根系分泌物在西瓜/旱作水稻间作减轻西瓜枯萎病中的响应

采用盆栽的方法,研究了西瓜/旱作水稻间作对西瓜枯萎病和西瓜根系分泌物中酚酸、氨基酸、有机酸种类和含量的影响。结果表明:与对照相比,接种西瓜专化型尖孢镰刀菌(Fusarium oxysporun f.sp.niveum,FON)显著提高了西瓜根系分泌物中酚酸的含量,增加了酚酸的种类如香豆酸,当西瓜/旱作水稻间作时,大部分酚酸的分泌量降低。在接种FON的条件下,西瓜/旱作水稻间作较单作显著降低西瓜根系分泌物中酚酸含量。与对照相比,接种FON提高了西瓜根系分泌中氨基酸的含量,而在西瓜/旱作水稻间作条件下接种FON时,西瓜根分泌物中氨基酸含量没有变化。与对照相比,接种FON显著提高了西瓜根系分泌有机酸的量,当西瓜/旱作水稻间作时,大部分有机酸分泌量降低。在接种FON的条件下,西瓜/旱作水稻间作较单作降低了西瓜根系分泌物中有机酸含量。总之,接种FON提高了西瓜根系分泌酚酸、氨基酸和有机酸的量,西瓜/旱作水稻间作降低西瓜枯萎病发病率和发病指数,并维持西瓜根系分泌酚酸、氨基酸和有机酸的量不增加,因此,西瓜/旱作水稻间作减轻西瓜枯萎病与西瓜根分泌物的调节有关。     

百合抗尖孢镰刀菌无性系的离体筛选

以百合品种元帅(Acapulco)、卡萨布兰卡(casablanca)的愈伤组织为试验材料,附加不同浓度的枯萎病菌毒素粗提液,用于抗尖孢镰刀菌无性系的离体筛选.结果表明,以体积分数75%的毒索培养基上培养10d作为百合抗尖孢镰刀菌无性系筛选的选择压比较适宜,抗镰刀菌无性系的再生苗生长正常,叶片中过氧化物酶(POD)、多酚氧化酶(PPO)、超氧化物歧化酶(SOD)活性均比未经筛选的对照株高,经人工接种枯萎病菌鉴定,2个百合品种抗尖孢镰刀菌无性系的再生植株均表现中抗枯萎病.     

抗青枯病花生资源的种子大小 及主要品质性状的遗传分化

以123份不同类型的抗青枯病花生种质为材料,对荚果大小、种子大小、出仁率、蛋白质、含油量和脂肪 酸等性状遗传分化进行了研究。研究结果表明,在我国抗青枯病花生资源中,高油酸种质资源较多,这些资源的荚 果及种仁大小,油酸、亚油酸、棕榈酸、硬脂酸、花生酸、花生烯酸、山嵛酸含量性状均存在丰富的遗传变异;但是,高 含油量资源较少,而且在含油量、蛋白质含量和出仁率方面的遗传多样性不丰富。根据12个与种子品质相关性状 信息, 123份抗青枯病资源被分成2组5亚组13个品种群,这些品种(群)与已被广为利用的骨干抗病亲本协抗青 和台山三粒肉之间存在很大的遗传分化。     

Correlation of molecular markers and biological properties in Verticillium dahliae and the possible origins of some isolates

Haploid and amphihaploid Verticillium dahliae isolates were studied using PCR-based molecular markers which: (i) discriminate the defoliating and nondefoliating pathotypes (two primer pairs INTD2f/r and INTND2f/r), and (ii) are species-specific (primer pair 19/22). The results were compared with some known biological and other molecular properties of the isolates. Five discrete sequences of the 19/22 amplicon were found. Sequence 4 was associated with both defoliating isolates from Spain and nondefoliating isolates from Spain and USA; these pathotypes were separated by the primer pairs INTD2f/r and INTND2f/r, but the data showed that the primer espdef01 (derived from the 19/22 amplicon) cannot be used for this purpose. Amplicon sizes and sequences with primers 19/22 divided amphihaploid isolates from crucifers (thought to be interspecific hybrids) into those corresponding to the previously reported α and β groups. The β-group isolates had either sequence 4 or 5 (these two differing by a single base). The distinct amplicon sequence 3 given by the α-group isolates demonstrated that the V. dahliae -like 'parent' of this group was molecularly unlike any haploid isolate yet studied. The overall results are discussed in relation to phytosanitary considerations and the probability of defoliating or crucifer pathotypes arising de novo within Europe, either by selection or by interspecific hybridizations.     

Effects of plastic mulches on root zone temperature and on the manifestation of tomato spotted wilt symptoms and yield of tomato

Tomato spotted wilt (TSW) disease is a serious constraint to tomato production in various regions of the world. The effect of TSW on tomato yield is largely influenced by time of infection. Early infection usually results in severe stunting of the seedling and even death of the plant. Plastic film mulches affect both the incidence of TSW, and plant growth and yield of tomato. The objective of the present study was to determine the effect of root zone temperature (RZT) as affected by plastic film mulch on the manifestation of symptoms of TSW, and growth and yield of tomato plants either artificially inoculated with tomato spotted wilt virus (TSWV) or under natural TSW infection. In artificially inoculated plants as well as in plants under natural TSW infection, vegetative top fresh weight (FW) and fruit FW both increased with the length of time after transplanting that the plants remained free from TSW symptoms. The root zone temperature was highest under black mulch (seasonal mean = 27.5 °C), followed by gray (27.0 °C), silver (25.8 °C), and white (24.8 °C) mulches. The plants grown on black mulch showed the earliest appearance of TSW symptoms, and had significantly reduced vegetative growth and fruit yields compared to plants on the other mulches. In conclusion, utilization of plastic mulches that created conditions of high RZT stress resulted in reduced plant growth and yield and predisposed the plants to earlier expression of TSW symptoms compared to plants grown at RZTs more favorable to tomato plant growth (optimal RZT = 26.1 °C [Díaz-Pérez, J.C., Batal, K.D., Granberry, D., Bertrand, D., Giddings, D., Pappu, H., 2003. Vegetative top growth and yield of tomato grown on plastic film mulches as affected by the appearance of symptoms of Tomato spotted wilt virus. HortScience 38, 395–399]). Since these plant responses to TSW under heat stress occurred in artificially inoculated plants as well as in plants under natural TSW infection, high RZTs probably affected the plants directly, independently of any possible effects on the thrips vectors.     

无籽西瓜嫁接效应研究

在湖北荆州采用靠接法和顶插接法对郑抗无籽5号、郑抗无籽6号、黑元帅、黑将军等4个无籽西瓜品种进行了嫁接育苗与栽培效应研究。结果表明:采用嫁接栽培的西瓜显著降低了枯萎病的发病率、病情指数及病死株率,产量显著提高;采用靠接法的嫁接苗成活率和单果重显著高于顶插接法;采用顶插接果实中心可溶性固形物含量有提高的趋势;嫁接西瓜口感与自根西瓜无明显差异。郑抗无籽5号、6号的综合表现较优。     

Two in vitro assays to evaluate resistance in Linum usitatissimum to Fusarium wilt disease

Two types of in vitro seedling tests were developed to evaluate resistance in flax (Linum usitatissimum) against Fusarium oxysporum f.sp. lini. In the first test a solid medium was used. The second test was based on a liquid medium. Disease severity was assessed after three weeks, using the observed reduction of plant length as a scale. Both methods proved to be useful for screening for resistance, for evaluating race specificity of resistance and for studying symptomatology. The solid medium method proved to be the more accurate for the screening, but the liquid medium method was much less time- and labour-consuming. The results of the tests were significantly correlated with observations under field conditions.     

木霉菌对甜瓜枯萎病的防治

研究木霉菌T23、Ta22菌株对甜瓜枯萎病菌的拮抗作用和T23、Ta22二者复合处理对甜瓜枯萎病的室内及田间防治效果,结果表明：T23与Ta22对枯萎病菌拮抗系数都很高,二者复合处理对甜瓜枯萎病的田间相对防效可达79．00％。     

Evaluation of Olive Cultivars for Resistance to Verticillium dahliae

Resistance of 23 important olive cultivars to Verticillium dahliae has been evaluated in four experiments under controlled conditions. Nine-month-old nursery olive plants were inoculated with a cotton non-defoliating (ND) (V4) or a cotton defoliating (D) (V117) isolate of V. dahliae. Resistance was evaluated by assessing symptom severity using a 0–4 rating scale and estimating the area under disease progress curves. The percentage of plants killed and of those which recovered from the disease were used as additional parameters for including a particular cultivar into a defined category. Most of the evaluated cultivars were susceptible, although at different levels, to both isolates of V. dahliae. All cultivars were more susceptible to the D pathotype than to the ND one. A group of 11 cultivars, including several important Spanish cultivars, were susceptible or extremely susceptible to both pathotypes of V. dahliae. A second group showed differences of resistance depending on the pathotype used. They were susceptible or extremely susceptible to the D pathotype but resistant or moderately susceptible to the ND one. Finally, 'Frantoio', 'Oblonga' and 'Empeltre' were moderately susceptible to the D isolate of V. dahliae and resistant to the ND one. The resistance of 'Empeltre' was evident by the plant ability to recover from infection with either isolates. 'Empeltre' is considered to be a valuable cultivar for inclusion in breeding programmes for resistance to Verticillium wilt.