s⁻¹) or mean irradiance (200-300-200 μmol m⁻² s⁻¹).     

Genetic and biochemical characterization of corn inbred lines tolerant to the sulfonylurea herbicide primisulfuron

Summary Inbred lines of corn (Zea mays L.) have been characterized, which exhibit differential sensitivity to the sulfonylurea herbicide primisulfuron (2-[3-(4,6-bis(di-fluoromethoxy) pyrimidin-2-yl)-ureidosulfonyl]-benzoic acid methylester). When treated postemergence with 160 g a.i. per hectare, inbred 4CO exhibited complete tolerance while inbred 4N5 was killed. The F₁ hybrid 4C0 x 4N5 was uniformly tolerant indicating dominance of the tolerance trait. The field observations correlated with laboratory tests in which seedling root growth was measured. Based on IC₅₀, inbred 4CO was more than ten times more tolerant than inbred 4N5. In the F₂ and F₃ generations, a 31 segregation of tolerant and sensitive individuals was observed, consistent with tolerance being inherited as a single dominant trait. Backcrosses of heterozygous F₁ plants with the sensitive parent (4N5) yielded progeny that segreated at the expected 11 ratio. Backcrosses with 4C0 yielded tolerant offspring only. Inhibition characteristics of acetohydroxyacid synthase (AHAS; E.C. 4.1.3.18) were determined. The enzymes from both inbreds and their F₁ hybrid were equally sensitive and strongly inhibited by primisulfuron (IC₅₀: 7 nM). The fate of ¹⁴C-labeled primisulfuron in seedling tissues of inbred 4C0 and the hybrid, 4C0 x 4N5, indicated rapid metabolism with a half-life (t _1/2) of approximately 3 h. On the other hand, the herbicide-sensitive inbred 4N5 was considerably slower to metabolize primisulfuron (t _1/2 >24 h). These data indicate that differential metabolism is the mechanism of tolerance to the sulfonylurea herbicide primisulfuron in tolerant corn.Deceased     

Allocation plasticity and modular structure in clonal graminoids in response to waterlogging

Three clonal rhizomatous graminoids (Carex gracilis, C. vesicaria andCalamagrostis canescens) co-dominants of Central European marshlands, were examined for their response to waterlogging. A three-year growth study was carried with treatments where the water level was (a) below, (b) at, and (c) above the soil surface to assess the changes in allocation of plant biomass and modular structure. In waterlogged plants total biomass production was lower. The relatively greater shoot systems of waterlogged plants were characterized by the production of a greater number of tiller modules (of the order of 20%). Roots were the most supressed organs both in sedges andC. canescens. Higher leaf area ratios and specific leaf areas in stressed plants indicate the relative enlargement of photosynthetic structures where stems form a significant component of the shoot (LWR <0.5 as inCalamagrostis) in unstressed conditions; above-ground biomass in stressed plants decreased. But where leaves form a major part of the shoot (LWR>0.5 as in sedges) then above-ground biomass and rhizomes in stressed plants increased and leaf area index became higher. Variation of the mean module biomass in particular species was also associated with the LWR characteristics: modules ofCarex gracilis andC. vesicaria were stable in biomass in all the treatments and reached 0.97±0.04 g and 0.44±0.03 g, respectively; inCalamagrostis the biomass of tillers varied. The number of modules increased in all species under waterlogging regardless of the architectural and reallocation differences between species. The increase in clonal modules is regarded as a general adaptive response to the stress of waterlogging.     

The immune response of inbred mouse strains to DNP-BGG

The immune response of six inbred mouse strains (SJL, A, C57BL/6, CBA, BALB/c, and DBA/1) to DNP₅₆BGG was tested under three separate immunization schedules: 1 Μg DNP-BGG in 1 mg Al(OH)₃ adjuvant, 50 Μg DNP-BGG in 1 mg A1(OH)₃ adjuvant, and 1 Μg DNP-BGG in complete Freund's adjuvant. Individual serum samples were titered using a modified Farr assay. It was found that the first schedule allowed classification of the mice into responder (SJL, A) and nonresponder (C57BL/6, CBA, BALB/ c, DBA/1) strains. The second schedule produced quantitative as well as qualitative differences among the strains and allowed classification of the mice into higher-responder (SJL, A), intermediate-responder (C57BL/6, CBA, BALB/c), and low-responder (DBA/1) categories. When complete Freund's adjuvant was used in the third schedule, the differences among strains became insignificant. The sera from each strain were pooled and assayed for relative antibody affinity and IgM content. Both of these parameters were dependent largely on the dose of antigen and type of adjuvant used, rather than on the particular mouse strain being studied. The mechanism of adjuvant action, and possible cell interactions in the genetic control of the immune response, are discussed.     

不同产地茅苍术对淹水胁迫的生理生化响应及耐淹性的TOPSIS综合评价

以不同产地茅苍术为试验材料,研究了人工模拟淹水胁迫对不同产地茅苍术植株叶片的生理指标、光合和叶绿素荧光特性的影响,以期为茅苍术耐涝品种的筛选提供理论依据。结果表明:随着淹水胁迫时间的延长,不同产地植株叶片的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均呈先上升后下降趋势,其中SOD、POD分别于第2、6天达最高值;英山、信阳组CAT值均于第2天达最高值,而句容组于第4天达最高值,上升周期最长,且最高值最大;丙二醛(MDA)、游离脯氨酸(Pro)含量均呈上升趋势,7 d时显著高于未处理组;随着淹水胁迫时间的延长,不同产地植株叶片的净光合速率(Pn)、气孔导度(Gs)、胞间二氧化碳浓度(Ci)和蒸腾速率(Tr)均持续下降,7 d时显著小于未处理组,但各产地间差异不显著;随着淹水胁迫时间的延长,不同产地植株叶片的最大光化学量子产量(Fv/Fm)、PSⅡ潜在光化学活性(Fv/Fo)均呈下降趋势,句容组显著大于其他组,且淹水胁迫对茅苍术叶片Fv/Fo的影响比Fv/Fm大。有效光化学量子产量(Fv'/Fm')、表观光合电子传递速率(ETR)、光化学猝灭系数(q P)和非光化学猝灭系数(NPQ)呈先上升后下降趋势,其中各组茅苍术Fv'/Fm'、ETR分别于胁迫第1天时达最高值;英山、信阳组q P、NPQ于第1天达最高值,句容组于第3天达最高值。通过TOPSIS法对生理、光合、叶绿素荧光指标进行综合评价,得出淹水胁迫下3个产地茅苍术植株耐涝性能大小顺序为句容英山信阳。     

Nutrient accumulation and distribution of wheat genotypes in response to waterlogging and nutrient supply

The effect of soil waterlogging and nutrient supply on plant nutrient accumulation and distribution was investigated for two genotypes of winter wheat (Triticum aestivum L.) differing in waterlogging resistance, Bayles and Savannah. Plants were grown in waterlogged or drained sand and fertilized with half-strength or full-strength Hoagland's solution.Waterlogging reduced the concentrations of N, P, K, Mg, and Zn in leaves and stems and increased the concentrations of those elements in the root system. The effects were greater for waterlogging-sensitive Bayles than for waterlogging-resistant Savannah. Higher concentrations of Fe and Mn were found in waterlogged plants compared to the control plants for sensitive Bayles. Waterlogging increased the proportion of N and Zn in the root system and decreased that of K in stems for Bayles. The proportion of Fe increased in leaves and stems for Bayles and Savannah under waterlogged conditions, but to a greater extent for Bayles. Doubling the concentrations of all major and minor nutrient elements supplied to the waterlogged rooting medium improved plant nutrient status and enhanced plant dry matter production.     

Morphological response of Trichophyton mentagrophytes to keratin

Summary The protein keratin can induce a reversible change in morphology of some granular strains ofTrichophyton mentagrophytes leading to a gross appearance which is indistinguishable from the pleomorphic mutation. The only other chemical which induced the same morphological change was a low concentration of sodium acetate. Pleomorphic cultures ofT. mentagrophytes were unaffected.