Cloning and sequencing of cDNAs encoding two SSS

Ai, Yunjun; Tsai, De Sheng; Kao, Teh Hui

doi:10.1007/bf00023404

Cited by 23 publications

(2 citation statements)

References 22 publications

(28 reference statements)

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“…Petunia hybrida possesses both functional and relic S-RNases proteins (Ai et al , 1992; Lee et al , 1992; Robbins et al , 2000). However, it has been shown that relic S-RNases are always more closely related to the S-RNases from the same family than to other RNases (Golz et al , 1998; Liang et al , 2003).…”

Section: Discussionmentioning

confidence: 99%

Petunia nectar proteins have ribonuclease activity

Hillwig

Liu

et al. 2010

Journal of Experimental Botany

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Plants requiring an insect pollinator often produce nectar as a reward for the pollinator's visitations. This rich secretion needs mechanisms to inhibit microbial growth. In Nicotiana spp. nectar, anti-microbial activity is due to the production of hydrogen peroxide. In a close relative, Petunia hybrida, limited production of hydrogen peroxide was found; yet petunia nectar still has anti-bacterial properties, suggesting that a different mechanism may exist for this inhibition. The nectar proteins of petunia plants were compared with those of ornamental tobacco and significant differences were found in protein profiles and function between these two closely related species. Among those proteins, RNase activities unique to petunia nectar were identified. The genes corresponding to four RNase T2 proteins from Petunia hybrida that show unique expression patterns in different plant tissues were cloned. Two of these enzymes, RNase Phy3 and RNase Phy4 are unique among the T2 family and contain characteristics similar to both S- and S-like RNases. Analysis of amino acid patterns suggest that these proteins are an intermediate between S- and S-like RNases, and support the hypothesis that S-RNases evolved from defence RNases expressed in floral parts. This is the first report of RNase activities in nectar.

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Section: Discussionmentioning

confidence: 99%

Petunia nectar proteins have ribonuclease activity

Hillwig

Liu

et al. 2010

Journal of Experimental Botany

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“…In terms of the evolutional change of plant RNases, knowledge is limited to those plants belonging to Dicotyledoneae, except for barley. 10) These include several plants of Solanaceae [tomato, 4,11) and tobacco, 3,12) petunia 13) and a kind of potato 14) ], Cucurbitaceae [bitter gourd, 7) cucumber, 8) melon 9) ], Rosacease [pear 15) ], Arabidopsis, 16) Zinnia elegance, 17) Panax ginnseng 18) and others. In this report, we will describe the amino acid sequence of an RNase from rice bran (Oryza sativa) which is a member of Monocotyledoneae, and its enzymatic properties.…”

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confidence: 99%

Amino Acid Sequence and Characterization of a Rice Bran Ribonuclease

Iwama

Ogawa

Yamagishi

et al. 2001

Biological & Pharmaceutical Bulletin

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RNase T2 family enzymes which are base non-specific and have a molecular mass of about 24 kDa, distributed widely from viruses to microbes, plants and animals. 1)They share two well conserved active site sequences, CAS I and CAS II. Therefore, they are a good model with which to study the evolution of RNases. In the plant kingdom, members of the RNase T2 family are classified into two classes, S-RNases which are the products of S-genes and function as self-incompatibility factors, 2) and S-like RNases.3) The latter enzymes are known to be induced by phosphate deprivation [Jost et al.,4) Bariola et al. 5)], in the case of senescence [Lers et al. 6) ], and exist in the seeds probably for defense [Ide et al.,7) Rojo et al. 8,9) ]. In terms of the evolutional change of plant RNases, knowledge is limited to those plants belonging to Dicotyledoneae, except for barley. 10) These include several plants of Solanaceae [tomato,4,11) and tobacco, 3,12) petunia 13) and a kind of potato 14) ], Cucurbitaceae [bitter gourd, 7) cucumber, 18) and others. In this report, we will describe the amino acid sequence of an RNase from rice bran (Oryza sativa) which is a member of Monocotyledoneae, and its enzymatic properties. MATERIALS AND METHODSEnzymes Lysylendopeptidase and g-pyroglutamine aminopeptidase were obtained from Wako Pure Chemical Ind., Ltd. (Osaka, Japan) and Calbiochem-Novabiochem. Co., Ltd., (LaJolla, LA, U.S.A.), respectively.Other Reagents Yeast RNA was a product of Marin Bio (Tokyo, Japan). Sixteen dinucleoside phosphates were purchased from Sigma (St. Louis, MO, U.S.A.). Phospho-cellulose and DE-52 were obtained from Whatman (Clifton, NJ, U.S.A.). A Mono Q column was obtained from Amersham Pharmcia Biotech (Buckinghamshire, England).Enzyme Assay (i) RNA as substrate: RNase assay was carried out as described 19) with RNA as substrate at pH 5.5 and 37°C. (ii) Dinucleosidephosphates as substrate: The rates of hydrolysis of 16 dinucleoside phosphates (XpYs), where X and Y were one of A, G, C and U, were measured spectrophotometrically as described by Imazawa et al. 20) in 0.1 M sodium acetate buffer (pH 5.5) at 22°C.Protein Concentration The protein concentration was measured spectrophotometrically assuming the absorbancy at 280 nm of a 0.1% protein solution to be 1.0.Purification of an RNase from Rice Bran Purification of an RNase from rice bran was performed by modification of the procedure reported by Yokoyama et al. 21)Step 1. Four kilograms of rice bran (product from a strain of Oryza sativa, Koshihikari) was suspended in 12 l of 20 mM sodium phosphate buffer (pH 7.0) and extracted by vigorous stirring at 4°C. The extract was filtered through a layer of cotton sheet, and the filtrate was centrifuged at 10000 rpm for 10 min. The pH of the supernatant was adjusted to 5.0 by addition of dil. HCl. The supernatant was kept at 4°C overnight, and the precipitate formed was eliminated by centrifugation at 10000 rpm for 10 min (crude extract).Step 2. The crude extract was fractionated by ammonium sulfate, and the pr...

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Wie können Pflanzen eine Selbstbefruchtung vermeiden?

Naß

1999

Biologie in unserer Zeit

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Trotz der engen Nachbarschaft weiblicher und mannlicher Geschlechtszellen in ihren Bluten vermeiden viele Pflanzen aus unterschiedlichen Familien die Selbstbefruchtung mit Hilfe ausgeklugelter Mechanismen. Von zentraler Bedeutung ist hierbei die Erkennung und AbstoiSung des eigenen Pollens. cheinbar hat es Vorteile, Zwitter zu S sein. Die Erstbesiedlung neuer oder gestorter Lebensraume wird durch die Moglichkeit zur Selbstbefruchtung vereinfacht oder bei Abwesenheit von Sexualpartnern sogar erst moglich. Aus einem einzigen Samen einer selbstbestaubenden Pflanze kann sich, bei gleichzeitig hoher Reproduktionsrate, schnell eine groi3e Population aufbauen. Viele kleine Brassicaceen (Kreuzbliitler), wie etwa die Ackerschmalwand Arabidopsis thaliana, sind dafur gute Beispiele. Doch uneingeschrankte Selbstbefruchtung hat offensichtliche Nachteile. Ungiinstige Mutationen haufen sich im Genom an, und die durch Durchmischung des Erbgutes bewirkten Heterosiseffekte entfalten sich nicht. Daher finden sich in etwa der Halfte aller Pflanzenfamilien Arten, bei denen Selbstbefruchtung (Autogamie) ausgeschlossen ist [5]. Verbreitete Mechanismen, die eine Allogamie (Fremdbefruchtung) begiinstigen, sind unterschiedliche Reifezeitpunkte und -orte der weiblichen und mannlichen Gameten auf einer Pflanze oder die Diozie (Zweihausigkeit), bei der weibliche und mannliche Gameten auf unterschiedlichen Individuen gebildet werden. Weiterhin gibt es eine Vielzahl morphologischer Barrieren, die das zufallige Bestauben mit dem eigenen Pollen behindern und Pflanzen haufig an Tiere als Pollenubertrager von Bliite zu Bliite binden. ,,Echte" selbstinkompatible Pflanzen konnen den eigenen Pollen oder den der ,,naheren Verwandtschaft" erkennen und an der Befruchtung hindern, sie sind aber nicht etwa steril, wie der friiher gebrauchliche Begriff Selbststerilitat nahelegte, da sie fertile Gameten bilden. Erkannt wurde das Phanom e n x h o n 1764 von Kolreuter fur die Konigskerze Verbascum phoenicicum, doch die erste eingehende Analyse und Zusammenfassung dieser Daten und eigener Befunde erfolgte spater (1867) durch Charles Darwin. Er erkannte als erster, dai3 die beobachtete Unfruchtbarkeit durchaus als ,,Begabung" angesehen werden kann. Viele landwirtschaftlich genutzte Arten sind heute selbstkompatibel, weil im Laufe ihrer Kulturgeschichte die Selbstinkompatibilitats-Mechanismen verlorengegangen sind oder bewui3t darauf verzichtet wurde. Dies hat gute Griinde: Einer davon ist vor allem eine Ertragssteigerung durch die ungehinderte (Selbst-)Befruchtung. Allerdings ist mit solchen Pflanzen die Produktion von Hybridsaatgut zur ,,Handarbeit" des Ziichters geworden. Im Zeitalter teurer menschlicher Arbeitskraft hat daher jede Art von Pollensterilitat nicht zu unterschatzende wirtschaftliche Bedeutung gewomen. Die (Ruck-)Ubertragung eines funktionierenden Selbstinkompatibilitatssystems auf Kulturpflanzen erscheint hier als ein Losungsweg, insbesondere da solche Pflanzen weiterhin fertilen Pollen produzieren konnten, also nicht steril waren. Allerdings is...

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Cloning and sequencing of cDNAs encoding two SSS

Cited by 23 publications

References 22 publications

Petunia nectar proteins have ribonuclease activity

Petunia nectar proteins have ribonuclease activity

Amino Acid Sequence and Characterization of a Rice Bran Ribonuclease

Wie können Pflanzen eine Selbstbefruchtung vermeiden?

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