Elżbieta Węgrzynowicz-Lesiak

MORPHACTIN SUBSTANTIALLY INDUCED THE FOURTH INTERNODE GROWTH IN DECAPITATED TULIPS: RELEVANCE TO ENDOGENOUS LEVELS OF INDOLE-3-ACETIC ACID

Abstract Important role of auxin polar transport inhibitors such as TIBA (2,3,5- triiodobenzoic acid), NPA (N-(1-naphthyl)phthalamic acid) and morphactin (methyl 2-chloro-9-hydroxyfluorene-9-carboxylate) in stem growth of tulips was intensively studied. After the application of morphactin above the 3rd node of decapitated tulips, the stimulated growth of the 4th internode was clearly observed. On the other hand, NPA and TIBA were slightly effective in stimulating the 4th internode growth of tulips. Endogenous levels of IAA in the 4th internode after the treatment of auxin polar transport inhibitors were determined using gas-liquid chromatography-mass spectrometry (GC-MS) and gas-liquid chromatography-mass spectrometry selected ion monitoring system (GC-SIM) with deuterium labelled IAA (Indole-2,4,5,6,7-d5-3- acetic acid, d5-IAA) as an internal standard, resulted in significant accumulation of IAA in the 4th internode of tulips after the treatment of morphactin. In the treatment of NPA and TIBA, there was almost no such an accumulation of IAA. These results strongly suggest that stimulated growth of the 4th internode of tulips induced by the application of morphactin is the consequence of accumulated endogenous levels of IAA after the treatment. The possible mode of action of auxin polar transport inhibitors in tulip stem growth is also discussed. Streszczenie Rola inhibitorów polarnego transportu auksyny, takich jak kwas 2,3,5- trójjodobenzoesowy (TIBA), kwas naftyloftalamowy (NPA) i morfaktyna (kwas metylo 2-chloro-9-karboksylowy) była intensywnie badana na wzrost łodygi tulipana. Traktowanie morfaktyną łodygi tulipana powyżej 3. węzła, po odcięciu pąka kwiatowego, powodowało stymulację wzrostu 4. międzywęźla. Z drugiej strony, inhibitory polarnego transportu, NPA i TIBA, przy takim samym traktowaniu, wywierały mały wpływ na wzrost 4. międzywęźla. Endogenny poziom IAA w 4. międzywęźlu, po traktowaniu inhibitorami polarnego transportu, morfaktyną, NPA i TIBA, określano stosując metodę GC-MS i GC-SIM ze znakowanym IAA (kwas indolo-2,4,5,6,7-d5-3- octowy) jako standard wewnętrzny. Stwierdzono silną akumulację IAA w 4. międzywęźlu łodygi po traktowaniu morfaktyną. Traktowanie NPA i TIBA powodowało tylko niewielką akumulację IAA w 4. międzywęźlu. Otrzymane wyniki wskazują, że stymulacja wzrostu 4. międzywęźla pod wpływem morfaktyny jest konsekwencją akumulacji IAA w tym międzywęźlu. Możliwy sposób działania inhibitorów polarnego transportu auksyny we wzroście łodygi tulipana jest w pracy dyskutowany

THE EFFECT OF SOME PLANT GROWTH REGULATORS AND THEIR COMBINATION WITH METHYL JASMONATE ON ANTHOCYANIN FORMATION IN ROOTS OF KALANCHOE BLOSSFELDIANA

Abstract In this study, we investigated the effect of plant growth regulators (PGRs) - auxins, gibberellin, cytokinin, abscisic acid, brassinosteroid, ethylene and their interaction with methyl jasmonate (JA-Me) applied to roots of the whole plants Kalanchoe blossfeldiana on the accumulation of anthocyanins in roots. The highest stimulation of anthocyanins synthesis was stated with application of JA-Me alone. In response to treatments with the other tested PGRs, the content of anthocyanins in roots of a whole plant was different depending on the concentration of the PGR when being applied alone or together with JA-Me. Auxin, indole-3-acetic acid (IAA) at a concentration of 50 mg·L-1, indole-3-butyric acid (IBA) at 5 mg·L-1 and abscisic acid (ABA) at 10 mg·L-1 induced anthocyanin accumulation with approximately 60-115% compared to the control while 24-epibrassinolid (epiBL), gibberellic acid (GA3) and 6-benzylaminopurine (BAP) had no effect on the anthocyanin accumulation. The simultaneous administration of the PGRs with JA-Me usually resulted in the accumulation of anthocyanins in roots in a manner similar to that caused by JA-Me. PGRs applied to isolated roots did not stimulate anthocyanin accumulation, except for the combination of JA-Me with 50 mg·L-1 IAA. The results indicate that in K. blossfeldiana, the aboveground parts of the plant play an important role in the biosynthesis of anthocyanins in roots.

Effects of sugars on the growth and chlorophyll content in excised tulip stem in the presence of indole-3-acetic acid.

ABSTRACT The purpose of this study was to clarify the effect of sucrose on auxin-induced growth of stem excised from growing tulips and excised directly from cooled and not cooled bulbs, and on the growth of excised IV internode from growing plants in the presence of auxin. In all cases flower bud was replaced by IAA (indole-3- acetic acid, 0.1%, w/w in lanolin) and basal part of excised segments of stem was kept in distilled water or in solution of various sugars at different concentrations. IAA-induced growth of excised stems isolated from growing tulips was inhibited by sucrose at concentrations of 5.0% and 10.0%, but sucrose at 1.25% and 2.5% did not. Sucrose at all concentrations used evidently delayed senescence and increased chlorophyll contents in excised stems in the presence of IAA. Sucrose induced stiffing in isolated stems in the presence of IAA, and much less infective by pathogen in comparison to stem treated with IAA only. Mannitol and sorbitol at concentrations of 5.0% and 10.0% substantially inhibited IAA-induced growth of stem segments. Stem segments excised from cooled and not cooled tulip bulbs were more sensitive than those isolated from growing shoots due to application of sucrose and glucose; more inhibitory effect was observed. Sucrose at concentrations of 5.0% and 10.0% only slightly inhibited growth of IV internode treated with IAA and all concentrations of sucrose (1.25%, 2.5%, 5.0% and 10.0%) substantially increased chlorophyll content. The possible mode of actions of sucrose interacting with auxin to regulate stem growth is also discussed although sugar response is complicated by the fact that plants have multiple sugar-response pathways. STRESZCZENIE Celem badań było poznanie wpływu sacharozy i glukozy na indukowany przez auksynę (IAA) wzrost izolowanych łodyg z rosnących tulipanów i izolowanych bezpośrednio z przechłodzonych i nieprzechłodzonych cebul tulipana, oraz na wzrost izolowanego IV międzywęźla z rosnących roślin w obecności auksyny. We wszystkich traktowaniach usunięty pąk kwiatowy był zastąpiony przez IAA (0,1%, w paście lanolinowej), dolna część izolowanych segmentów była trzymana w wodzie destylowanej lub w roztworze cukrów o różnym stężeniu. Indukowany przez IAA wzrost izolowanych łodyg z rosnących tulipanów był hamowany przez sacharozę w stężeniu 5% i 10%, a sacharoza w stężeniu 1,25% i 2,5% nie powodowała zmian we wzroście. Sacharoza we wszystkich zastosowanych stężeniach opóźniała starzenie się łodyg i powodowała wzrost zawartości chlorofilu w izolowanych łodygach w obecności IAA. Sacharoza indukowała większą sztywność izolowanych łodyg w obecności IAA, a łodygi były dużo bardziej odporne na infekcje przez grzyby w porównaniu z izolowanymi łodygami traktowanymi tylko IAA. Mannitol i sorbitol w stężeniach 5% i 10% hamowały wzrost izolowanych łodyg indukowany przez auksynę. Łodygi tulipana izolowane bezpośrednio z przechłodzonych i nieprzechłodzonych cebul były bardziej wrażliwe na traktowanie sacharozą i glukozą w obecności auksyny niż łodygi izolowane z rosnących tulipanów; stwierdzono większe hamujące działanie cukrów. Sacharoza w stężeniach 5% i 10% w małym stopniu hamowała wzrost IV międzywęźla traktowanego IAA, ale wszystkie zastosowane stężenia sacharozy (1,25%; 2,5%; 5% i 10%) powodowały wzrost zawartości chlorofilu. W pracy dyskutowane jest możliwe działanie sacharozy w interakcji z auksyną w regulacji wzrostu izolowanych łodyg, chociaż mechanizm ten jest złożony ze względu na wielokierunkowe oddziaływanie cukrów na metabolizm rośliny.

Effects of methyl jasmonate and gums formed in stone fruit trees on in vitro ethylene production by mycelium of verticillium dahliae and alternaria alternata

ABSTRACT The knowledge about the role of jasmonates in ethylene production by pathogenic fungi is ambiguous. In this study, we describe the effect of methyl jasmonate (JA-Me) and gums formed in stone fruit trees on the growth and in vitro ethylene production by mycelium of Verticillium dahliae and Alternaria alternata. Methyl jasmonate at concentrations of 100, 250 and 500 μg·cm-3 inhibited the mycelium growth of V. dahliae and A. alternata, proportionally to the concentrations used. After 8 days of incubation, JA-Me at concentration of 500 μg·cm-3 limited the area of mycelium of these pathogens by 7-8 times but did not entirely inhibited the pathogen growth. Addition of gums produced by trees of cherry and peach to a medium containing 40 μg·cm-3 JA-Me did not influence the mycelium growth of V. dahliae, but gums of plum and apricot trees stimulated mycelium growth, in comparison to JA-Me only. Methyl jasmonate at concentrations of 2 and 40 μg·cm-3 stimulated the ethylene production by mycelium of V. dahliae and A. alternata. It is possible that methyl jasmonate stimulated ethylene production in mycelium of these pathogens through interaction with some fractions of galactans formed during hydrolysis of agar. The lack of interaction of JA-Me with polysaccharides of stone fruit trees gums concerning ethylene production was documented and it needs further explanation.

Effects of auxin polar transport inhibitors on the growth of the excised fourth internode in tulips

ABSTRACT Effects of auxin polar transport inhibitors: methyl 2-chloro-9-hydroxyfluorene-9-carboxylate (morphactin IT 3456), 2,3,5-triiodobenzoic acid (TIBA) and N-1-naphthylphthalamic acid (NPA) on elongation growth of the excised fourth internode of tulips (Tulipa gesneriana L.) cv. Apeldoorn were studied. After removal of flower bud, the continuing elongation of the excised fourth internode kept in water in normal or inverted position was observed, the elongation in inverted position being significantly higher than that in the normal position. On the other hand, the application of these inhibitors (0.2%, w/w in lanolin) in the place of removed flower bud substantially enhanced the elongation, the stimulation being much higher in the normal position than in the inverted one. When the inhibitors were applied in the middle or 1 cm from the base of the internode, the growth-promoting effect of these inhibitors was observed both in the upper and lower part of the internode, being greater in the upper part of the internode, regardless of the position of explants. Simultaneous application of indole-3-acetic acid (IAA) (0.1%, w/w in lanolin) at the place of the removed flower bud in the normal position with morphactin, TIBA and NPA applied in the middle or 1 cm from the base of the excised internode greatly stimulated the elongation, whereas almost no growthpromoting effect of these inhibitors was observed, in comparison to IAA. On the contrary, when IAA was applied on the base of the excised internode in the inverted position, the growth was inhibited, compared to that with lanolin only. The inhibitory effect of auxin was eliminated by the simultaneous application of morphactin, TIBA and NPA placed in the middle of the excised internode. These results suggest that auxin levels in the excised internode regulated by auxin polar transport play a crucial role in the regulation of its elongation growth.

BIOLOGICAL ACTIVITY OF GUMS INDUCED IN TULIP (TULIPA GESNERIANA L.) BY FUSARIUM OXYSPORUM F. SP. TULIPAE, ETHYLENE AND JASMONATES

It is well known that Fusarium oxysporum f. sp. tulipae (Fot), ethylene and jasmonates have a promoting effect on gum induction and its accumulation in tulip (Tulipa gesneriana L.) bulbs. The induction and production of gums are suggested to be regulated by a signal network of jasmonates and ethylene, especially by cross-talk between them. Tulip gums consist of glucuronoarabinoxylan with an average molecular weight of approximately 700 kDa. In this review some biological activity of tulip gums is presented. It is believed that gums have a function in limiting the spread of fungal and bacterial pathogens and insects by isolating the infected tissues. It was found that the addition of tulip gums at a concentration of 5 mg•cm3 to Czapek-Dox-Agar, Malt-Extract-Agar and Potato-Dextrose-Agar greatly stimulated mycelium growth of Fusarium oxysporum f. sp. tulipae and sporulation of the pathogen. Addition of tulip gums to the Czapek-Dox-Broth caused that the pathogen secreted the polysaccharide gum degrading enzymes. In further studies it was found that tulip gums induced by Fusarium oxysporum f. sp. tulipae, ethylene or jasmonates elicited red coloured secondary metabolite(s) in mycelium of the pathogen. The effect of homogenate of different tulip organs (scales, leaves, stem, pistils and roots), applied alone and simultaneously with tulip gums, on red pigment formation by mycelium of F. oxysporum f. sp. tulipae was investigated. It is interesting that a homogenate of tulip scales and pistils almost totally inhibited the formation of the red coloured pigment induced by tulip gums in the mycelium of Fot. It is possible that the polysaccharide of tulip gums, which is glucuronoarabinoxylan, may act as an elicitor that regulates some physiological and biochemical processes connected or responsible for mycelium growth of the Fusarium oxysporum f. sp. tulipae and induction of secondary metabolites by mycelium of the pathogen.