Disease-yield relationship in barley. II. Contribution of stored stem reserves to grain filling

The effect of disease in two cultivars of barley, sown at different times in two seasons, on the relative importance of stored carbohydrate reserves and current photosynthesis for grain filling was assessed. Three methods of measuring stem reserve contributions to grain filling are reviewed and compared. Disease reduced stem dry weight and the amount of stored carbohydrate in most situations. In contrast, the total amount of stored carbohydrates used for grain filling was often increased by disease. The magnitude of these effects varied with the method used for estimation, and was also different in the crops sown at different times and in different seasons. The estimates of stem reserve contributions to grain filling ranged up to a maximum of 50% in some cases. At least 10 t/ha of reserve material was retranslocated in the healthy 1984 crop studied using ¹⁴C pulse feeding, and up to 0.3 t/ha more was utilized in a diseased crop. The effect of disease on the storage and utilization of stem reserves depended on the time of epidemic development, its duration, and the yield potential of the crop. This suggests that crops could be characterized as those which are very sensitive to disease during grain filling, with low stem reserves or high yield potential, and those with lower sensitivity, with more stem reserves or lower yield potential. Such interacting factors could be incorporated in future plant and yield-loss mechanistic models.     

Chromosomal location and genetic relationship of leaf rust resistance genes rph9 and rph12 in barley

ABSTRACT Barley lines Hor 2596 and Triumph are the sources of leaf rust resistance genes Rph9 and Rph12, respectively. An allelism test was performed with F(2) progeny of the cross Triumph/Hor 2596 inoculated with Puccinia hordei. No recombinants were found in a population of 3,858 progeny, indicating Rph9 and Rph12 are alleles. Molecular and morphological markers were used to identify the chromosomal location of these genes in the crosses Bowman/Hor 2596 and Triumph/I91-533-va. A linkage was detected between Rph9 and the flanking sequence-tagged site (STS) markers ABC155 and ABG3 on chromosome 7(5H) at a distance of 20.6 and 20.1 centimorgans (cM), respectively, and to the microsatellite marker dehydrin-9 (HVDHN9) at a distance of 10.2 cM in the Bowman/ Hor 2596 cross. Analysis of isozymes in bulks of the same population showed that Rph9 may be closely linked to the Est9 locus on chromosome 7(5H). The Rph12 locus was linked to the morphological trait locus va (controlling variegated leaf color) on chromosome 7(5H) at a distance of 22.6 cM in the Triumph/I91-533-va cross. Rph12 also was linked with STS marker ABC155 (24.4 cM) and RAPD marker OPA19 (1.5) (17.8 cM). These data indicate that Hor 2596 and Triumph carry a leaf rust resistance gene at the same locus on the long arm of chromosome 7(5H) of barley.     

Occurrence of barley yellow mosaic and barley mild mosaic bymoviruses in Greece

In March 1991, large chlorotic patches appeared in an autumn-sown barley crop growing near Thessaloniki, Greece. Leaves had characteristic mosaic symptoms and immunosorbent electron microscopy and enzyme-linked immunosorbent assay confirmed the presence of both soil-borne mosaic viruses of barley, barley mild mosaic and barley yellow mosaic bymoviruses. In the following year, similar symptoms appeared in a crop at Souroti, 30 km east of Thessaloniki but the disease has not been found in other areas of Macedonia. This report is the first record of these viruses from Greece and is the most southerly European record.     

Some studies of competition between Avena fatua L. and spring barley I. The influence of A. fatua on yield of barley

A. fauta reduced yields of spring barley in the majority of 51 experiments carried out during 1971 and 1972. Infestations ranging from 8 to 662 seedlings/m² in the spring resulted in yield reductions varying from nothing to 72%; in 11 experiments these exceeded 1–2 t/ha. Reductions in yield were poorly correlated with numbers of seedlings, panicles or wild oat seeds produced. However, there was a good correlation between yield loss and the dry weight of wild oats at harvest. Growth and competitive effects of wild oats differed between the two years. Grain losses were due mainly to reductions in the numbers of ear bearing barley tillers. The influence and significance of the effect of competition on the size of barley grains is discussed.     

Coat protein-mediated resistance to isolates of barley yellow dwarf in oats and barley

Tissue cultures of GAF30/Park oats were biolistically co-transformed with constructs containing the coat protein (CP) genes of the P-PAV, MAV-PS1 or NY-RPV isolates of barley yellow dwarf virus (BYDV), together with a construct containing the bar gene for herbicide resistance and the uidA reporter gene. Transformed, herbicide-resistant tissue cultures were screened by PCR for the presence of the CP genes. Fertile regenerated plants were recovered from some CP-transformed tissue cultures. T₁ progeny of these plants were screened for resistance to the BYDV isolate corresponding to the introduced gene by inoculation with viruliferous aphids followed by ELISA tests. Variation in ELISA values for GAF30/Park control plants made interpretation of the data difficult, but oat plants resistant to each of the three isolates of BYDV (ELISA values less than 0.3; virus titers equivalent to less than 25% of infected controls) were identified in T₁ generations. Further testing of MAV-PS1 CP-transformed lines to the T₂ generation, NY-RPV CP-transformed lines to the T₃ generation and P-PAV CP-transformed lines to the T₄ generation identified further resistant plants. Similarly, immature embryos and calli of the barley cultivar Golden Promise were biolistically bombarded with constructs containing the CP gene of the P-PAV isolate of BYDV and the bar and uidA reporter genes, lines of self-fertile P-PAV CP-transformed barley plants were developed, and T₁plants were screened for resistance to P-PAV. Eight plants from six lines showed moderate to high levels of resistance to P-PAV that correlated with the presence of the CP gene. Plants giving low ELISA values were also found in other lines, even though the CP gene was not detected in these plants. Some T₂ plants derived from resistant parents that contained the CP gene were themselves highly resistant.     

Host responses to fungal penetration in Evysiphe graminis f.sp. hordei infections in barley

Resistance mechanisms restricting penetration and establishment were investigated in an incompatible interaction using an avirulent race CC/3 (BMV 1 + 4) of Erysiphe graminis f.sp hordei on barley cv. Athos (BMR 2 + 5) and a compatible interaction using the universal susceptible cv. Golden Promise (BMR 0). In both interactions: (i) auto-fluorescence of the host cell wall occurred adjacent to the primary germ tube tip after 4 h, and by 10 h near to the appressorial germ tube; (ii) strongly fluorescing papillae developed after 12 h, being frequently associated with failed penetrations; and (iii) only 30% of the attempted penetrations from appressorial lobes resulted in an incipient haustorium at 16 h. Hypersensitive reactions occurred in cells with an incipient haustorium in 30% of appressorial penetrations on Athos, but only in 4% of those on Golden Promise. Twenty per cent of hypersensitively reacting cells in Athos appeared dead by 14 h using trypan blue (membrane exclusion test), compared with 5% for neutral red, suggesting that plasma membrane damage is an early event in the hypersensitive response. Haustorial death was associated with host cell death, but did not precede it; appressorial death occurred 2-4 h after that of the host cell.     

Inheritance of resistance to paraquat in barley grass Hordeum glaucum Steud.

Two biotypes of the grass weed barley grass (Hordeum glaucum), one resistant and the other susceptible to the herbicide paraquat, were studied along with their F₁, F₂ and F₃ progeny to determine the inheritance of paraquat resistance. The plants were sprayed with 50–200 g a.i. paraquat ha^?1. These concentrations killed the susceptible type. The data obtained from segregating populations indicated that paraquat resistance in H. glaucum is controlled by a single nuclear gene with incomplete dominance.     

The spread oi Erysiphe graminis f. sp. hordei in mixtures of barley varieties

A model is proposed of mechanisms which might affect the progress of Erysiphe graminis f. sp. hordei in mixtures of barley varieties. Results obtained from two field trials indicate that the efffect of mixtures may be panitioned into three categoriesof the influence of the reduced density of the susceptible plants, the barrier effect of the resistant plants, and the induced resistance due to the non-virulent pathogen biotypes. In the early stages of plant growth the lower density of susceptible plants accounted for most of the reduction in pathogen development in mixtures. As the epidemic progressed, the barrier and induced resistance effects increased in importance and the total mixture effect was at a maximum mid-way through epidemic development. Towards the end of the trials the overall mixture effect declined though the influence of induced resistance was at its maximum. The reasons for these changes and their implications for the use of host varietal mixtures in disease control are discussed.
Mixtures also protected the crop against a pathogen other than the target organism.     

Enhancement of asulam resistance in barley

Surface sterile excised embryos in barley var. Midas were used to establish whether the embryos could provide a screening procedure for increasing the levels of resistance to asulam in this variety. The embryos incubated in 1–5 mg 1^?1 asulam were susceptible to the lowest concentration, but showed a linear response of increasing percentage mortality with increase in log dose of asulam in the same way as intact glasshouse grown seedlings sprayed with a range of 1–5 × 10³ mg 1^?1 asulam. There was a 100% mortality of the embryo-derived seedlings in the 2–5 mg 1^?1 asulam 25 days after the start of the incubation. During this time growth was recorded as percentage greening, leaf number and shoot length which all showed a marked decline with concentrations of asulam up to 5.0 mg 1^?1. The inhibitory effect of asulam on growth was decreased by the addition of folic acid or 4-aminobenzoic acid to the medium, suggesting that the mode of action of asulam as an inhibitor of folic acid synthesis was the same in the excised embryos as in intact plants. In order to screen for asulam resistance using the excised culture method, 1500 excised embryos were incubated on 5.0 mg 1^?1 asulam. The resistance was measured by selecting those individuals which showed 75% or more growth compared with the untreated control. The selected individuals set self-pollinated seed (S₁), then excised embryos from the S₁ seed were screened again for resistance to asulam and set seed again to produce further progeny (S₂). A comparison of excised embryos from S₁ and S₂ seed with the parental stock showed enhanced resistance in both S1 and S2 where percentage greening and leaf number were used as the growth parameter, but no difference was recorded for shoot length between parent and selected progeny. Améelioration de la résistance de l'orge à l'asulame Des excisats embryonnaires stériles d'orge, variété Midas, ont servi àétudier si les embryons pouvaient fournir une méthode de sélection pour améliorer les niveaux de résistance à l'asulame chez cette variété. Les embryons placés en incubation dans des solutions de l à 5 mg 1^?1 d'asulame étaient sensibles dès la concentration la plus basse, mais il y avait une réponse linéaire de l'augmentation de pourcentage de mortalité avec l'augmentation du logarithme de la dose d'asulame, de la même façon que sous serre avec des semis traités avec des doses de l à 5 g 1^?1 d'asulame. Il y a eu une mortalité de 100% des semis issus des embryons 25 jours après le début de l'incubation avec 2 à 5 mg 1^?1 d'asulame. Pendant ce temps, le développement était noté: % de surface verte, nombre de feuilles, longueur de tige diminuaient tous avec les concentrations d'asulame jusqu'à 5 mg 1^?1. L'effet inhibiteur de l'asulam sur la croissance était réduit de moitié par l'adjonction d'acide folique ou d'acide 4 amino benzoïque, ce qui donne à penser que le mode d'action de l'asulame en tant qu'inhibiteur de la synthèse de l'acide folique est le même chez l'embryon excisé et chez la plante entière. En vue de faire une sélection pour la résistance à l'asulame à l'aide de la méthode de culture excisée, 1500 embryons excisés ont été incubés sur une solution à 5 mg 1^?1 d'asulame. La résistance était estimée en sélectionnant les plantes qui avaient une croissance d'au moins 70% par rapport au témoin non traité. Les individus sélectionnés donnaient des semences par autofécondation (S₁); puis les embryons excisés à partir de S₁étaient de nouveau triés pour la résistance à l'asulame et donnaient de nouvelles semences pour produire la future lignée (S₂). La comparaison des embryons excisés à partir des semences S₁ et S₂ avec le stock parental montraient une amélioration tant pour S₁ et S₂ au niveau du pourcentage de surface verte et du nombre de feuilles; en revanche, aucune différence n'a été enregistrée entre les parents et la lignée sélectionnée sur la longueur des tiges. Erhöhung der Resistenz gegen Asulam bei Gerste Mittels isolierten, oberflächen-sterilisierten Embryonen von Gerste (Sorte Midas) wurde versucht, eine Screeningmethode aufzubauen, mit dem Ziel, bei dieser Art die Erhöhung der Resistenz gegen Asulam zu prüfen. Isolierte Embryonen, die 1–5 mg 1^?1 Asulam exponiert worden waren, erwiesen sich schon gegen die niedrigste Dosierung als empfindlich, zeigten aber eine lineare Beziehung zwischen zunehmender Mortalität in % und steigender log. Dosierung von Asulam. In gleicher Wise reagierten intakte, im Gewächshaus gezogene Keimpflanzen, die mit 1–5 × 10³mg 1^?1 Asulam besprüht worden waren. Die aus den in 2–5 mg 1^?1 Asulam kultivierten Embryonen herangewachsenen Jungpflanzen starben 25 Tage nach Behandlungsbeginn zu loo % ab. Während dieser Periode wurde das Wachstum in %, beurteilt nach‘Grün-Zustand,’Blattzahl und Sprosslänge registriert; alle Kriterien zeigten eine markante Abnahme bei Asulamkonzentrationen bis 5,0 mg l^?1. Der wachstumshemmende Effekt von Asulam wurde durch Zugabe von Folsäure oder 4-Aminoben-zoesäure zum Kulturmedium verringert. Dies lässt vermuten, dass sowohl in den isolierten Embryonen als auch in intakten Pflanzen Asulam in gleicher Weise als Inhibitor der Folsäuresyn-these wirkt. Zur Prüfung der Resistenz gegen Asulam wurden 1500 isolierte Embryonen auf einem 5,0 mg 1^?1 Asulam enthaltenden Medium kultiviert. Als erhöht resistent wurden diejenigen Individuen betrachtet, welche 75 und mehr % Wachstum (verglichen mit Kontrollen ohne Asulam (aufwiesen. Diese Exemplare wurden selektioniert und bis zur Blühreife weiterkulliviert. Durch Selbstbestäubung entstand eine erste Samengeneration (S₁), aus der wiederum Embryonen isoliert und auf ihren Resistenzgrad getestet wurden. Nach dem gleichen Auswahlverfahren erfolgte die Gewinnung einer zweiten Samengeneration (S₂). Ein Vergleich der aus S₁ und S₂ isolierten Embryonen mit der Elterngeneration ergab, dass sowohl S₁ als auch S₂ eine erhöhte Resistenz aufwiesen, wenn ‘Grün-Zustand’ und Blattzahl als Parameter für das Wachstum eingesetzt wurden; es zeigte sich jedoch keine Differenzzwischen Eltern und Nachkommenschaft bezüglich Sprosslänge.     

Immigration of the barley mildew pathogen into field plots of barley

Immigration of the barley powdery mildew pathogen ( Erysiphe graminis f.sp. hordei ) into field plots of the spring barley variety Tyra (carrying the resistance allele Mla1 ) was investigated. Spores were trapped from the top of the plot canopies, as well as from control plots of wheat with no barley nearby. Comparison of the frequencies of virulent and avirulent single-colony isolates showed that the amount of immigration, relative to the amount of inoculum being produced within the plot, reduced very rapidly, until it could not be detected in the middle of the growing season (mid-June).     

Response of foreign barley cultivars to barley yellow mosaic virus at different sites in China

About 90 barley cultivars mostly of European or Japanese origin, were grown for 2–5 years at eight sites in China where barley yellow mosaic virus was known to occur. The sites were selected because they had previously been used to screen breeding lines and some differences between them in cultivar response had been suspected. ELISA tests showed that symptomless plants were not infected by the virus and the proportions of plants with symptoms were therefore recorded as a measure of susceptibility. European cultivars carrying the ym4 gene, which confers resistance to the common European strain, were usually resistant at two sites but susceptible at the others, but one (cv. Energy) was resistant at all sites. Eleven of the Japanese cultivars showed differential responses between sites but there was no correspondence with strains recognized in Japan. There are probably several distinct Chinese strains but further experiments would be needed to identify them. The Japanese cultivars Chosen, Hagane Mugi, Iwate Mensury 2 and Mokusekko 3 seem to be resistant to all known virus strains and are probably the most useful for plant breeders.     

Growth characteristics of spring barley and selected weeds. I. Effect of irradiance in growth chambers

A study in growth chambers with three irradiance levels was carried out over a four-week period on individual seedlings of spring barley (Hordeum vulgare L.) and five weed species (Brassica rapa L. ssp. oleifera (DC.) Metzger, Chenopodium album L., Galeopsis tetrahit L., Stellaria media (L.) Vill., and Viola arvensis Murray). Increased irradiance resulted in larger dry weight, net photosynthetic rate, relative growth rate (RGR), net assimilation rate (NAR), and lower leaf area ratio (LAR). The number of leaves per plant, plant length, leaf area, and shoot/root ratio were unaffected by irradiance levels, During the experimental period the net photosynthetic rate increased, while NAR remained the same, and RGR, LAR, and shoot/ root ratio decreased. On the basis of leaf area and dry weight, especially at the high irradiance level during the last part of the experimental period, barley, B. rapa, and C. tetrahit had the largest values, followed by C. album and S. media with medium values, and V. arvensis with the smallest values. As for leaf area and dry weight, S. media took more advantage of the low than the high irradiance level compared with C. album. Species differences are discussed with regard to competitive ability.     

The metabolism of carboxin in growing barley

The major soluble metabolite of carboxin (2,3-dihydro-6-methyl-5-phenylcarbamoyi-1,4-oxathiin) in barley seedlings and mature plants was identified as the-hydroxy phenyl derivative. This phenol was also bound to the lignin fraction. The distribution of carboxin and its metabolites in seedlings and mature plants grown from treated seed was studied; maximum residues were found in the three oldest internodes, with traces in the roots and flowering heads. Treated plants had altered chlorophyll/carotenoid ratios, and raised levels of some free amino acids.     

Resistance to powdery mildew in one Spanish barley landrace hardly resembles other previously identified wild barley resistances

Two major quantitative trait loci (QTLs) associated with resistance to powdery mildew (Blumeria graminis f. sp. hordei) were previously identified on chromosome 7H of the Spanish barley line SBCC097. The two QTLs seemed to share the same chromosomal position as the major genes mlt and Mlf, which were formerly described in Hordeum vulgare ssp. spontaneum-derived lines. In the present work, different lines that carry mlt (RS42-6*O), Mlf (RS137-28*E), or a combination of both (SI-4 and SI-6) were compared with SBCC097 to evaluate their relatedness at the phenotypic, cellular, and genetic levels. The resistance of the lines was characterised by inoculating them with a set of 27 isolates of B. graminis, which displayed a wide range of virulence. It was revealed that SBCC097 possessed a distinctive resistance spectrum. Microscopic assessment of the cytological development of the resistance response showed that SBCC097 clearly formed fewer well-established colonies and secondary hyphae than the other lines. This was confirmed by the infection type recorded after visual inspection. Genetic analyses of all five lines, based on markers flanking the QTLs derived from SBCC097, supported the macroscopic and microscopic data and pointed to the presence of a combination of novel genes or alleles in SBCC097, which may be included in the category of “intermediate-acting” genes, governing resistance mainly at the post-penetration stage.     

Identification of barley yellow mosaic virus by immuno-electron microscopy in barley but not in Polymyxa graminis or Lagena radicicola

Samenvatting Gerstegeelmozaïekvirus (BaYMV) werd in een perceel wintergerst (cv. Igri) gevonden by Wittem in Limburg, Nederland. Het virus werd met immuno-elektronen-microscopie geïdentificeerd in bladweefsel als BaYMV. In de wortels van geïnfecteerde planten werden alle vormen die van de schimmel-vector (Polymyxa graminis Led.) bekend zijn aangetroffen nl. cystosori, plasmodia en zoosporangia. Inwendig kon geen BaYMV worden aangetoond of waargenomen inPolymyxa ofLagena spp.Cooperative investigation of the ARS, USDA, the Nebraska Agricultural Experiment Station, and the Plant Protection Service, Wageningen. Research conducted under Project 21-12. Published as Paper No. 7787, Journal Series, Nebraska Agricultural experiment Station. Mention of a trademark or proprietary product does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

白粉病菌侵染诱导的大麦叶肉细胞变化的超微结构与细胞化学

 从超微结构和细胞化学角度对大麦白粉病菌侵染诱导的寄主叶肉细胞变化进行了研究。结果发现,病原菌接种后12 h,叶肉细胞光合作用的标志性酶RCA和Rubisco含量发生迅速的变化,感病大麦(Ingrid)中RCA和Rubisco含量急剧减少,而抗病大麦(mlo-3)中则趋势相反。随后,不论在感病或抗病大麦中这2种蛋白的含量一直下降,但感病品种中一直维持相对较高水平。超微结构观察表明,病原菌侵染能够诱导侵染点附近叶肉细胞中叶绿体的增殖,新叶绿体的不断产生,从而延缓了叶肉细胞的衰老和死亡,增加了光合产物的形成。以上结果说明,叶肉细胞可能从养分供给上影响到了表皮细胞中病原菌吸器的发育。     

Structure-activity relationships in fungitoxicants related to triforine and chloraniformethan. II. Redistribution on barley and marrow seedlings

Structural factors governing the redistribution of triforine, chloraniformethan and related compounds on barley and marrow leaves have been investigated. Replacing the 3,4-dichloroanilino or piperazino groups gave compounds which in general underwent acropetal movement, and the degree of redistribution was greatest with the more hydrophilic compounds. Replacing the trichloromethyl by other halogenomethyl groups, or replacing the formyl by other keto groups, gave compounds which were not redistributed. No significant redistribution of any compound in the vapour phase was observed.     

The distribution of barley yellow mosaic virus (BaYMV) and barley mild mosaic virus (BaMMV) in UK winter barley samples, 1987-1990

Improved diagnosis of barley yellow mosaic (BaYMV) and barley mild mosaic (BaMMV) viruses was obtained by adjusting the buffers used in immunospecific electron microscopy (ISEM) to ensure a pH ≥ 7-0 and in ELISA by replacing ovalbumin with 10 g/l full cream milk powder.
Over 70% of samples of winter barley with symptoms of mosaic received from different sites in the UK during 1987-90 had BaYMV and 37% had BaMMV, with 11% containing both viruses. BaMMV was much more common on malting cultivars than on those grown for feed and this resulted in an easterly bias to the geographical distribution of the virus. Both viruses were, however, widely distributed in areas where winter barley is grown intensively. A small number of BaYMV records were from cultivars previously regarded as resistant and these are probably a distinct strain of the virus.