Oxygen Diffusion from the Roots of Rice Grown under Non-waterlogged Conditions

Three rice varieties, cv. Norin 36, cv. Norin 37 and cv. Yubae, were grown in a loam with a 20 cm water-table which gave aerobic conditions to a depth of not less than 15 to 17 cm. Under these conditions Norin 36 grew more vigorously and tillered more frequently than the other two varieties. The rates of oxygen diffusion at 23°C from roots up to 11 cm in length were however appreciably lower for Norin 36 (4.3 × 10^?8g · cm^?2 of root surface · min^?1) than for Norin 37 or Yubae (c. 7.8 × 10^?8g). A considerable increase (up to 200 %) in the oxygen diffusion rate (ODR) from the roots occurred if they were cooled to 3°C, and at this temperature differences in ODR between the varieties were not significant. For a purely physical system, because of the decrease in the diffusion coefficient of oxygen in water, and, the increase in oxygen solubility, a drop of c. 20 % in ODR should accompany the above 20°C drop in temperature. A 16 % drop was recorded for artificial ‘roots’ under these conditions. It was concluded that respiratory activity at the higher temperature must have been responsible for the low readings and intervarietal differences observed at 23°C. By increasing the 3°C values by 25 % a mean value of 14.2 × 10^?8g · cm^?2 of root surface · min^?1 was recorded for the three varieties, being the probable ODR at 23°C in the absence of a respiratory factor. Calculations show that respiratory activity removed enough oxygen to reduce the ODR for Norin 36 by more than 9 × 10^?8g, and for Norin 37 and Yubae by c. 6.7 × 10^?8g · cm^?2 of root surface · min^?1. Anatomical investigations showed that cortical breakdown was always extensive at 4 to 4.5 cm from the apex of the roots. In some cases however breakdown had not occurred in the basal segment of the root. No opinion could be formed as to whether differences in the amount of cortical breakdown between the varieties might have occasioned the respiratory differences observed. An interesting feature of the root anatomy was the failure of breakdown in those regions of the roots through which lateral roots emerged.     

Investigation of Growth Hormones in Xylem Exudate and Root Tissue 1

Infection of the root system in tomato by the root-knot nematodewas found to alter the gibberellins and cytokinina extractedfrom root tissue and xylum exudate. Gibberellins from the roottissue and xylem exudate of healthy plants occurred in the neutral,acidic, and aqueous fractions. With increasing levels of infection,gibberellins were primarily extracted in the slightly acidicfraction. Gibberellin activity in the neutral, acidic, and aqueousfractions was decreased in diseased plants. Cytokinins, whichwere also extracted from root tissue and xylem exudate, werelower in diseased plants than in uninfected plants.     

Characterization of Anionic Peroxidases in Tomato Isolines Infected by Meloidogyne incognita

Changes in peroxidase activity during nematode infection were studied using root extracts of tomato near-isogenic lines differing in resistance to Meloidogyne incognita. Total peroxidase activity increased slightly in crude extracts of four susceptible isolines but doubled in two resistant lines, Monita and Motaci. Nematode infection enhanced levels of both p-phenylenediamine-pyrocatechol oxidase and syringaldazine oxidase 7 days after inoculation, especially in resistant lines. This elevated peroxidase activity in resistant isolines was caused by an increase in anionic peroxidase activity. These enzymes, which likely are involved in lignification, were isolated and purified from tomato isolines by ammonium sulfate precipitation, high performance ion-exchange chromatography, and gel electrophoresis. The purified anionic peroxidase extracts contained an electrophoretic band with Rf 0.51 that was present in extracts of infected but not uninfected roots.     

Mixed Crystals of Threonine and Allothreonine

Study of the soluble proteins of sweet potato (Ipomoea batatas L. cv. Norin 1) roots showed that the major protein had an apparent molecular weight of 25,000, and accounted for 60 ~ 70% of the total soluble protein extracted from fresh tissue. The 25-kDa protein exists in two forms, which can be resolved into two bands by nondenaturing polyacrylamide gel electrophoresis. Immunodiffusion and crossed immunoelectrophoresis showed that these forms are immunologically identical. This protein was identified as the antigenic component A of sweet potato root.¹⁾ It was degraded to proteins of lower molecular weight (9,500 to 20,000) if the tissue was cut or infected by Ceratocystis fimbriata. As almost none of this 25-kDa protein was detected in roots stored for one year at 10 ~ 12°C, it is probably the storage protein of these roots. Another major protein was identified as β-amylase by immunodiffusion and immunoelectrophoresis. The amount of β-amylase did not change appreciably after cutting or infection, but it was present in only trace amounts in the roots stored for one year, Cutting, infection, or storage of root tissue resulted in the production of new isozymes of peroxidase, acid phosphatase, and esterase. Increases in some other proteins in cut and in diseased tissues were detected by gel electrophoresis.     

Occurrence of Peroxidases in Sweet Potato Infected by the Black Rot Fungus

Changes in the peroxidase activity and the patterns in sweet potato tissue infected by Ceratocystis fimbriata were investigated, by the method of starch-gel electrophoresis, DEAE-cellulose column chromatography and immunochemical analysis, compared with that in cut and healthy tissue. Time-course analysis of the increment of the total peroxidase activity also showed noticeable differences between diseased and cut tissues. The peroxidases in diseased and cut tissues were composed of four major and several minor components. Though electrophoretic analysis did not show so striking differences in the patterns of peroxidases between diseased and cut tissues, there were distinct differences in the ratio of activities of major peroxidase components between both tissues. Immunochemical works indicated that peroxidase A which showed the most prominent increase in diseased tissue was found to be formed in cut tissue though the amounts were appreciably small. The activity of peroxidase C in diseased tissue was not so high as seen in cut tissue.     

粗缩病对玉米产量和籽粒品质的影晌

以6个对玉米粗缩病（MRDV）表现不同抗性的玉米品种为材料,研究了粗缩病对玉米产量性状和籽粒品质的影响。结果表明,在供试品种中,‘青农105’和‘青农8’为抗病品种,‘登海3622’和‘农大108’为中抗品种,‘先玉335’和‘郑单958’为感病品种。感病后,玉米果穗穗长、行粒数、穗粒重和产量显著降低,且损失程度表现为抗病品种〈中抗品种〈感病品种：籽粒中粗淀粉含量显著降低,粗蛋白含量升高,粗脂肪含量变化不明显。回归分析表明,通过旃情指数可以准确预测玉米粗缩病导致的产量损失。     

The mechanism of chilling injury in sweet potato IX. The relation of chilling to changes in mitochondrial respiratory activities

To examine the mitochondrial activity of chilling-stored sweetpotatoes a method of isolating mitochondria with a good respiratorycontrol (RC) ratio from healthy sweet potato tissue was established.Mitochondria were isolated from two varieties of sweet potatoes(Norin No. 1, moderately sensitive to chilling, and OkinawaNo. 100, very sensitive) kept at about 0°C for about 15to 40 days. Respiratory activity was measured with an oxygenelectrode apparatus. Mitochondrial activities of chilling-storedNorin No. 1, i.e. the RC ratio, respiratory rate at state 3and ADP/O ratio decreased about 2 to 3 weeks after the beginningof incubation. The decline in the RC ratio was most sensitive.Diminution of the activities when malate was used was seen earlierthan when succinate was used. When activities were measuredusing succinate at low concentration (0.2 M) of mannitol, thedecrease in activities was more conspicuous than at a high concentration(0.7 M). Similar experiments with Okinawa No. 100 also showedthe decline in these activities. However, the three kinds ofactivities simultaneously decreased, and the decline appearedfaster than in the case of Norin No. 1. ¹ This paper constitutes part 99 of the phytopathological chemistryof sweet potato with black rot and injury. ² Current address: Nomura Research Institute, Kamakura, Kanagawa247, Japan. (Received June 6, 1972; )     

Soluble Proteins, Esterases and Superoxide Dismutase in Stem Tissue of Pepper Plants in Relation to Age-related Resistance to Phytophthora capsici

Patterns of soluble proteins and isoenzymes of esterase and superoxide dismutase were investigated in healthy and infected stems of two pepper cultivars resistant and susceptible to Phytophthora capsici. By the use of two-dimensional SDS-polyacrylamide gel electrophoresis, it was possible to compare precisely the cultivars Hanbyul and Kingkun susceptible or resistant to P. capsici with respect to their protein patterns. The two-dimensional electrophoresis identified three proteins (25—27 kD) from the healthy stem extracts of Kingkun, which were absent in Hanbyul. Some particular proteins appeared in pepper stems of both cultivars at later developmental stage of plants, suggesting their role in the expression of age-related resistance. Some proteins which were not detectable in the healthy stem extracts also existed in large amounts in the diseased ones. By contrast, other proteins present in the healthy stems disappeared from the diseased stems. Some esterase isoenzymes appeared in the two cultivars only at late developmental stage. Other esterase isoenzymes were produced only in the diseased stems. There were no differences in the patterns of superoxide dismutases between the cultivars and also between developmental stages. Large activities of several superoxide dismutases were detected in the diseased stems.     

Nitrogen metabolism and water regime of rice plant affected by “brusone” disease

Summary The factors which influence disease development greatly affect the nitrogen metabolism and water regime of the rice plant. Soluble nitrogen, mainly the amino acids, accumulates and this favours the establishment of parasitic micro-organisms. In diseased tissues the level of total-N and protein-N (per cent on dry weight) is higher than in the healthy ones. If the amount of protein-N is expressed on a total-N basis the diseased plants exhibit a lower protein content.High nitrogen doses lead to disturbances of the growth processes and may be attributed to the accumulation of NH₃. The physiological activity of the root system of susceptible and resistant rice plants exhibits marked differences, particularly in the later developmental stages. Resistant varieties, due to their highly developed root system, yielded higher amounts of bleeding sap.As a result of excessive nitrogen nutrition the root/shoot ratio is shifted in favour of the latter and consequently the normal balance of water regime and the mineral nutrition is disturbed. In the so called brusone years physiological drought is observed and this leads to serious losses. The resistant varieties are more or less tolerant to the deleterious effect of physiological drought.     

Endophytic microorganisms as potential growth promoters of banana

The potential of endophytic microorganisms in promoting the growth of their host plant was determined by artificially introducing five isolates (bacterial and fungal strains: UPM31F4, UPM31P1, UPM14B1, UPM13B8, UPM39B3) isolated from the roots of wild bananas into both healthy and diseased banana plantlets (Berangan cv. Intan). The response of the host plants to endophytic infection was assessed by measuring the change in four growth parameters: plant height, pseudostem diameter, root mass and total number of leaves. The endophytes tested as growth promoters were found to have a significant effect in both healthy and Fusarium-infected (diseased) plantlets. In both experimental systems, the bacterial isolate UPM39B3 (Serratia) and fungal isolate UPM31P1 (Fusarium oxysporum) showed promising growth-promoting properties. Isolate UPM39B3 (Serratia) induced the largest increases in all four growth parameters in healthy plantlets – 3.14 cm (height), 1.12 cm (pseudostem diameter), 2.12 g (root mass) and 1.12 (total number of leaves plant⁻¹) – followed by isolate UPM31P1 (Fusarium oxysporum). The beneficial effect of UPM39B3 (Serratia) and UPM31P1 (Fusarium oxysporum) was also reflected in the diseased plantlets, where pre-treatments with the isolates either singly (T6: UPM31P1; T8: UPM39B3) or in a mixture (T7: UPM31P1 + UPM39B3; T9: UPM14B1 + UPM13B8 + UPM39B3) were able to sustain the growth of plantlets, with significantly higher growth values than those in diseased plantlets that were not infected with endophytes (T10: FocR4). These results demonstrate the economic significance of these endophytic isolates, particularly UPM39B3 (Serratia) and UPM31P1 (Fusarium oxysporum), both as potential growth promoters of banana and as agents rendering tolerance towards Fusarium wilt as a strategy in the management of Fusarium wilt of banana via improved vegetative growth.     

Relationship between the concentration of sugars in the roots and VA mycorrhizal infection

Summary The VA-infected wheat varieties showed an increase of total (Lozano var.) and reducing (Lozano and Pane vars.) sugars in their root extracts. However, no clear relationship between sugar concentration in the root and VA mycorrhizal infection level could be established.In addition, the VA mycorrhizal hosts sorghum, alfalfa, sunflower and maize, and non-host radish and cabbage plants were tested for sugar content in their root extracts after fifteen days of growth. Sugars present in the root extracts of these plants did not seem to be a decisive factor in plant susceptibility to VA infection.     

UV radiation-sensitive norin 1 rice contains defective cyclobutane pyrimidine dimer photolyase

Norin 1, a progenitor of many economically important Japanese rice strains, is highly sensitive to the damaging effects of UVB radiation (wavelengths 290 to 320 nm). Norin 1 seedlings are deficient in photorepair of cyclobutane pyrimidine dimers. However, the molecular origin of this deficiency was not known and, because rice photolyase genes have not been cloned and sequenced, could not be determined by examining photolyase structural genes or upstream regulatory elements for mutations. We therefore used a photoflash approach, which showed that the deficiency in photorepair in vivo resulted from a functionally altered photolyase. These results were confirmed by studies with extracts, which showed that the Norin 1 photolyase-dimer complex was highly thermolabile relative to the wild-type Sasanishiki photolyase. This deficiency results from a structure/function alteration of photolyase rather than of nonspecific repair, photolytic, or regulatory elements. Thus, the molecular origin of this plant DNA repair deficiency, resulting from a spontaneously occurring mutation to UV radiation sensitivity, is defective photolyase.     

Variation of glucosinolates on position orders of flower buds in turnip rape (Brassica rapa)

To glucosinolate (GSL) contents on flower buds depending on their position orders in turnip rape (Brassica rapa), three Japanese ‘Nabana’ cultivars such as cv. No. 21 (Brassica rapa, early type), cv. Husanohana (B. rapa, late type) and cv. Norin No. 20 (B. napus) were investigated using HPLC analysis. Ten GSLs including glucoraphanin, sinigrin, glucoalyssin, napoleiferin, gluconapin, 4-hydroxyglucobrassicin, glucobrassicanapin, glucobrassicin, and gluconasturtiin were detected. Differences in individual and total GSL contents were found between two plant varieties, which are also depending on various developmental stages. Among the GSLs, gluconapin (mean 23.11 μmole/g dry weight (DW) and glucobrassicanapin (mean 13.41 μmole/g DW) documented the most abundant compounds and contributed average 39 and 27% of the total GSLs, but indolyl and aromatic GSLs together accounted >10% of the total GSLs. The presence of significant quantities of gluconapin in the cultivars should be studied more extensively, since the GSL is mainly responsible for the bitter taste.     

Role of Phytotoxins in Pine Wilt Diseases

Characteristic rapid death of pines after infection by Bursaphelenchus xylophilus suggests the involvement of phytotoxins in the pine wilt disease syndrome. Crude extract from diseased pine is toxic to pine seedlings, whereas an extract from healthy pine is not. The response of seedlings to the crude toxin is more prominent in susceptible pine species than in resistant ones. Benzoic acid, catechol, dihydroconiferyl alcohol, 8-hydroxycarvotanacetone (carvone hydrate), and 10-hydroxyverbenone, which are toxic, low molecular weight metabolites, can be isolated from diseased pines. Other unidentified toxins are also found. The toxicity of some of these metabolites correlates positively to the susceptibility of pines to B. xylophilus. Some of these abnormal metabolites show synergistic toxicity when in combination. The D-isomer of 8-hydroxycarvotanacetone, dihydroconiferylalcohol, and 10-hydroxyverbenone inhibited the reproduction of B. xylophilus. Cellulase excreted by pinewood nematode also may be involved in rapid wilting.     

Accumulation of antifungal compounds in tea leaf tissue infected withBipolaris carbonum

Varietal resistance of tea towardsBipolaris carbonum was tested following detached leaf inoculation technique. Among the fourteen varieties tested, three were found to be highly susceptible, while other three were resistant. Leaf exudates and diffusates collected from the resistant varieties were more fungitoxic than those from the susceptible ones. Two antifungal compounds isolated from healthy andB. carbonum-infected tea leaves exhibited clear inhibition zones atR _F 0.8 and 0.65, respectively, in a chromatographic bioassay. On the basis of their color reaction on TLC and UV-spectra these were identified to be catechin and pyrocatechol. Resistant and susceptible varieties accumulated 439–510 and 187–212 μg/g fresh mass tissue of pyrocatechol, respectively, 2 d after inoculation withB. carbonum, while a low concentration (45–58 μg/g) of this compound was detected in healthy leaf tissue.     

UV Radiation–Sensitive Norin 1 Rice Contains Defective Cyclobutane Pyrimidine Dimer Photolyase

Norin 1, a progenitor of many economically important Japanese rice strains, is highly sensitive to the damaging effects of UVB radiation (wavelengths 290 to 320 nm). Norin 1 seedlings are deficient in photorepair of cyclobutane pyrimidine dimers. However, the molecular origin of this deficiency was not known and, because rice photolyase genes have not been cloned and sequenced, could not be determined by examining photolyase structural genes or upstream regulatory elements for mutations. We therefore used a photoflash approach, which showed that the deficiency in photorepair in vivo resulted from a functionally altered photolyase. These results were confirmed by studies with extracts, which showed that the Norin 1 photolyase–dimer complex was highly thermolabile relative to the wild-type Sasanishiki photolyase. This deficiency results from a structure/function alteration of photolyase rather than of nonspecific repair, photolytic, or regulatory elements. Thus, the molecular origin of this plant DNA repair deficiency, resulting from a spontaneously occurring mutation to UV radiation sensitivity, is defective photolyase.     

Peroxidase and chitinase isoenzyme activities during root infection of Chinese cabbage with Plasmodiophora brassicae

Roots of two Chinese cabbage (Brassica campestris L. ssp. pekinensis) varieties, one tolerant and one susceptible, were inoculated with Plasmodiophora brassicae in liquid medium and in soil. Chitinase and peroxidase activities were determined in roots and shoots 1–21 days after inoculation with resting spores of Plasmodiophora and the enzyme activities compared with healthy tissue of the same age. In infected roots of the susceptible variety ‘Granat’ chitinase activity was higher than in the control 10 days after inoculation with spores. In the tolerant variety ‘Parkin’ we detected an increase in chitinase activity at the same time, which was about twice that of ‘Granat’. Chitinase activity in ‘Granat’ was also enhanced on day 13, 14 and 17 after inoculation, whereas chitinase activity in ‘Parkin’ was lower in the infected roots than in the controls during that period. In the shoots no correlation between chitinase activity and infection in the two varieties was observed. Chitinase from Chinese cabbage was further characterized and showed a pH optimum at pH 4.5–5.5 and a temperature optimum at 35–45°C. After isoelectric focusing 7 isoenzymes were discovered, but there were almost no differences between infected and healthy root extracts. Two isoenzymes with pI 8.7 and 8.8 showed cross-reactivity with an antiserum against bean chitinases. The molecular mass of these isoenzymes was determined as 33 kDa. Total peroxidase activity was generally higher in root tissue of both varieties than in the shoots. Peroxidase activity was increased most prominently in infected ‘Granat’ roots on day 13 after inoculation and of both varieties on day 17 compared to the controls. In clubbed tissue of ‘Granat’ a specific peroxidase isoenzyme appeared the first time 21 days after inoculation and was most prominent 28–30 days after inoculation. This isoenzyme had a molecular mass of ca 24 kDa and a pI of ca 8.8. With respect to our results the strategy of the Plasmodiophorales for plant attack is discussed.     

Antixenotic resistance of subterranean clover cotyledons to redlegged earth mite, Halotydeus destructor

The short-term response of redlegged earth mite, Halotydeus destructor (Tucker) (Acarina: Penthaleidae) to cotyledons of different varieties of subterranean clover (Trifolium subterraneum subsp. subterraneum L.) was assessed by means of paired choice tests, and no-choice tests. H. destructor had lower numbers and fed less on detached cotyledons of resistant than susceptible varieties, yielding a correlation between the numbers of mites and feeding damage to the cotyledons during a three hour test period. For a number of resistant and susceptible varieties, there was a negative correlation between cotyledon deterrence in the three hour choice test and feeding damage to seedling after a two week period. Since the response of the mites to different subclover varieties occurred within three hours, it is concluded that the resistance is based on antixenosis.No evidence was obtained for antifeedant activity in organic solvent extracts from the variety DGI007 (resistant) in comparison with those from the variety Dalkeith (susceptible). Water soluble compounds from DGI007 cotyledons were preferred by mites, in feeding tests in terms of numbers, over those from Dalkeith (susceptible). Squeezed sap from the cotyledons of both varieties showed the same effects on mites as 5% glucose and were more phagostimulatory than water extracts. Mechanically damaged cotyledons of Dalkeith and DGI007 attracted more mites than the undamaged counterparts. The toughness of cotyledons in 17 varieties of T. subterraneum subsp. subterraneum was measured with a manual penetrometer. Results showed a negative correlation between toughness values and mite feeding damage scores (r²=0.752) for all varieties except S3615D (resistant). This implies a likely involvement of epidermal toughness as a contributor in the antixenotic resistance of these varieties. Other mechanisms may be involved in the resistance of S3615D.     

Quantitative studies of the post-penetration phase of infection by Puccinia graminis tritici

Data obtained during the first 120 h after several resistant and susceptible varieties of wheat and some non-host species were inoculated with uredio-spores of Puccinia graminis tritici provided further evidence in support of the suggestion that hypersensitive necrosis is a consequence, and not the cause, of resistance. No evidence was obtained that individual genes for stem-rust resistance specifically influenced colony growth or the histological changes that occurred during infection. However, combinations of major resistance genes or the presence of minor genes for resistance apparently did affect colony growth and hypersensitive cell collapse. Three groups of varieties – resistant, intermediate and susceptible – were distinguished on the basis of colony growth and the amount and proportion of necrotic tissue associated with colony development. The boundary between the intermediate and susceptible groups was not as distinct as that between the intermediate and resistant groups.     

Effect of Sclerospora graminicola infection on total nitrogen content and free aminoacid composition of bajra plants

Summary Studies on the total nitrogen content and free aminoacid composition of healthy Bajra (Pennisetum typhoides Stapf &Hubb.) plants and those infected withSclerospora graminicola (Sacc.)Schroet. were made. Total nitrogen content of the diseased tissues increased as a result of infection. Considerable difference existed in free aminoacid composition of healthy and diseased tissues. Tryptophane was one of the aminoacids which was constantly isolated from the extracts of diseased tissues only.