Artificial Inoculation In Greenhouse Research Articles

Characterization of Partial Resistance to Bean Rust Disease caused by Uromyces appendiculatus in Seven Common bean Varieties

Partial resistance (PR) to bean rust (Uromyces appendiculatus) in seven bean varieties was determined through three epidemiological parameters, final rust severity (FRS %), area under disease progress curve (AUDPC) and rate of disease increase (r-value) at adult plant stage under natural infection in open field, and four components of resistance (incubation period, latent periods, infection frequency and Pustule size under artificial inoculation in greenhouse) at seedling stage under artificial inoculation in greenhouse. Resistance parameters under both field and greenhouse conditions were varied significantly among bean varieties tested in different years. Montcalm, Nebraska and Bronco were classified partially resistant varieties with decreasing the amount of rust infection and disease development, whereas Karnak, Giza 6, Paulista and Contender were exhibited fast-rusting varieties based on both open field and greenhouse experiments. The partially resistant varieties had higher amounts of three enzymes catalase (CAT), peroxidase (POX) and polyphenoloxidase (PPO) compared with fast-rusting varieties. High significant correlations (r2) were observed among resistance parameters in both field and greenhouse experiments. Correlation matrix suggests that AUDPC and LP50 were good and more reliable parameters for evaluation and selection for resistance to bean rust.

Identification of the blast resistance gene Picl(t) from Chaling common wild rice (Oryza rufipogon Griff.)

AbstractRice blast, caused by the fungal pathogen Magnaporthe oryzae (M. oryzae), is one of the most destructive and widespread plant diseases in the world. Utilization of resistance genes in rice breeding is considered to be an effective and economical method to control this disease. To identify new sources of blast resistance, a set of 1160 introgression lines (ILs) containing chromosome segments of Chaling common wild rice (Oryza rufipogon Griff.) in the genetic background of an elite indica rice variety 93‐11 were developed and phenotyped in the blast nursery. Thirty‐three ILs displaying stable blast resistance in three consecutive years were obtained. Among them, one line, IL1043, was subsequently found to be resistant to all of the 28 M. oryzae isolates from different regions through artificial inoculation in greenhouse. By combining bulk segregant analysis coupled with next‐generation sequencing (BSA‐seq) and recessive class analysis (RCA), a major blast resistance gene in IL1043, designated Picl(t), was mapped on rice chromosome 6 flanked by the markers RM527 and Indel6 with an interval of approximately 925 kb, which covers the Pi2/9 locus. These results will facilitate fine mapping and cloning of Picl(t), and the linked markers will further provide a useful tool for rice blast resistance breeding.

QTL analysis reveals new eggplant loci involved in resistance to fungal wilts

Fusarium spp. and Verticillium spp. are widespread soil pathogens responsible for vascular wilts causing heavy yield losses in eggplant (Solanum melongena) as well as in many other crops. Here we report on the identification of QTLs affecting the resistance to Fusarium and Verticillium in an F2 intraspecific population of 156 individuals bred from the cross ‘305E40’ × ‘67/3’, we previously characterized for key agronomic and biochemical traits. The female parent (‘305E40’) is an androgenetic introgressed line carrying the resistance locus Rfo-Sa1 derived from Solanum aethiopicum. The line is fully resistant to Fusarium and also displays a previously uncharacterized partial resistance to Verticillium. The male parent (‘67/3’) is an F8 selection from the eggplant intra-specific cross cv. ‘Purpura’ x cv. ‘CIN2’ which, unexpectedly, revealed a not previously characterized partial resistance to Fusarium, but it is highly susceptible to Verticillium. The degree of resistance of the F2 population was assessed following artificial inoculation in greenhouse (Fusarium) or growth chamber (Verticillium) of F2:3 progenies obtained by selfing each F2 individual. Other than a major QTL for the resistance to Fusarium, which lies in the genomic region of the Rfo-Sa1 locus, major and minor QTL influencing the response to both Fusarium and Verticillium were spotted, and putative tomato orthologous genes were identified as well. The markers linked to the spotted QTL may find application in the context of marker-assisted breeding.

Production and evaluation of transgenic sweet orange ( Citrus sinensis Osbeck) containing bivalent antibacterial peptide genes ( Shiva A and Cecropin B) via a novel Agrobacterium-mediated transformation of mature axillary buds

Transgenic plants of Jincheng orange ( Citrus sinensis Osbeck) and Newhall navel orange ( C. sinensis Osbeck) containing antibacterial peptide genes Shiva A and Cecropin B were successfully obtained by a novel Agrobacterium tumefaciens-mediated transformation of the mature axillary buds. PCR and Southern blot analysis of the transgenic plants verified that the Shiva A and Cecropin B genes were integrated into the citrus genome. The transgenic plants began to blossom and bear fruit in the 2nd year after grafting on trifoliate orange ( Poncirus trifoliata Raf) rootstock in greenhouse. Water-soluble extracts from transgenic citrus leaves exhibit in vitro suppressive effects on Xanthomonas axonopodis pv. citri, suggesting that the expressed products of Shiva A and Cecropin B in citrus retain their native antibacterial activities. Artificial inoculation in greenhouse and open field further indicates significantly increased resistance of transgenic plants to X. axonopodis pv. citri when compared with non-transgenic lines. No significant difference was found in the content of total soluble solids, total acidity, reduced sugar content and other fruit characteristics between transgenic and non-transgenic plants. In this present study, 11 transgenic lines were obtained from 40 transgenic lines, showing enhanced resistance to citrus canker disease.

Molecular mapping of a non-host resistance gene YrpstY1 in barley (Hordeum vulgare L.) for resistance to wheat stripe rust

Cultivated barley (Hordeum vulgare L.) is considered as a non-host or inappropriate host species for wheat stripe rust caused by Puccinia striiformis f. sp. tritici. Most barley cultivars show a broad-spectrum resistance to wheat stripe rust. To determine the genes for resistance to wheat stripe rust in barley, a cross was made between a resistant barley line Y12 and a susceptible line Y16. The two parents, F(1) and 147 BC(1) plants were tested at seedling stage with Chinese prevalent race CYR32 of Puccinia striiformis f. sp. tritici by artificial inoculation in greenhouse. The results indicated that Y12 possessed one dominant resistance gene to wheat stripe rust, designated YrpstY1 provisionally. A total of 388 simple sequence repeat (SSR) markers were used to map the resistance gene in Y12 using bulked segregant analysis. A linkage map, including nine SSR loci on chromosome 7H and YrpstY1, was constructed using the BC(1) population, indicating that the resistance gene YrpstY1 is located on chromosome 7H. It is potential to transfer the resistance gene into common wheat for stripe rust resistance.

혹명나방 저항성벼(Cry1Ac1)의 병해 저항성 및 병원균으로의 유전자 전이

유전자 변형 혹명나방 저항성벼의 주요 병해에 대한 저항성 변화를 온실과 포장에서 모본으로 사용된 낙동벼와 비교하였다. 포장에서 벼잎집무늬마름병과 벼깨씨무늬병의 발병 정도는 큰 차이가 없었다. 온실에서 인위적으로 병원균을 접종하여 벼도열병과 흰잎마름병에 대해 저항성 변화여부를 조사한 결과에서도 두 품종간에 큰 차이를 보이지 않았고, 인위접종한 벼잎집무늬마름병에 대한 감수성도 두 품종간에 비슷하여 포장에서의 결과와 같은 경향을 보였다. 형질전환 벼의 제초제 저항성 유전자(Bar 유전자)와 혹병나방 저항성유전자(Cry1Ac1 유전자)가 병원균으로 전이되는가의 여부를 조사하기 위하여 포장에서 발병한 도열병과 키다리병원균을 분리한 후 DNA를 추출하여 PCR을 실시한 결과 두 유전자 모두 병원균으로 전이되지 않은 것으로 확인되었다. 또한, 병원균과 저항성벼의 지속적인 접촉에 의한 유전자 전이 가능성을 확인하기 위하여 잎집무늬마름병균과 흰잎마름병균을 계대 접종한 후 DNA를 분리하여 조사한 결과에서도 저항성 유전자의 전이는 일어나지 않은 것으로 확인되어, 본 실험에서는 자연상태와 인위적인 조건 모두에서 유전자 전이를 찾아 볼 수 없었다. The genetically modified leaffolder-resistant (Cry1Ac1) rice plant was evaluated for the changes of resistance by comparing the occurrence of major diseases with a japonica type Korean rice variety, Nakdong which was the mother plant of the transgenic rice event, in greenhouse and field conditions. There was no difference in the occurrence of sheath blight and Helminthosporium blight between the two varieties in the fields. We couldn't find any difference of resistance for fungal blast and bacterial leaf blight by artificial inoculation in greenhouse. There was also no difference in the susceptibility to sheath blight in artificial inoculation tests confirming the results in the fields. The possibility of gene transfer of Bar and Cry1Ac1 from the genetically modified rice plant to naturally infected pathogens such as Fusarium moniliforme and Pyricularia oryzae in the field conditions was tested by PCR. And the possible transfer of those genes by continuous inoculation of Xanthomonas oryzae pv. oryzae and Rhizoctonia solani was also tested. However, we couldn't find any possibility of transfer of the genes in natural and artificial conditions.

POTENTIAL RAPD APRICOT MARKER LINKED TO PPV RESISTANCE

Sharka (plum pox virus or PPV) is the most economically important virus disease of fruit crops in Europe. The sharka virus became the most limiting factor for apricot crops and a severe problem for other Prunus species. The evaluated progeny in this study was a controlled intraspecific cross between: 'Vestar' (female parent), a Slovak cultivar susceptible to PPV and 'Stark Early Orange' (male parent), an American self-compatible cultivar resistant to PPV. The evaluated population consisted of 32 individuals. The basic screening of 155 primers was used to find the group of primers able to distinguish susceptible, resistant and immune cultivar. Twenty primers were chosen giving repeatable strong and middle strong bands. They were subsequently used for the RAPD reactions within the individuals. Among twenty primers, only twelve segregated in evaluated progeny. This segregation was compared with results obtained from evaluation of sharka resistance after artificial inoculation in greenhouse. Among selected primers, one potential marker OPX6-330 was found. Out of thirty-two progenies obtained from an evaluated crossing, sixteen scored resistant and sixteen scored susceptible. Identity of classified resistance and values obtained from RAPD analysis was 78.1 percent. The probability (p) values for the ratios (1:1) in this populations are greater than 0.05. These results indicated an approximate segregation ratio of 1:1 for susceptible and resistant, suggesting a single dominant gene, which probably may be involved in controlling the resistance to PPV-D strain. In the future, this population will be screened again, and other population will be also tested.

Panicle Blast Resistance of Rice Varieties Evaluated by Natural Infection in Fields and Artificial Inoculation in Greenhouse

Panicle Blast Resistance of Rice Varieties Evaluated by Natural Infection in Fields and Artificial Inoculation in Greenhouse