Isolation of micropropagated strawberry endophytic bacteria and assessment of their potential for plant growth promotion

Twenty endophytic bacteria were isolated from the meristematic tissues of three varieties of strawberry cultivated in vitro, and further identified, by FAME profile, into the genera Bacillus and Sphingopyxis. The strains were also characterized according to indole acetic acid production, phosphate solubilization and potential for plant growth promotion. Results showed that 15 strains produced high levels of IAA and all 20 showed potential for solubilizing inorganic phosphate. Plant growth promotion evaluated under greenhouse conditions revealed the ability of the strains to enhance the root number, length and dry weight and also the leaf number, petiole length and dry weight of the aerial portion. Seven Bacillus spp. strains promoted root development and one strain of Sphingopyxis sp. promoted the development of plant shoots. The plant growth promotion showed to be correlated to IAA production and phosphate solubilization. The data also suggested that bacterial effects could potentially be harnessed to promote plant growth during seedling acclimatization in strawberry.     

三个苹果NBS基因的鉴定及其对外源生长物质的响应

为了探讨苹果NBS基因的生理作用,从苹果中鉴定了NBS家族的3个基因,分别命名为MdNBS、MdTIR-NBS1和MdTIR-NBS-LRR1。这3个基因编码的蛋白质均含有NB-ARC结构域,MdTIR-NBS1和MdTIR-NBS-LRR1蛋白N端还有TIR结构域,MdTIR-NBS-LRR1蛋白在C端含有LRR结构。荧光定量PCR分析表明,这3个不同类型的NBS基因的表达具有明显不同的组织特异性,此外,MdNBS、MdTIR-NBS1和MdTIR-NBS-LRR1在‘嘎啦’苹果幼苗叶片中均受SA和MeJA诱导。ACC处理不能提高MdNBS和MdTIR-NBS1基因的表达,但能诱导MdTIR-NBS-LRR1基因表达。结果表明,MdNBS、MdTIR-NBS1和MdTIR-NBS-LRR1基因可能参与了苹果抗逆或抗病防御反应。     

Resistance to crown rot (Phytophthora cactorum) in strawberry cultivars and in offspring from crosses between cultivars differing in susceptibility to the disease

During a period of five years (1998‐2002), 26 strawberry cultivars and five selections were tested for resistance to crown rot. Cold stored plants inoculated with zoospores of Phytophthora cactorum were used in all experiments. The results showed that resistance to P. cactorum varies greatly between cultivars, and the most resistant ones were Senga Sengana, Induka, Melody, Glima and Bogota, while the most susceptible were Tamella, Inga, Evita and Jonsok. The results were compared to those obtained by other authors, and there were clear indications that the genetic background affects the degree of susceptibility to P. cactorum. Many of the most resistant cultivars descend from Senga Sengana (e.g. Bounty, Glima, Induka and Melody), and several of the most susceptible cultivars have common parentage (e.g. Inga, Tamella, Elsanta and Evita). In a resistance test of the progeny from two separate crosses between a resistant and a susceptible cultivar 61% and 65% of the offspring were intermediately to very susceptible, and 17% and 13% were resistant at the level of Senga Sengana. Hence, there is a high risk of losing offspring with high levels of resistance if selection for resistance to crown rot is not performed at an early stage in a breeding programme.     

草莓FaTT10基因的克隆与表达分析

以‘红颜’草莓为研究材料,本研究采用RT-PCR技术克隆得到FaTT10基因并对其进行生物信息学分析,采用q-PCR技术分析其时空特异性表达模式。结果表明,其开放阅读框为1 704 bp,编码567个氨基酸,蛋白质分子量为62.36 kD,理论等电点为6.69。亚细胞定位预测显示,此基因定位于细胞质膜。同源性及进化树构建结果表明,草莓FaTT10与其他植物漆酶类序列同源性较高。实时荧光定量PCR分析表明,FaTT10在草莓果实不同发育时期及组织器官间均存在表达特异性:在叶、花、匍匐茎、根、茎和果实中都有表达,在小绿果实中表达量最高,在叶中表达量最低;在果实各发育阶段,FaTT10在小绿期表达量最高,随着发育时期推进,表达量逐渐降低。     

Does elevated ozone have differing effects in flowering and deblossomed strawberry?

Fruiting and deblossomed plants of strawberry ( Fragaria × ananassa ) were exposed to 92 ppb ozone or filtered air in open-top chambers for 69 d. Flower and fruit production, relative growth rate of leaf area, leaf gas exchange and plant biomass were investigated. Ozone caused an initial acceleration in inflorescence production, which was followed by a reduction in inflorescence production, fruit set, and, later, individual fruit weight, although total fruit yield was not affected before the end of the fumigation period. Ozone accelerated leaf senescence and had a greater negative effect on the rate of photosynthesis in older than in younger leaves in fruiting and deblossomed plants, but the response of net photosynthesis to ozone did not differ between the two groups of plants. Relative growth rate of leaf area was the first parameter to be reduced by ozone fumigation, with the effect being significant in fruiting, but not in deblossomed, plants. Final above-ground biomass was also significantly decreased by ozone in fruiting plants, but not in deblossomed plants. Root and crown biomass were not significantly affected by ozone fumigation in either fruiting or deblossomed plants.     

The bacterial community associated with adult vine weevil (Otiorhynchus sulcatus) in UK populations growing on strawberry is dominated by Candidatus Nardonella

Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae), commonly known as black vine weevil or simply vine weevil, is an important pest of soft fruit and ornamental crops. This species is endemic to temperate areas of Europe but has spread to many other areas over the last century, including North America and Australasia. The ability of vine weevils to adapt to such different environments is difficult to reconcile with the parthenogenetic reproduction strategy, which is likely to underpin a low genetic diversity. It is therefore tempting to hypothesize that weevil adaptation to different environments is mediated, at least partly, by the microbial communities inhabiting these insects. As a first step towards testing this hypothesis we characterized the composition of the bacterial microbiota in weevils from populations feeding on strawberry plants across four geographically separate locations in the UK. We performed 16S rRNA gene Illumina amplicon sequencing, generating 2 882 853 high‐quality reads. Ecological indices, namely Chao1 and Shannon, revealed that the populations used for this study harboured a low diversity and an uneven bacterial microbiota. Furthermore, β‐diversity analysis failed to identify a clear association between microbiota composition and location. Notably, a single operational taxonomic unit phylogenetically related to Candidatus Nardonella accounted for 81% of the total sequencing reads for all tested insects. Our results indicate that vine weevil bacterial microbiota resembles that of other insects as it has low diversity and it is dominated by few taxa. A prediction of this observation is that location per se may not be a determinant of the microbiota inhabiting weevil populations. Rather, other or additional selective pressures, such as the plant species used as a food source, ultimately shape the weevil bacterial microbiota. Our results will serve as a reference framework to investigate other or additional hypotheses aimed at elucidating vine weevil adaptation to its environment.     

Development and characterization of polymorphic microsatellite markers from Fragaria viridis,a wild diploid strawberry

To date, the development of microsatellite (SSR) markers in the genus Fragaria has focused on F. vesca. However, further species are thought to have contributed to the complex allo‐octoploid genome of the cultivated strawberry, F.×ananassa. Here, we present 22 new SSR markers developed from the diploid species F. viridis. Twenty‐one of the primer pairs amplified polymorphisms in six F. viridis accessions, with an average of 4.95 alleles per primer pair and an average expected heterozygosity of 0.68. Fourteen of these primer pairs, and a locus monomorphic in F. viridis, amplified polymorphic alleles in the parents of a F. vesca mapping population.