THE EFFECT OF SUCROSE SPRAYING ON SYMPTOMS CAUSED BY BEET YELLOWS VIRUS IN SUGAR BEET

When leaves of sugar-beet plants infected with beet yellows virus were sprayed daily with 10% sucrose solution, yellowing symptoms were intensified. When glasshouse plants were shaded so that the light intensity was reduced to less than half of full daylight, yellowing symptoms were suppressed more completely on un-sprayed than on sprayed plants. Spraying with 2–5 % sucrose solution had similar, but slightly smaller effects.
Spraying with sucrose solution increased the carbohydrate content of the leaves, and the effects on symptom intensity and carbohydrate content were closely correlated. The regression coefficients of symptom score on total sugar content were nearly the same for shaded and unshaded plants. As the severity of symptoms was increased by supplying carbohydrate without change in the light conditions, it is concluded that light intensity affects symptom expression by varying the carbohydrate content of the leaves through its influence on photosynthesis.
Sucrose spraying increased the yield of roots of healthy and infected plants, and most of the increase was sucrose. This shows that sprayed sugar was translocated to the roots from the leaves of both healthy and infected plants.
Measurements of changes in carbohydrate content between evening and morning samplings confirmed that movement of carbohydrate out of infected leaves is not stopped by infection.     

甜菜夜蛾卵的超低温冷冻保存(英文)

通过对甜菜夜蛾卵超低温冷冻过程中一系列影响因子的研究 ,建立了甜菜夜蛾卵在液氮中冷冻保存的方法。结果表明 ,利用 1 5%次氯酸钠处理卵壳 6min ,再用异丙醇处理 1 5sec和N 己烷处理 30sec可有效去除甜菜夜蛾卵的外卵壳和蜡质层 ,获得 95%以上的渗透化率和 60 %左右的存活率 ;渗透化卵经 2mol L乙二醇初步抗冻 30min和含 1 0 %BSA的 8 5mol L乙二醇脱水 5min ,约有 55%～ 60 %的卵存活和2 4 %的卵孵化 ;将抗冻处理后的卵投入液氮 ( - 1 96℃ )中 2 4h ,在 37℃下解冻 ,结果有 ( 1 6 3± 7 6) %的卵发育至黑头期 ,( 1 6± 1 1 ) %的卵孵化。     

甜菜原生质体培养直接产生体细胞胚

甜菜(Beta vulgaris L.)是重要的经济植物,是制糖的重要原料。近10年来已相继有人开展了甜菜原生质体的培养,但到目前为止,在国内外还未有关于甜菜原生质体培养中体细胞胚发生的报道,尤其是从原生质体直接的发生。本研究从甜菜未授粉的胚珠诱导产生的愈伤组织制备原生质体,分裂后直接产生体细胞胚,现报道于下。用于分离原生质体的愈伤组织是从甜菜(Beta vulgaris L.)品系1804/6未授粉胚珠诱导产生的。将该愈伤组织在 MS 培养基附加1.0mg/L 2,4-D 0.5mg/L 6-BA 中     

CRYOPRESERVATION OF THE BEET ARMYWORM EGGS*

Abstract A protocol for cryopreservation of the eggs of beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) in liquid nitrogen was established after examining the effects of a number of factors on the survival of the eggs during various stages of cryopreservation. Over 95% of eggs incubated at 271) for 33 h were permeabilized and about 60% of them could hatch using the following permeabilization procedure: dechorionation of eggs in 15% sodium hypochlorite for 6 min followed by immersion in isopronol for 15 sec to remove surface water and then in n‐hexane for 30 sec to dissolve the wax layer. Immersion of the permeabilized eggs in 2 mol/L ethylene glycol for 30 min and then dehydration in 8.5 mol/L ethylene glycol solution containing 10% BSA for 5 min led to 55%? 60% survival and approximately 24% hatching rate. Eggs cryopreserved in liquid nitrogen using the recommended protocol have a survival rate of (16.3 ± 7.6)% and a hatching rate of (1.6 ± 1.1)%.     

THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR-BEET ROOT CROP I. FIELD OBSERVATIONS ON THE VIRUS DISEASES OF SUGAR BEET AND THEIR VECTORS MYZUS PERSICAE SULZ. AND APHIS FABAE KOCH

A survey of aphids and virus diseases of sugar-beet root crops in eastern England was made between 1940 and 1948. Prior to 1943 the observations were made on fertilizer experiments; from 1943 onwards they were made on commercial fields selected for position in relation to beet and mangold seed crops. The incidence of beet yellows increased with increasing numbers of Myzus persicae , but not of Aphis fabae. The relation with M. persicae was sufficiently close to suggest that it is the most important, possibly the only important, vector of beet yellows virus. Beet mosaic virus also increased with increasing numbers of M. persicae , but the relation was not close enough to exclude the possibility of other vectors.
Numbers of A. fabae on sugar beet were slightly, but consistently, depressed by the use of salt as a fertilizer. Other fertilizers had variable effects. Neither aphids nor virus are likely to be greatly affected by fertilizers.
Beet yellows is most prevalent in areas where seed crops are grown, but within these areas nearness to individual seed crops did not appear to increase its incidence. M. persicae were more numerous on sugar beet in seed-crop areas than elsewhere, and this alone might account for the prevalence of yellows. Beet mosaic virus is more closely associated with seed crops than is beet yellows. It is most prevalent near to seed crops within the seed-crop areas.     

APHID BEHAVIOUR ON HEALTHY AND ON YELLOWS-VIRUS-INFECTED SUGAR BEET

Myzus persicae Sulz., M. ascalonicus Doncaster, Aphis fabae Scop, and Aulacorthum solani Kalt., when caged on sugar-beet leaves in the glasshouse preferred yellows-virus-infected leaves to healthy ones; they chose those with the most severe symptoms on which they bred more rapidly and lived longer than on green leaves. M. persicae behaved similarly on whole plants in the glasshouse. The previous host influenced the aphid's preference. Differences between the multiplication rates of aphids on healthy plants of inbred sugar-beet varieties were eliminated or reversed by infection with yellows virus.
Spraying healthy plants with either sugar solutions or hydrolysate of casein increased the multiplication rate of M. persicae , but much less than did virus infection.     

THE EFFECT OF INFECTION WITH BEET YELLOWS AND BEET MOSAIC VIRUSES ON THE CARBOHYDRATE CONTENT OF SUGAR-BEET LEAVES, AND ON TRANSLOCATION

The loss of total carbohydrate (sugars and starch) per cent of residual dry matter (dry matter less total carbohydrate) during a period of darkness from leaves of sugar-beet plants infected with yellows virus was as great as that from the leaves of healthy plants. The conclusion of previous workers, based on the results of the Sachs iodine test for starch and the occurrence of 'phloem gummosis' in infected plants, that starch accumulates in infected leaves because translocation is prevented by blockage of the sieve-tubes, is therefore incorrect.
Older leaves of infected plants had a higher content of reducing sugars and sucrose, and usually but not invariably of starch, both at the beginning and end of the dark period, than comparable leaves of healthy plants. By far the greater part of the increase was in reducing sugars. In leaves taken in late September from infected plants growing in the field, 20 % or more of the total dry matter was present as reducing sugars. The reducing sugars in both healthy and yellows-infected leaves were shown by paper chromatography to be glucose and fructose in approximately equal amounts.
Accumulation of carbohydrate in infected leaves is probably not a passive consequence of differences in carbohydrate production, distribution and utilization, but is attributable to changes in the physiology of the cells of the leaf.
The carbohydrate content of sugar-beet leaves was little affected by infection with beet mosaic virus.
Yellows-infected leaves had a lower water content per cent of fresh weight than healthy leaves. This was accounted for by the higher carbohydrate content of infected leaves, for the ratio of water: residual dry matter was not affected by infection or was slightly reduced. This implies that hydration was independent of carbohydrate content.     

ULTRASTRUCTURAL FEATURES OF BETA LEAVES INFECTED WITH BEET YELLOWS VIRUS

A cytochemical and electron microscope study has been made of leaves of sugar beet infected with beet yellows virus. Inclusions of particles, which agree in size with beet yellows virus particles isolated by other investigators, have been localized in the ground cytoplasm, in the chloroplasts, and in the nuclei. These particles are circa 100 A in diameter and have an electron-transparent core of 30 to 40 A. Use of acridine orange, azure B, and pyronine Y has revealed that the cytoplasmic inclusion bodies, which consist wholly of the elongate particles, have a strong RNA reaction removable by RNase pretreatment. Particles observed in the chloroplasts may or may not be associated with lipid spheres. If they are, the particles are confined to the periphery of the spheres. In this position the particles are arranged tangentially and are further arranged parallel into groups which lie at various angles to one another. Within the groups the particles are regularly spaced in a three dimensional lattice. Particles located free in the stromal regions are often arranged regularly in curved rows which lie parallel to one another so that a three dimensional lattice is formed. The dispersed and compact forms of virus inclusions are described and related to the condition of the associated cytoplasm. The ground cytoplasm of cells associated with the sieve elements contains numerous ribosomes. A decrease in the number of ribosomes is concomitant with the increase in size of virus aggregations in a cell. Vesiculation of some component of the cytoplasm occurs during the period of virus replication. The vesicles are approximately 100 mµ in diameter and could be derived from the dictyosomes. At later stages of infection these vesicles collapse and convoluted membranous material appears.     

THE EFFECT OF MANURES ON THE BOLTING OF THE BEET PLANT

In sugar beet, the effect on bolting of additions of potash manures, of superphosphate, and of the mixture of these was not significant, whether applied at the time of sowing or previously. Dung applied in the previous autumn slightly increased the number of plants which went to seed, and when applied just before sowing it had a more marked effect. An amount of sulphate of ammonia which would have approximately the same stimulating effect as the dung gave a slightly larger amount of bolting.
On red beetroot, it was possible to compare larger and smaller dressings of various coarse organic manures, and of each of these with and without dressings of sulphate of ammonia. In all cases the sulphate of ammonia and each of the organic manures largely increased the amount of bolting, and a doubling of the organic manure dressing or the addition of sulphate of ammonia to it caused a further increase. Sewage sludge gave an abnormally large amount of bolting, but it is doubtful whether this was due to the larger amount of organic matter and nitrogen applied in this manure. In general, any manurial addition causing more vigorous growth leads to an increase in bolting. There is a very large variation in the amount of running to seed in the crop of red beetroot from different parts of the same field, but the effect of the manures on the proportion which bolted was not widely different.
The general question as to the reason why beet plants should bolt more in one season than in another is discussed, and it is suggested that a check to the plants in an early stage, whether caused by dryness or waterlogging, or by low temperature, followed by a vigorous growing period may have something to do with the matter. This would agree with the experiences recorded in the present paper.