Detection of the Defoliating Pathotype of Verticillium dahliae in Infected Olive Plants by Nested PCR

Spread of Verticillium wilt into newly established olive orchards in Andalucía, southern Spain, has caused concern in the olive industry in the region. This spread may result from use of Verticillium dahliae-infected planting material, which can extend distribution of the highly virulent, defoliating (D) pathotype of V. dahliae to new areas. In this study, a molecular diagnostic method for the early in planta detection of D V. dahliae was developed, aimed especially at nursery-produced olive plants. For this purpose, new primers for nested PCR were designed by sequencing a 992-bp RAPD marker of the D pathotype. The use of the specific primers and different nested-PCR protocols allowed the detection of V. dahliae pathotype D DNA in infected root and stem tissues of young olive plants. Detection of the pathogen was effective from the very earliest moments following inoculation of olive plants with a V. dahliae pathotype D conidia suspension as well as in inoculated, though symptomless, plants.     

欧洲卫矛嫁接技术

以欧洲卫矛为试验材料,研究了接穗粗度、嫁接季节和嫁接方法、嫁接切口绑扎方式不同处理对欧洲卫矛嫁接成活率的影响。结果表明:欧洲卫矛嫁接的最佳接穗粗度为0.55~0.60 cm,成活率可达83.84%;嫁接最佳季节为秋季,最佳嫁接方式为切接,秋季切接是最好的嫁接处理组合,成活率达到87.88%;用塑料薄膜绑扎切口后再用塑料袋罩住嫁接切口的欧洲卫矛嫁接成活率为83.95%,高于其他绑扎方式。     

Phytophthora oleae,a new root pathogen of wild olives

Wild olive (Olea europaea subsp. europaea var. sylvestris) is an important component of Mediterranean forests and a key genetic source for olive improvement programmes. Since 2009, a severe decline caused by Phytophthora cryptogea and P. megasperma has been detected in a protected wild olive forest of high ecological value (Dehesa de Abajo, Seville, Spain). In this natural forest, sampling of roots and soil was carried out on 25 wild olives with symptoms in 2014 and 2015. Apart from the already known P. cryptogea A1 and P. megasperma, a third Phytophthora species was consistently isolated from wild olive rootlets with symptoms. These isolates conformed morphologically with the newly described species P. oleae and were confirmed by analysis of their ITS regions and cox1 sequences. Temperature–growth relationships showed a maximum growth at 19.9 °C on carrot agar medium, making it the lowest temperature Phytophthora species infecting wild olive roots. Pathogenicity was confirmed on 1-year-old healthy wild olive seedlings and was similar to the previously known pathogenic phytophthoras. As temperature requirements are quite different, the three Phytophthora species may be active against wild olive roots in different seasons. However, the prevalence of P. oleae infecting wild olives in recent years could be due to its introduction as a new invasive pathogen. The probable invasive nature of P. oleae, together with increasing rain episodes concentrated in short periods frequent in southern Spain, would allow the outbreak of infections in wild olive forests, and also put cultivated olive orchards at risk.     

Identifying the location of olive fruit abscission

For high quality oil, table olive characteristics, and reduction of alternate bearing tendencies, it is often desirable to harvest olive fruits prior to full physiological maturity, that is, before the natural separation zone has differentiated. Olive fruit abscission can occur at different positions, mainly fruit-pedicel, pedicel rachis and peduncle-branch, apparently varying according to cultivar, fruit weight, and fruit maturation. Precisely identifying the location of separation is critical for studying the differentiation of the abscission zone or zones and testing the effectiveness of harvest procedures, including the mode of action of different fruit-loosening chemicals. We determined the olive fruit abscission zone position under natural conditions, throughout the complete fruit maturation period, for two cultivars differing in fruit size. The major separation zone for the cultivars studied was between the fruit and pedicel. For cv. Picual, abscission in zones other that fruit-pedicel occurred in less than 15% of the fruit at all dates throughout the maturation period, whereas in cv. Hojiblanca, the percentages of fruits detached at peduncle-shoot (27%) and pedicel-rachis (19%) were initially substantial, and then decreased progressively during fruit maturation. Our data clearly indicate both varietal and temporal differences which should be taken into account not only when testing fruit-loosening compounds but in extrapolating test results to different varieties or dates. Fruit weight did not appear affect the abscission location. The method we used, of counting the different detached units, is simple and effective for determining the position of fruit abscission.     

油橄榄的早实丰产栽培技术

在调查、总结四川省油橄榄栽培历史、种植技术及其试验研究成果的基础上,从品种选择,种植地选择,整地、造林,栽植后的土、肥、水管理,整形、修剪,病虫害防治等方面系统地介绍了四川省发展油橄榄的早实丰产栽培技术。     

不同覆盖方式对云南干热河谷油橄榄园土壤温度、水分和容重的影响

对云南省金沙江干热河谷永仁地区油橄榄园地进行覆盖试验,研究了不同材料覆盖后油橄榄园土壤温度、水分、容重变化。结果表明,覆盖对土温变化的调节作用主要表现在土壤表层,随土层深度增加调节作用减小;夏季油橄榄园覆盖后随气候温度升高土壤温度日变幅减小;不同材料覆盖间存在差异,薄膜覆盖土温变幅最大,纸箱次之,秸秆变幅最小。覆盖提高了园地土壤含水量,有较好的保墒效果;覆盖秸秆、杂草0~20cm土层含水量较高;随着土壤深度增加,不同覆盖处理之间土壤水分含量差异增大。4种材料覆盖均有利于降低土壤容重,其中以秸秆效果最显著。     

盐生植物盐角草同化枝不定芽的诱导与增殖

【目的】建立并确定盐生植物盐角草(Salicornia europaea L)同化枝不定芽诱导与增殖的试验体系和培养基。【方法】以MS为基本培养基,通过附加不同浓度激素(TDZ、NAA、6-BA)及盐(NaCl)进行盐角草不定芽的诱导,筛选诱导盐角草不定芽的最适激素配比及盐浓度;后期通过对细胞分裂素TDZ浓度(0、1.6、1.8、2.0和2.5 mg/L)的摸索,确定盐穗木不定芽增殖的最适浓度。【结果】盐角草同化枝在含有200 mM NaCl的MS₃(2.0 mg/L TDZ、0.1 mg/L NAA)培养基中不定芽诱导率达32.4%,显著高于(P<0.05)其余组,为最适诱芽培养基。再生的不定芽在含有2.0 mg/LTDZ的培养基中经过30~40 d的培养,不定芽增殖率可达619.5%。盐角草不定芽诱导及增殖最适培养基均为:MS+2.0 mg/L TDZ+0.1 mg/L NAA+200 mM NaCl。【结论】一定浓度的TDZ、NAA及NaCl组合,可通过直接器官发生途径有效诱导盐角草同化枝不定芽的产生和增殖。     

Protection of olive planting stocks against parasitism of root-knot nematodes by arbuscular mycorrhizal fungi

The effects were investigated, under controlled conditions, of single and joint inoculation of olive planting stocks cvs Arbequina and Picual with the arbuscular mycorrhizal fungi (AMF) Glomus intraradices , Glomus mosseae or Glomus viscosum , and the root-knot nematodes Meloidogyne incognita and Meloidogyne javanica , on plant performance and nematode infection. Establishment of the fungal symbiosis significantly increased growth of olive plants by 88·9% within a range of 11·9–214·0%, irrespective of olive cultivar, plant age and infection by M. incognita or M. javanica . In plants free from AMF, infection by Meloidogyne spp. significantly reduced the plant main stem diameter by 22·8–38·6%, irrespective of cultivar and plant age. Establishment of AMF in olive plants significantly reduced severity of root galling by 6·3–36·8% as well as reproduction of both Meloidogyne spp. by 11·8–35·7%, indicating a protective effect against parasitism by root-knot nematodes. Infection by the nematodes influenced root colonization by AMF, but the net effect depended on the AMF isolate–olive cultivar combination. It is concluded that prior inoculation of olive plants with AMF may contribute to improving the health status and vigour of cvs Arbequina and Picual planting stocks during nursery propagation.     

Microsatellite markers based assessment of genetic diversity in Iranian olive (Olea europaea L.) collections

To study the genetic variation in Iranian olive collections and some foreign olive cultivars, 47 accessions of 18 local cultivars from 6 olive collections of Iran (Roudbar, Zanjan, Ahvaz, Dezful, Kazeroon and Shiraz), were analyzed along with 30 imported cultivars using 16 microsatellite primer pairs. All the used microsatellite loci revealed polymorphism in the studied genotypes, except GAPU14 and GAPU113 markers. Fourteen microsatellite primers amplified 126 polymorphic alleles in the 87 selected olive accessions. The average number of alleles per locus was 9, ranging from 3 to 14. Polymorphic information content (PIC) was 0.85. The genetic similarity based on Jaccard coefficient ranged from 0.15 to 1. The genetic relationships among accessions were investigated using cluster analysis and principal component analysis (PCA). Most of the accessions with the same name were grouped together; some exceptions were also observed. As expected, close relationship was observed among accessions within same cultivar. Most of the Iranian olive accessions were clustered to a main distinct group. Two-dimensional scatter plot of principal component analysis revealed a clear separation of most of the Iranian olives from Syrian and other introduced cultivars. These suggest that Iranian cultivars have different origin related to West Mediterranean basin cultivars and have evolved independently from the others. Between and within Iranian and foreign cultivars (cultivars including three or more accessions) genetic diversity was analyzed using analysis of molecular variance (AMOVA). AMOVA revealed higher within cultivar genetic variation (62.76%) as compare to that between cultivar variations (37.24%). The intra- and inter-cultivar variance tested by permutation test showed significant genetic variation at both levels. The high level within cultivar genetic variance could be due to mislabeling and presence of homonyms in cultivars produced by vegetative propagation from original plants.     

三个油橄榄品种花芽分化和果实发育过程观测

为研究油橄榄在酸性土壤、夏雨型气候环境下的生长发育特征,因地制宜开展田间栽培管理提供科学依据。以中国南方3个油橄榄适生良种豆果、柯基和尼Ⅰ为材料,比较花芽分化、花期物候、花序特征、单果重和含油率差异。结果显示:3个品种的花芽分化均起始于3月上旬,豆果和尼Ⅰ初花期为5月3日,花期分别为10、6 d;柯基初花期为5月4日,花期11 d。豆果、尼Ⅰ、柯基的平均花序长度分别为2.5、2.5、2.9 cm,单个花序平均小花数量分别为16.3、14.9、17.9个。果实转色的先后次序和成熟期的早晚一致,依次为尼Ⅰ、豆果和柯基;单果重和含油率随着时间的推移均呈上升趋势,但二者增速不同,单果重在果实发育前期增长较快,含油率在果实发育后期增长较快。至10月24日果实成熟度分别达M5(尼Ⅰ和豆果)和M4(柯基),尼Ⅰ的单果重和含油率分别为3.40 g、13.05%,豆果的单果重和含油率分别为1.15 g、14.31%,柯基的单果重和含油率分别为0.77 g、12.31%。综上表明,3个品种花期基本一致,柯基的花量大、花期长,可作为授粉品种加以利用;在果实的生长发育过程中,前期应加强田间肥水管理,以确保树体处于良好的营养水平,为后期油分积累奠定物质基础,同时在梅雨季节要注意及时排水。