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Kato-Noguchi H.,Kagawa University | Le Thi H.,Kagawa University | Le Thi H.,Cuulong Delta Rice Research Institute | Teruya T.,Keio University | Suenaga K.,Keio University
Scientia Horticulturae | Year: 2011

Since cucumber plants are mostly discarded as large waste after crop harvesting, allelopathy of cucumber plants was investigated for possible weed management options and utilization of the waste. Two potent growth inhibitory substances were isolated from an aqueous methanol extract of cucumber (Cucumis sativus L. cv. Phung Tuong) plants. These substances were determined as 9-hydroxy-4,7-megastigmadien-9-one (HMO) and (6S,7E,9S)-6,9,10-trihydroxy-4,7-megastigmadien-3-one (THMO) by the analysis of MS, 1H NMR spectra and optical rotation. HMO inhibited the growth of cress (Lepidium sativum L.) and Echinochloa crus-galli (L.) Beauv seedlings at concentrations greater than 0.3 and 1μM, respectively. THMO inhibited the growth of cress and E. crus-galli seedlings at concentrations greater than 1 and 3μM, respectively. The concentrations required for 50% growth inhibition on roots and shoots of cress and E. crus-galli were 2.4-29.3μM for HMO and 8.1-52.2μM for THMO. The endogenous levels of HMO and THMO in cucumber plants were 31.8 and 43.5μgg-1 dry weight, respectively. These results suggest that HMO and THMO may be the causal factors for the growth inhibitory effect of cucumber plants. Therefore, cucumber plants may be potentially useful for weed management options in an agricultural setting, such as a cover crop and soil admixture, which should be investigated further in the field. © 2011 Elsevier B.V. Source


Kato-Noguchi H.,Kagawa University | Le Thi H.,Kagawa University | Le Thi H.,Cuulong Delta Rice Research Institute | Sasaki H.,Keio University | Suenaga K.,Keio University
Acta Physiologiae Plantarum | Year: 2012

A potent growth inhibitory substance was isolated from an aqueous methanol extract of cucumber (Cucumis sativus L. cv. Phung Tuong) plants and determined as (2S)-2,3-dihydro-2α-(4-hydroxy-3-methoxyphenyl)-7-methoxy-5-(1,2,3-trihydroxypropyl)benzofuran-3β-methanol (sisymbrifolin) by spectral data. Sisymbrifolin inhibited the growth of cress (Lepidium sativum) and Echinochloa crus-galli seedlings at concentrations greater than 3 μM. Concentration of sisymbrifolin in the cucumber plants was the greatest among four growth inhibitory substances, (S)-2-benzoyloxy-3-phenyl-1-propanol, 9-hydroxy-4,7-megastigmadien-9-one, (6S,7E,9S)-6,9,10-trihydroxy-4,7-megastigmadien-3-one, and sisymbrifolin found in the cucumber, whereas growth inhibitory activity of 9-hydroxy-4,7-megastigmadien-9-one against cress and E. crus-galli was the greatest. Total activities of these substances (concentration of the substance/concentration required 50 % growth inhibition) were 14. 4, 13. 2, 8. 5 and 10. 7 for (S)-2-benzoyloxy-3-phenyl-1-propanol, 9-hydroxy-4,7-megastigmadien-9-one, (6S,7E,9S)-6,9,10-trihydroxy-4,7-megastigmadien-3-one and sisymbrifolin, respectively. These total activities were about 100-fold greater than those of phenolic acids, which are often mentioned as putative allelochemicals of plants. Thus, these substances may play important roles in the allelopathy of cucumber plants through the growth inhibition of neighboring plant species. © 2012 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków. Source


Vu Q.,International Rice Research Institute | Vu Q.,Cuulong Delta Rice Research Institute | Quintana R.,International Rice Research Institute | Fujita D.,International Rice Research Institute | And 4 more authors.
Entomologia Experimentalis et Applicata | Year: 2014

The green leafhopper, Nephotettix virescens (Distant) (Hemiptera: Cicadellidae), occasionally damages rice in Asia either directly, by feeding on the host phloem, or indirectly by transmitting tungro virus. We assessed the nature of resistance against the leafhopper in monogenic and pyramided near-isogenic rice lines containing the resistance genes Grh2 and Grh4. Only the pyramided line was resistant to leafhopper damage. Leafhopper nymphs and adults had high mortality and low weight gain when feeding on the pyramided line and adults laid few eggs. In contrast, although there was some minor resistance in 45-day-old plants that possessed either Grh2 or Grh4 genes, the monogenic lines were generally as susceptible to the leafhopper as the recurrent parent line Taichung65 (T65). Resistance in the pyramided line was stable as the plant aged and under high nitrogen, and affected each of five Philippine leafhopper populations equally. Furthermore, in a selection study, leafhoppers failed to adapt fully to the pyramided resistant line: nymph and adult survival did improve during the first five generations of selection and attained similar levels as on T65, but egg-laying failed to improve over 10 generations. Our preliminary results suggested that resistance was associated with physiological costs to the plants in some experiments. The results of this study demonstrate the success of pyramiding resistance genes through marker-assisted breeding, to achieve a strong and potentially durable resistance. We discuss the utility of gene pyramiding and the development of near-isogenic lines for leafhopper management. © 2013 The Netherlands Entomological Society. Source


Calingacion M.,International Rice Research Institute | Calingacion M.,Wageningen University | Calingacion M.,A+ Network | Laborte A.,International Rice Research Institute | And 92 more authors.
PLoS ONE | Year: 2014

With the ever-increasing global demand for high quality rice in both local production regions and with Western consumers, we have a strong desire to understand better the importance of the different traits that make up the quality of the rice grain and obtain a full picture of rice quality demographics. Rice is by no means a 'one size fits all' crop. Regional preferences are not only striking, they drive the market and hence are of major economic importance in any rice breeding / improvement strategy. In this analysis, we have engaged local experts across the world to perform a full assessment of all the major rice quality trait characteristics and importantly, to determine how these are combined in the most preferred varieties for each of their regions. Physical as well as biochemical characteristics have been monitored and this has resulted in the identification of no less than 18 quality trait combinations. This complexity immediately reveals the extent of the specificity of consumer preference. Nevertheless, further assessment of these combinations at the variety level reveals that several groups still comprise varieties which consumers can readily identify as being different. This emphasises the shortcomings in the current tools we have available to assess rice quality and raises the issue of how we might correct for this in the future. Only with additional tools and research will we be able to define directed strategies for rice breeding which are able to combine important agronomic features with the demands of local consumers for specific quality attributes and hence, design new, improved crop varieties which will be awarded success in the global market. Source


Lang N.T.,Cuulong Delta Rice Research Institute | Nha C.T.,Cuulong Delta Rice Research Institute | Ha P.T.T.,Cuulong Delta Rice Research Institute | Buu B.C.,Vietnam Institute of Agricultural Sciences
Sabrao Journal of Breeding and Genetics | Year: 2013

SSR genotyping was combined with selective genotyping to map quantitative trait loci (QTLs) associated with drought tolerance in rice. A total of 229lines (BC2F2) derived from the cross of OM1490/WAB880-1-38-18-20-P1- HB was evaluated for drought at flowering (DRF), root dry weight (RDW), and root length (RL). A microsatellite map of this population was constructed with 232 markers to detect the linkage to the target traits. The map covered 2,553.7 cM with an average interval of 10.97 cM between marker loci. Markers associated with drought tolerance were located on chromosomes 2, 3, 4, 8, 9, 10 and 12. QTL mapping was used to determine effects of loci associated with drought tolerance traits. We also mapped QTLs for morphological attributes related to drought tolerance. Chisquare tests (χ2), single maker analysis (SMA), interval mapping (IM) were combined in the QTL analysis. All approaches used for QTL detection obtained similar results. QTLs were identified for drought tolerance with the emphasis on 2 QTLs for RL, and 2 QTLs for RDW. The proportion of phenotypic variation explained by each QTL ranged from 20.7% to 30.8% for dry root weight (DRW) and from 6.2 to 3.4% for morphological characters related to drought at flowering. This study has provides detailed information on the potential of using marker-assisted selection for drought tolerance. © Society for the Advancement of Breeding Research in Asia and Oceania (SABRAO) 2013. Source

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