Conversion of Phosphatidyl Choline to Phosphatidic Acid in Freeze Injured Rye and Wheat Cultivars

The effect of exposure to freezing temperature (?15°C) on leaf phospholipid composition of hardened rye (Secale cereale L.) and hardened wheat cultivars (‘Miranovskaja 808’, ‘Bezostaja 1’, ‘Short Mexican’ and ‘Penjamo 62’), which differ in their resistance to frost, was investigated. Hardening took place under natural conditions. All the seedlings attained an equal level of linolenic acid in their leaves during hardening. Exposure to freezing temperatures resulted in a loss of phosphatidyl choline and accumulation of phosphatidic acid in the leaves. The ratio of phosphatidic acid to phosphatidyl choline, but not the level of poly-unsaturated fatty acids in the leaves, was related to their ability to survive at low temperatures. As freezing injury is caused by the formation of ice crystals in both extra- and intracellular space, it is probable that the plasma membranes of the investigated cultivars differed with respect to their water permeability. It is concluded that the plants, depending on the degree of their resistance to cold, produce an unknown substance of lipidic nature upon exposure to cold, with the aid of which they adjust the transitional state of their membranes to the prevailing temperature and, at the same time, facilitate the efflux of water from the cells.     

Radiation-induced improvement of the freeze-resistance of a cold-sensitive wheat variety: Freeze-tolerance and fatty acid patterns

Effects of 3–15 krad ⁶⁰Co gamma radiation on cereal seeds were investigated with regard to the frost hardiness of leaves of 5–7-day-old seedlings. Comparative studies were carried out on the gas-chromatographically determined distribution patterns of fatty acids in different pools (total fatty acid, total lipid, polar lipids) of a cold-resistant (cv. Mironowskaya 808) and a cold-sensitive (cv. Penjamo 62) cultivar of wheat (Triticum aestivum L.). Parallelism between fatty acid distribution pattern, empirical parameters suggested for quantitative measures of cold tolerance (the ratio unsat/sat and double-bond index), and the low-temperature behaviour of shoots grown from radiation treated seeds of ‘Penjamo 62’, was also examined. To monitor differences in the fatty acid syntheses of ‘Mironowskaya 808’and ‘Penjamo 62’, and to demonstrate radiation-induced changes in fatty acid turnover a [1–¹⁴C]-acetate incorporation technique was employed. The results of practical importance are: 1. A significant improvement in the frost-resistance of the cold-sensitive ‘Penjamo 62’variety could be achieved with 6–9 krad irradiation, the half-freeze-killing temperature dropping from ?6 to about ?18°C. 2. Freeze-hardiness, no matter whether inherited or gained, could be abolished by gamma irradiation with higher dose. The following conclusions of theoretical interest can be drawn: 1. Low-temperature behaviour of plant tissues is a dynamic property rather than a static one, not only the formation but also the breakdown of certain hydrocarbon chains may be of paramount relevance in cold-tolerance. 2. Not the linolenic (18:3) component, but rather the overall distribution pattern of the C₁₈ family seems to correlate with low-temperature-responses of shoots. 3. Empirical parameters investigated do not provide reliable quantitative measures of the susceptibility to freeze (and cold-) injuries. 4. Changes in the syntheses of some key proteins (e.g. peroxidase, water-soluble proteins, etc.) may also be important in adaptation to low-temperature conditions.     

Impact of intercropping aphid-resistant wheat cultivars withoilseed rape on wheat aphid (Sitobion avenae) and its natural enemies

The effects of intercropping of wheat cultivars and oilseed rape on the densities of wheat aphid, Sitobion avenae, and their arthropod natural enemies were evaluated. Three winter wheat cultivars with different resistant levels to S. avenae were used: ‘KOK’ (high resistance), ‘Xiaobaidongmai’ (low resistance) and ‘Hongmanghong’ (susceptible). The results showed that the densities of S. avenae were significantly higher on the monoculture pattern than on either the 8-2 intercropping pattern (eight rows of wheat with two rows of oilseed rape) or the 8-4 intercropping pattern (eight rows of wheat with four rows of oilseed rape). The mean number of predators and the mummy rates of S. avenae were significantly higher in two intercropping patterns than those in the monoculture pattern. The densities of S. avenae, ladybeetles, and mummy rate of S. avenae were significantly different among different wheat cultivars. The highest densities of S. avenae and ladybeetles were found on wheat cultivar Hongmanghong. The lowest densities of S. avenae associated with high mummy rate of S. avenae were found on wheat cultivar Xiaobaidongmai. The results showed that wheat-oilseed rape intercropping conserved more predators and parasitoids than in wheat monoculture fields, and partial resistance of wheat cultivar Xiaobaidongmai had complementary or even synergistic effects on parasitoid of S. avenae.     

Parasitism capacity and searching efficiency of Diaeretiella rapae parasitizing Brevicoryne brassicae on susceptible and resistant canola cultivars

Different cultivars of aplant species can affect the foraging and efficiency of natural enemies, both directly through physical and biochemical properties or indirectly through the herbivore's diet. In this study, the parasitism capacity and functional response of Diaeretiella rapae McIntosh were determined on the cabbage aphid, Brevicoryne brassicae (L.) reared on susceptible (Opera) and resistant (Okapi) canola cultivars under laboratory conditions at 25?±?1?°C, 60?±?5% RH and a16:8?h L:D photoperiod. The parasitoid exhibited Type II and Type III functional responses on the resistant and susceptible cultivars, respectively. The estimated value of searching efficiency (a) was 0.1637?±?0.1095?h^?1 on the resistant cultivar whereas its value was dependent on host density on the susceptible cultivar. The handling times (T_h) on the susceptible and resistant canola cultivars were 0.108?±?0.040 and 0.320?±?0.048?h, respectively. The net parasitism rate (C₀) of the parasitoid wasp varied from 128.09 hosts per parasitoid lifetime on the susceptible to 71.01hosts on the resistant canola cultivar. The transformation rate from host population to parasitoid offspring (Qp) was equal to 1 on both cultivars (C₀?=?R₀). The finite parasitism rate (ω) on the susceptible cultivar (0.819 hosts per parasitoid per day) was significantly higher than that on the resistant one (0.578 hosts per parasitoid per day). In conclusion, canola cultivars affected the performance of D. rapae in controlled small-scale laboratory experiments and compared with the susceptible cultivar, the resistant one had anadverseeffect on the efficiency of the parasitoid.     

Effect of auxin physiological analogues on rapeseed (Brassica napus) cold hardening, seed yield and quality

The effect of the auxin physiological analogues analogues 1-[2-chloroethoxycarbonylmethyl]-4-naphthalenesulfonic acid calcium salt (TA-12) and 1-[2-dimethylaminoethoxicarbonylmethyl]naphthalene chlormethylate (TA-14) TA-14 on different winter rapeseed cultivars were studied with regard to their autumnal growth, cold hardening, accumulation of the stress-protective metabolites proline and saccharide in plant organs: apical bud and root collum, winter survival and productivity formation. The test cultivars were the very early ‘Libea’ medium-resistant to wintering, the medium-early ‘Sunday’ resistant to wintering, the medium–early ‘Valesca’ less than medium resistant to wintering, and the early ‘Hornet’ (hybrid) tolerant to stress growth conditions. During the period of cold hardening in natural field conditions, the test compounds TA-12 (2 mM) and TA-14 (4 mM), applied to different winter rapeseed cultivars at the 4th–5th leaf stage, stimulate accumulation proline and saccharides (sucrose and glucose) in the root collum and apical bud tissues, influence plants acclimation to cold, overwintering and productivity formation. Compounds TA-12 and especially TA-14 produced a stable effect on seed and crude fat yield in cvs. ‘Hornet’, ‘Sunday’ and ‘Libea’. The genotypic peculiarities of a cultivar and the meteorological conditions of the plant vegetation period were the factors that mostly determined fatty acid content in seed oil.     

Isolate Virulence and Cultivar Response in the Winter Wheat: Pyrenophora tritici-repentis (Tan Spot) Pathosystem in Oklahoma

Prevalence of tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma as no-till cultivation in wheat has increased. Hence, developing wheat varieties resistant to tan spot has been emphasized, and selecting pathogen isolates to screen for resistance to this disease is critical. Twelve isolates of P. tritici-repentis were used to inoculate 11 wheat cultivars in a greenhouse study in split-plot experiments. Virulence of isolates and cultivar resistance were measured in percent leaf area infection for all possible isolate x cultivar interactions. Isolates differed significantly (P < 0.01) in virulence on wheat cultivars, and cultivars differed significantly in disease reaction to isolates. Increased virulence of isolates detected increased variability in cultivar response (percent leaf area infection) (r = 0.56, P < 0.05) while increased susceptibility in cultivars detected increased variance in virulence of the isolates (r = 0.76, P < 0.01). A significant isolate × cultivar interaction indicated specificity between isolates and cultivars, however, cluster analysis indicated low to moderate physiological specialization. Similarity in wheat cultivars in response to pathogen isolates also was determined by cluster analysis. The use of diverse isolates of the fungus would facilitate evaluation of resistance in wheat cultivars to tan spot.     

The manipulation of polar head group composition of phospholipids in the wheat Miranovskaja 808 affects frost tolerance

Caryopses of the frost-resistant cultivar of the wheat Triticum aestivum L., Miranovskaja 808, were germinated and grown in the presence of various concentrations of choline chloride. Changes in the composition of leaf total phospholipids and leaf total fatty acids at two extreme temperatures (25°C and 2°C) as well as changes in frost resistance were followed. A choline chloride concentration-dependent accumulation of phosphatidyl choline was observed in the leaves. Seedlings grown at 2°C accumulated more phosphatidyl choline at each choline chloride concentration than those grown at 25°C. There was an inverse relationship between the contents of phosphatidyl choline and phosphatidic acid in the leaves. Neither the temperature nor choline chloride seemed to affect fatty-acid composition. Modification of polar-head group composition of phospholipids affected frost tolerance: Seedlings grown in the presence of 15 mM choline chloride at 25°C exhibited a freezing resistance equal to that of hardened controls. The data indicate that the polar-head group composition of membrane phospholipids in plants can be easily manipulated and point to the importance of phosphatidyl choline in cold adaptation processes.     

Adaptation of membrane fluidity of rye wheat seedlings according to temperature

Order parameters of chloroplast membrane lipids of rye wheat seedlings differing in cold hardiness were compared before after hardening. Seedlings grown at 25° exhibited similar membrane microviscosities. When hardened, the cultivars most resistant to freezing temperatures possessed the most fluid membranes, while those sensitive to cold were unable to alter them. Changes in linolenic acid levels alone cannot be responsible for the observed phenomena.     

Assessing cultivar resistance to Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae) using a phenotyping method under semi‐field conditions

The orange wheat blossom midge, Sitodiplosis mosellana (Géhin), can significantly reduce wheat yield. Growing resistant wheat cultivars is an effective way of managing this pest. The assessment of cultivar resistance in field trials is difficult because of unequal pressure of S. mosellana caused by differences in cultivar heading dates relative to the flight period of S. mosellana adult females and huge variations of egg laying conditions from 1 day to another. To overcome these hurdles and to expose all cultivars homogeneously to the pest, an assessment method of cultivar resistance was developed under semi‐field conditions. In 2015, the resistance of 64 winter wheat cultivars to S. mosellana was assessed. Few or no larvae developed in the ears of resistant cultivars, but in susceptible cultivars, large numbers of larvae developed. Seventeen cultivars proved to be resistant, whereas 47 were susceptible. The identification of new resistant cultivars offers more opportunities to manage S. mosellana. The phenotyping method is easy, cheap, efficient and reliable. It can be used to guide the breeding of new resistant wheat cultivars. Using specific midge populations, this method could also be used in research on new resistance mechanisms in winter wheat or in other cereal species.     

New data on the distribution of hybrid necrosis genes in winter bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) cultivars

Hybrid necrosis genotypes have been identified in 125 Russian cultivars of winter bread wheat. More than half of them (56%) carry the Ne2 gene (genotype ne1ne1Ne2Ne2); others are free of necrosis genes (genotype ne1ne1ne2ne2). The possible causes of the increase in the Ne2 allele frequency and the loss of the Ne1Ne1ne2ne2 genotype in modern Russian cultivars of winter wheat are discussed. The principal component method has been used to compare the structures of the genetic diversity of cultivars differing in the hybrid necrosis genotype. It has been found that the Ne2 allele in winter wheat cultivars from northern Russia has originated from the cultivar Mironovskaya 808, whereas the cultivar Bezostaya 1 is not a source of this gene. In cultivars from southern Russia, the presence of the Ne2 allele is also mainly accounted for by the use of Mironovskaya 808 wheat in their breeding. The recessive genotype is explained by the presence of descendants of the cultivar Odesskaya 16 in the pedigrees of southern Russian winter wheats. The genetic relationship of cultivars with identical and different necrosis genotypes has been analyzed in nine regions of the Russian Federation.     

Effect of explant source and auxins on somatic embryogenesis of selected cassava (Manihot esculenta Crantz) cultivars

Competence for somatic embryogenesis of eight cassava cultivars T200, AR9-18, MTAI16, CR25-4, CM523-7, BRA1183, MCOL2261 and SM707-17 was compared to model cultivar TMS60444 in induction media containing 12 mg/l picloram or 8 mg/l 2,4-dichloro phenoxyacetic acid (2,4-D), using axillary buds (AB) and immature leaf lobes (ILL) as explants. There were significant differences (p < 0.01) among the cassava genotypes for ability to form somatic embryos (SE). In general, AB as the explant and picloram-containing medium had the highest frequency of SE for TMS60444, T200, MTAI16, CR25-4 and CM523-7 while AR9-18 had greater efficiency using ILL on picloram. Cultivars BRA1183, MCOL2261 and SM707-17 produced insignificant amounts of SE; however, loose callus and friable embryogenic callus (FEC) appeared to be the predominant tissue type observed. Five out of the eight cultivars studied showed capability of producing SE although their efficiency for somatic embryogenesis was not as high as the model cultivar TMS60444.     

Antibiosis and Non-preference of Sitobion avenae (F.) (Hemiptera: Aphididae) on Leaves and Ears of Commercial Cultivars of Wheat (Triticum aestivum)

Little is known on the resistance of wheat cultivars to Sitobion avenae (F.) in Brazil. The goal of this work was to assess the behavior and biology of S. avenae on four commercial wheat cultivars to verify the existence of resistance by antibiosis in leaves and ears and non-preference in the ears. The smallest net fecundity rates of S. avenae in wheat leaves have been found in the cultivars Embrapa 22 and BRS264, which did not differ between themselves. The intrinsic rate of increase of S. avenae was smaller in leaves of Embrapa 22 than in cultivars BRS254 and BRS Timbaúva. The smallest net fecundity rates of S. avenae in wheat ears were observed in the cultivars BRS254 and Embrapa 22. The intrinsic rate of increase of the aphid in the ear of cultivar Embrapa 22 was smaller than in BRS Timbaúva and BRS264, but did not differ from BRS254. The organ of the wheat plant in which the aphid was reared influences antibiosis resistance, but the cultivar BRS Timbaúva was considered susceptible and Embrapa 22 resistant to S. avenae in both plant organs tested. Ears of wheat cultivars tested did not show differences in the mechanism of resistance by non-preference to S. avenae.     

夏季苹果新梢生理指标与抗苹果绵蚜的关系

研究苹果生理指标与其对苹果绵蚜(Eriosoma lanigerum Hausmann)抗性的关系,为筛选培育抗性品种,实现持续有效治理苹果绵蚜提供依据.田间调查不同苹果品种对苹果绵蚜的抗性,测定比较各品种正常枝条生理指标,以及被苹果绵蚜危害后生理指标的变化.结果表明,正常枝条中可溶性糖(r=0.99)、蛋白质(r=0.86)含量与感蚜率呈正相关;氨基酸含量与感蚜率呈负相关(r=-0.96);酚类物质和4种酶活性与苹果感蚜率均不存在明显相关性.被害后昭锦108可溶性糖含量有所下降,红富士、金冠分别上升1.4％、7.0％;蛋白质、氨基酸、酚类物质含量均有所下降,其中红富士总酚含量明显下降,达23.5％,总酚下降率与感蚜率呈正相关(r=0.94);超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化氢酶(Catalase,CAT)活性均上升,其中CAT变化率与感蚜率存在相关性(r=-0.92),昭锦108 CAT活性明显上升,达91.2％;多酚氧化酶(Polyphenol Oxidase,PPO)、过氧化物酶(Peroxidase,POD)活性增减不一;金冠4种酶活性均上升.研究表明,对苹果绵蚜抗性较强的品种:可溶性糖、蛋白质含量较低,游离氨基酸含量较高;受害后可溶性糖含量下降,总酚含量下降率较低,游离氨基酸含量下降率较高.酶活性对抗蚜性的影响不明显.     

Molybdenum-induced alteration of fatty acids of thylakoid membranes contributed to low temperature tolerance in wheat

The fact that molybdenum (Mo) applications can alleviate low temperature stress (LTS) in plants has been widely reported, but the underlying mechanisms are not fully understood. The effects of Mo (0 and 0.15 mg kg^?1) on photosynthetic pigments, fatty acids and the chlorophyll–protein complex of wheat seedlings in pot culture were investigated at 0, 2, 4 and 6 days of LTS. Chlorophyll a and b, total chlorophyll and carotenoid contents were significantly enhanced by Mo application. The palmitic acid (C16:0) content and total saturated fatty acids (TSFA) were drastically decreased in wheat cultivar 97003 at 2 and 4 days of LTS and in wheat cultivar 97014 at 2 days of LTS. The linolenic acid (C18:3) content and total unsaturated fatty acids (TUSFA) were significantly increased in both cultivars at 2 and 4 days of LTS. The palmitoleic acid (C16:1) content was also drastically increased in cultivar 97003 at 2 days of LTS, suggesting that Mo induced a greater production of unsaturated fatty acids or the conversion of TSFA to TUSFA. The ratio of unsaturated to saturated fatty acids and the index of unsaturated fatty acids in the thylakoid membranes were enhanced with supplemental Mo, suggesting that Mo might improve the degree of unsaturation. However, no significant differences were observed in the chlorophyll–protein complexes between the +Mo and ?Mo treatments. These results indicated that the alteration of fatty acids induced by Mo application in the thylakoid membranes of wheat contributed to LTS tolerance.     

Genetics of Heading Time in Wheat (TRITICUM AESTIVUM L.). II. the Inheritance of Vernalization Response

The inheritance of vernalization response was studied in crosses involving four spring wheats (Sonora 64 (S), Pitic 62 (P), Justin (J) and Thatcher (T)) and three winter wheats (Blackhull (B), Early Blackhull (E) and Extra Early Blackhull (EE)).—All winter cultivars were highly responsive to vernalization, and Pitic 62 was the only spring cultivar whose time to heading was significantly accelerated following cold treatments. When vernalized and grown under long days, spring and winter cultivars became comparable in their heading response, indicating that cold requirement is the major attribute differentiating the heading behavior of true spring and true winter wheats.—Inheritance of growth habit in the F₁ generation of a five-parent diallel cross showed dominance of the spring character in all spring x winter crosses. Depending on the cross, one or two duplicate major genes governing growth habit were detected in F₂, F₃ and backcross generations grown in the field under long days in the absence of vernalizing temperatures. In some spring x winter crosses most of the variation in heading time among spring segregates could be attributed to the effects of major genes conditioning growth habit. In other crosses the heading patterns appeared more complex, indicating that genes with smaller effects are also involved in the control of heading response under spring or summer environments.—Evidence was presented supporting the hypothesis that the cultivar Pitic 62 carries a different allele at one of the two major loci governing its spring habit. This allele was associated with some response to vernalization and acted as a dominant gene determining earliness under low temperature vernalization, but as a partially recessive gene determining lateness in the absence of vernalizing temperatures. Genotypes were assigned to five cultivars as follows: S, CC DD; P, CC D'D'; J, cc DD; B and EE, cc dd.—The presence of major and minor genes and of multiple alleles governing response to photoperiod and vernalization was discussed in relation to the genetic manipulation of the heading response and to breeding wheat cultivars with specific or broad adaptation.     

WCS120 protein family and proteins soluble upon boiling in cold-acclimated winter wheat

The amount of proteins soluble upon boiling (especially WCS120 proteins) and the ability to develop frost tolerance (FT) after cold acclimation was studied in two frost-tolerant winter wheat cultivars, Mironovskaya 808 and Bezostaya 1. Protein gel blot analysis, mass spectrometry (MS) and image analysis of two-dimensional gel electrophoresis (2-DE) gels were used to identify and/or quantify the differences in protein patterns before (non-acclimated, NA) and after 3 weeks of cold acclimation (CA) of the wheats, when FT increased from -4 degrees C (lethal temperature (LT(50)), for both cultivars) to -18.6 degrees C in Bezostaya 1 and -20.8 degrees C in Mironovskaya 808. Only WCS120 protein was visible in NA leaves while all five WCS120 proteins were induced in the CA leaves. Mironovskaya 808 had higher accumulation of three members of WCS120 proteins (WCS120, WCS66 and WCS40) than Bezostaya 1. MS analysis of total sample of proteins soluble upon boiling showed seven COR proteins in the CA samples and only three COR proteins in the NA samples of cultivar Mironovskaya 808 (MIR). In conclusion, the level of the accumulation of WCS120, WCS66 and WCS40 distinguished our two frost-tolerant winter wheat cultivars. Moreover, the differences of CA and NA samples of the MIR were shown by liquid chromatography (LC)-tandem mass spectrometry (MS/MS).     

Seasonal variations in trans-2-hexenal and linolenic acid in homogenates of Thea sinensis leaves

The seasonal variations in the amounts of C₆-volatile components cis-3-hexenal trans-2-hexenal n-hexanal) and their precursors (linoleic and linolenic acid) in homogenates of Thea sinensis leaves were quantitatively analyzed throughout the year. Formation of trans-2-hexenal began in the middle of April and reached a maximum during July. Towards autumn the aldehyde gradually decreased and, in winter (December to March), was virtually absent. The levels of cis-3-hexenol remained constant during May–December. cis-3-Hexenal showed a similar variation pattern to that of trans-2-hexenal. The major fatty acids in the leaves were palmitic, palmitoleic, oleic, linoleic and linolenic acid, and occurred in non-ionic lipids and phospholipid fractions. The amounts of linoleic and linolenic acid did not show any marked variation except for a big peak in October.