Identification and Validation of Molecular Markers Associated with Pachymetra Root Rot and Brown Rust Resistance in Sugarcane Using Map- and Association-based Approaches

Marker-assisted selection for traits that are difficult to screen for, such as resistance to many sugarcane diseases, has the potential to facilitate the development of improved cultivars in sugarcane. Pachymetra root rot (PRR) and brown rust resistance ratings were obtained over two years for 192 I1 progeny (progeny produced by two heterozygous, non-inbred parental lines) of a sugarcane (Saccharum spp. hybrid) cross between two elite sugarcane clones, Q117 and 74C42. Approximately 1000 single-dose markers, including microsatellite (SSR), amplified fragment length polymorphism (AFLP) and restriction fragment length polymorphism (RFLP) markers, were scored across the population and maps containing approximately 400 markers were constructed for each parent. At p ≤ 0.01, two genomic regions, one from the female Q117 map and a different region from the 74C42 male map, plus an unlinked bi-parental simplex marker (single-dose marker present in both parents) were identified as associated with PRR over both years of data collection. These regions explained between 6 and 16% of the phenotypic variation. An additional region was identified in the female map as associated with PRR at p ≤ 0.01 in one year and p ≤ 0.05 in the second year. This region explained between 4 and 8% of the phenotypic variation. For brown rust, two genomic regions, one from the female map and one from the male map, plus an unlinked marker from both maps, were identified as associated with brown rust resistance at p ≤ 0.01 over two years of phenotypic data. Each region explained between 7 and 18% of the phenotypic variation. Several additional regions were identified in both maps as associated with brown rust at p ≤ 0.01 in one year and p ≤ 0.05 in the second year. These regions also explained between 5 and 11% of the phenotypic variation. To validate these markers and determine whether they would be useful in alternative germplasm, markers from each genomic region associated with PRR or brown rust were screened across a set of 154 elite sugarcane clones; PRR and brown rust ratings were available for 131 and 72 of the clones, respectively. For PRR, three of the 6 markers tested remained significantly associated (p ≤ 0.01) with resistance ratings in the elite clone set. For brown rust, only one of the seven markers tested remained significantly associated (p ≤ 0.01) with resistance in the elite clone set, with one other marker associated at p ≤ 0.05. These results suggest that these markers could be broadly effective in selecting for PRR and/or brown rust resistance in sugarcane breeding programs.     

不同摇瓶条件对侧耳菌生长及漆酶分泌的影响

研究了小试液体摇瓶下不同pH培养条件、摇瓶转速、装液量对侧耳属白腐菌BP漆酶分泌及生长状况、形态变化的影响。结果表明：BP在中、酸性条件下生长较好且表现较高的分泌漆酶能力,用硫酸调pH为5．0时,漆酶活力和生物量分别在第10d和第6d达到最高,分别为742U／mL和8．4g(干重)/L,高于相应缓冲液调节pH体系的结果;天然(pH6．5)培养条件下,最佳转速与装液量分别是150r／min、200mL/500mL三角瓶,此时菌球较小,四周为毛刺状,漆酶酶活和生物量分别在第5d和第6d达到最高,分别为714．2U／ml和9．2gtL。同时,运用SPSS统计软件对各影响因素进行差异显著性检验,获得白腐菌生长及漆酶分泌特性的主要影响因子。     

Affinity purification of a siderophore that exhibits an antagonistic effect against soft rot bacterium

Bacterial colonies were isolated from different Egyptian soil samples. From these isolates, one bacterial species was found to produce siderophore. Using classical and biochemical identification methods, the siderophore producing isolate was identified as Pseudomonas fluorescens. Based on the affinity of siderophores for metal ions, an affinity chromatography system was designed for the purification of the siderophore in one step. It was possible to isolate 25 mg siderophore per liter of culture media. The purified siderophore was found to exist in two forms of approximately 30 and 90 kD. They are believed to be polymers of several siderophore molecules. Both forms were found to be active against the pathogen Erwinia carotovora var. carotovora, the causal bacteria of soft rot disease on potato tubers. The advantage of this method over other purification methods is that it uses metal ion so it can be applied for the purification of the known types of siderophores. Moreover, the purification is based on affinity chromatography, so the siderophore purity state permits several biotechnological applications without further treatments.     

猕猴桃间座壳菌Diaporthe actinidiae的绿色荧光蛋白基因标记及侵染过程

果实软腐病是猕猴桃贮藏期间最严重的真菌病害,猕猴桃间座壳Diaporthe actinidiae是该病检出率最高且致病力最强的病原菌.该病菌从花前期开始侵染,至果实贮藏期才表现症状,侵染至发病周期较长,可借助荧光标记对其侵染过程进行研究.本研究采用PEG介导原生质体转化的技术,运用携带GFP及潮霉素抗性基因的双元载体p...     

Seeds as Vehicles for Pathogen Importation

Since the 1900s, consumer demand for new plant products gave opportunity for many plant pathogens to disseminate to new areas on imported seeds. New markets for plant commodities encouraged plant breeders to begin collecting seed stocks from abroad. The birth of new seed companies extend their markets to new area. These events began the global dissemination of many seedborne pathogens. Many seedborne pathogens gained entry and escaped detection by specific traits that favored their dissemination. Three recent case scenarios are presented that illustrate how plant pathogens that passively employ the seed coats of their host achieved global dissemination and permanence in each patho-system. Evidence is presented to show that asparagus (Asparagus officinalis) seed produced in the US acted as a vehicle for disseminating one vegetatively compatible group (VCG) of a pathogenic fungus on asparagus called Fusarium proliferatum throughout new plantings in Australia. Similarly, public demand for Mediterranean cuisine in the US and abroad during the last 20 years led to an increase in the importation of basil (Ocimum basilicum) seed along with an inconspicuous fungus called Fusarium oxysporum. The fungus caused a destructive disease called Fusarium wilt of basil that appeared in over 25 separate locals spanning three continents. The third example demonstrated how new developments in lupine (Lupinus spp.) cultivars and increased public demand led to the global dispersal of a seedborne pathogen called Colletotrichum gloeosporioides. Each case highlights how these pathogens use seeds, humans, and particular traits to disperse globally in short period of time.     

Mycotoxins in potato tubers infected by<Emphasis Type="Italic">Fusarium sambucinum</Emphasis>

Potato tubers artificially infected withF. sambucinum were contaminated with diacetoxyscirpenol in concentrations up to 200 μ/tuber. The toxin could also be found in tubers without any disease symptoms. The duration of storage and an increased temperature raised toxin production in infected tubers. Susceptibility of potato cultivars towardsF. sambucinum was well correlated with toxin levels. The concentration of diacetoxyscirpenol in the susceptible cultivar was five times higher compared to the more resistant one. The toxin could not only be found in rotten tuber tissue but also in distant healthy looking parts. There is a gradient in toxin concentrations showing a strong decline with an increasing distance from the infection point. Tissue being 10–15 mm far from the diseased area contained up to 110 μg/kg. Consumers should pay attention to the fact that cutting out the diseased tissue may be not sufficient enough to prevent the intake of mycotoxins.     

Conidioma production of the white root rot fungus in axenic culture under near-ultraviolet light radiation

 Conidiomata of the white root rot fungus were produced in axenic culture under near-ultraviolet light radiation. Pieces of sterilized Japanese pear twigs were placed on 7-day-old oatmeal agar culture in plates. The plates were further incubated for 5 days and then illuminated by near-ultraviolet light. Synnemata developed on the twigs within 5 weeks in 19 of 20 isolates tested, and conidia were observed in 12 of the 19 isolates. The synnemata and conidia produced were morphologically identical to those of Dematophora necatrix. Received: October 29, 2001 / Accepted: March 11, 2002     

抗菌肽基因转化大白菜获得抗病转基因植株及稳定遗传

软腐病是大白菜 (BrassicapekinensisRupr.)的三大病害之一。抗菌肽对软腐病菌有很强的杀伤作用。建立了根癌土壤杆菌 (Agrobacteriumtumefaciens)EHA10 5 (pMOG4 10 )工程菌的高频转化载体系统 ,将抗菌肽基因导入目前推广种植的大白菜AB_81自交系 ,获得了转基因植株。PCR及Southernblotting分子杂交鉴定表明抗菌肽基因已整合到白菜基因组。转基因植株提取液的体外抑菌实验、试管苗及盆栽转基因植株的病原菌接种抗病测试结果表明转基因植株具有明显的抗病特性 ,并且能稳定遗传 ,转基因植株R1自交分离比为 3∶1,R5的转基因植株保持抗Km和抗病特性 ,可望以其为亲本选育出大白菜抗软腐病的新品种。     

Detection of genetic variation among single-spore isolates and identification of genets ofArmillaria ostoyae by AFLP analysis with Texas RedTM-labeled selective primer

AFLP (amplified fragment length polymorphism) analysis was applied toArmillaria ostoyae isolates (single-spore isolates and field isolates from the same forest). For detection of AFLP, we have developed a modified method using DNA sequencer with Texas Red-labeled selective primer. In analysis of single-spore isolates, this technique provided large numbers of highly polymorphic DNA markers, which can be used to identify genets. The results suggested that outbreeding might be common inA. ostoyae.