Journal ArticleDOI
Mechanisms of Dormancy in Rice Seeds : II. New Growth Inhibitors, Momilactone-A and-B Isolated from the Hulls of Rice Seeds
TLDR
In considering the breaking of dormacy in rice seeds, it may be neces-sary to check the interaction between momilactones and GA or IAA which has an important role during rice seed germination.Abstract:
In order to isolate growth and germination inhibitors from the hulls of dormant rice seeds, the seeds of a Japonica cultivar 'Koshihikari' and an Indica one 'Surjamukhi', which have strong dormancy, were used. The rice hull (ca 200kg) was soaked in 80% methanol for about 2 months. The methanol extracts were concentrated to an aqueous phase by the flash evaporator at below 40°C. The aqueous phase was extracted with chloroform and the active fraction was moved in chloroform. The active chloroform fraction was successively fractionated by organic solvents : n-hexane, benzene, ether, ethylene chloride, and ethyl acetate. The biological activity of each extract was checked by lettuce germination test. The active fraction checked was further separated according to solubility in dilute acid or base. The neutral fraction of benzene and ether extracts showed a strong inhibitory activity. The active fraction was used for further chromatographic study. By the silica gel thin layer chromatography with a developing solvent, benzene : ethyl acetate (10 : 1), two active compounds were crystallized and were identified as momilactone-A (C20H2603) and -B (C20H26O4) The momilactones inhibited the seed germination and the seedling growth of rice and lettuce at a concentration of 10-3M. Especially, these substances remarkably inhibited the root growth of rice seedling at 10-5-10-3M. Momilactone-B had stronger inhibition than momilactone-A. The inhibitory activity of momilactone-B was similar to that of a typical growth regulator, abscisic acid. 'Koshihikari' contained more momilactone-A than momilactone-B, while 'Surjamukhi, which has stronger dormancy than 'Koshihikari', held more mornilactone-B than momi-lactone-A. It was supposed that the content of momilactone-A and -B in rice seeds might vary with the rice cultivar. The inhibitory activity of momilactones was partially reduced by GA3 or IAA. In considering the breaking of dormacy in rice seeds, it may be neces-sary to check the interaction between momilactones and GA or IAA which has an important role during rice seed germination.read more
Citations
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Journal ArticleDOI
The role of momilactones in rice allelopathy.
TL;DR: Genetic studies have shown that selective removal of the momilactones only from the complex mixture found in rice root exudates significantly reduces allelopathy, demonstrating that these serve as allelochemicals, the importance of which is reflected in the presence of a dedicatedMomilactone biosynthetic gene cluster in the rice genome.
Journal ArticleDOI
Rice seedlings release momilactone B into the environment.
Hisashi Kato-Noguchi,Takeshi Ino +1 more
TL;DR: The release level of momilactone B and its effectiveness as a growth inhibitor suggest that it may play an important role in rice allelopathy.
Journal ArticleDOI
Confirmation of Potential Herbicidal Agents in Hulls of Rice, Oryza sativa
TL;DR: In biological activity tests using these identified compounds, momilactone A and B showed potent inhibitory activity against duckweed (Lemna paucicostata).
Journal ArticleDOI
Allelopathic substance in rice root exudates: Rediscovery of momilactone B as an allelochemical
TL;DR: A large number of rice varieties were found to inhibit the growth of several plant species when grown together under field and/or laboratory conditions, and it is suggested that rice probably produces and releases allelochemical(s) into the environment.
Journal ArticleDOI
Allelopathy: Potential Role to Achieve New Milestones in Rice Cultivation
M.K. Amb,Amrik Singh Ahluwalia +1 more
TL;DR: A large number of compounds such as phenolic acids, fatty acids, indoles and terpenes have been identified in rice root exudates and decomposing rice residues, as putative allelochemicals which can interact with surrounding environment.
References
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Journal ArticleDOI
Momilactones, Growth inhibitors from rice, Oryza sativa L
Tadahiro Kato,Chizuko Kabuto,Nobuki Sasaki,Mitsuaki Tsunagawa,Hiroyasu Aizawa,Kenichi Fujita,Yoshiaki Kato,Yoshio Kitahara,Norindo Takahashi +8 more
Journal ArticleDOI
Germination Inhibition in Oryza Sativa and Control by Preplanting Soaking Treatments 1
D. S. Mikkelsen,M. N. Sinah +1 more
TL;DR: No effort has been made to determine the nature of the delayed germination in rough (unhulled) rice or to study the relation of preplanting soaking in various chemical solutions to reported faster germination, improved seedling growth, and occasional increased yields of rice.
Journal ArticleDOI
Untersuchungen über den Einfluß von Kaltwasserextrakten aus Getreidestroh und anderer Blattstreu auf Wurzelbildung und-wachstum
A. G. Winter,F. Schönbeck +1 more
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