The Development of Sex Expression in Cucurbit Flowers

Nitsch, J. P.; Kurtz, Edwin B.; Liverman, James L.; Went, F. W.

doi:10.1002/j.1537-2197.1952.tb13042.x

Cited by 111 publications

(56 citation statements)

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“…This and the relatively higher auxin levels found in cucumber plants grown under short day conditions which promote femaleness (Fig. 2) confirm earlier reports (9) and the hypothesis of Nitsch et al (23) that higher auxin level is associated with female sex expression.…”

Section: Effect Of Daylength and Ethephon On Endogenous Auxinsupporting

confidence: 90%

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The Level of Phytohormones in Monoecious and Gynoecious Cucumbers as Affected by Photoperiod and Ethephon

1972

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The endogenous levels of auxin, gibberellin, and inhibitors were followed in monoecious and gynoecious cucumber (Cucumis sativus L.) plants, and in plants treated with the ethylene-releasing compound Ethephon (2-chloroethyl phosphonic acid). Higher auxin inhibitor and lower gibberellin levels were associated with female tendency. The endogenous level of gibberellin and auxin decreased in Ethephon-treated plants. Appli (33). When ethylene evolution from cucumber plants was examined, more ethylene was evolved from apices of the gynoecious than from those of monoecious type (28).The interactions between auxin and ethylene are complex. Many studies have shown that auxins hasten the production of ethylene (1,6,8), that ethylene enhances the decomposition of auxin (3), and that it also inhibits the movement of auxin in the plant (3). A number of effects, in the past attributed to high levels of auxin, are now considered to be a result of ethylene production under the influence of auxin (5, 7).Little is known about the interaction between ethylene and gibberellin. Antagonism between them has been found in germination of wheat and the production of both a-amylase and invertase (31). Their action is also antagonistic in fruit ripening and in sex expression of flowers (13, 26). We are not aware of any publication on the effect of ethylene on endogenous gibberellin levels. Kang et al. (18) found that gibberellin had no effect on ethylene production in bean seedlings. They concluded that GA and ethylene effects in the development of the seedlings were independent.Since sex expression in cucumbers is influenced by Ethephon as well as by auxin and gibberellin, we tried to determine in the present work the effect of Ethephon on the level of the above phytohormones as well as on ABA and other native inhibitors, in an attempt to gain additional knowledge on the relation of these phytohormones to sex expression.MATERIALS AND METHODS Plant Material. Endogenous levels of growth substances were determined in the monoecious and gynoecious 'Bet Alpha' 2 lines of cucumber (Cucuinis sativus L.) plants. The gynoecious line was bred from the monoecious one and differs from it in the gene for femaleness (2). Under short day conditions it produces female flowers from the first or second node, under long day conditions male flowers are produced at the first six nodes, all the rest being female. In one experiment andromonoecious muskmelon plants (cv. Ananas PMR) were used.In most experiments plants were grown in growth chambers at 8-hr photoperiod under mixed fluorescent and incandescent lamp light of 3500 ft-c. Long day treatments were given by incandescent lamps of 70 to 80 ft-c. Temperature during the day, 8 hr, was 28 C, at all other times it was 18 C. In some experiments CO2 level was also controlled in the chambers.In a few experiments plants were grown in a phytotron under natural light intensities. Long days were given by extending the natural day to 16 hr by incandescent lamps of 100 ft-c.

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Section: Effect Of Daylength and Ethephon On Endogenous Auxinsupporting

confidence: 90%

“…Addition of IAA to these cultures produced ovaries and stigmas. Short days and low temperatures enhanced the femaleness of certain cucumber cultivars (20) and of squash (23). Nitsch et al (23) assume that this was due to high levels of endogenous auxin found under short day conditions.…”

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confidence: 99%

The Level of Phytohormones in Monoecious and Gynoecious Cucumbers as Affected by Photoperiod and Ethephon

1972

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“…Ovaries capable of setting parthenocarpic fruit have been assumed to contain higher auxin at anthesis than ovaries of cultivars that require fertilization for fruit growth (12). But, the present study showed that a non-parthenocarpic cultivar, 'Mogami' ovaries contained the same IAA level as a parthenocarpic one, `Chojitsu-Ochiai No.2', at 3 days after anthesis.…”

Section: Introductioncontrasting

confidence: 63%

Fruit Growth Induced by Benzyladenine in Cucumis sativus L.: Influence of Benzyladenine on Cell Division, Cell Enlargement and Indole-3-acetic Acid Content.

Takeno

Ise

Minowa

et al. 1992

Engei Gakkai zasshi

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“…Por outro lado, a protandria constatada no início da floração, também registrada em outras espécies de Cucurbitaceae, como nos gêneros Cucurbita e Cucumis (Nitsch et al 1952) poderia estar dificultando, mas não impedindo a ocorrência da autopolinização. De qualquer maneira, a espécie necessita de agentes bióticos para o transporte do pólen, fato constatado pela ausência de frutificação no teste de anemofilia.…”

Section: Discussionunclassified

“…Outra explicação para tal fato, poderia ser embasada novamente na hipótese de que a abertura das flores femininas, que se inicia posteriormente das flores masculinas, seria favorecida pelo condicionamento dos visitantes, assegurando o sucesso reprodutivo da espécie (Piratelli et al 1998). Em cucurbitáceas, é comum flores masculinas serem mais numerosas, principalmente no início da floração, porém essa proporção pode ser alterada por mudanças climáticas, ou redução do fotoperíodo que tendem a aumentar o número de flores femininas (Nitsch et al 1952, Rust et al 2003. Marchini et al 2001 já haviam percebido um padrão descontínuo de florescimento em Momordica charantia, o que corrobora os resultados aqui apresentados.…”

Section: Discussionunclassified

Ecologia da polinização de Momordica charantia L. (Cucurbitaceae), em Florianópolis, SC, Brasil

2005

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-(Pollination ecology of Momordica charantia L. (Cucurbitaceae) in Florianópolis, SC, Brazil). Bitter melon is a monoecious and ruderal species of economic interest. The knowledge of its reproductive mechanisms is important for its conservation and management. The species floral biology, reproductive phenology, pollination, and breeding system were studied. The species has diclinous flowers, with diurnal anthesis. The period of flowering lasted around 100 days and its peak occurred in October. In the beginning of the flowering the species presents dicogamy of the protandry type. The female flowers do not produce nectar, while the male flowers produce nectar during the entire period of anthesis. There was identified a mimicry of the male flowers by the female flowers. Fruit formation occurred through crossed-pollination and self-pollination. The number of seeds in the fruits did not differ (H = 1.13; P > 0.05) among the type of pollination. The relation seed/egg was in the order of 80%. All floral visitors collected and observed on the flowers belong to the class Insecta. Diabrotica speciosa (Coleoptera, Chrysomelidae) was the most abundant species (40%) and the main pollinator of Momordica charantia in the study area. Other insects, however, as bees (Apoidea) and butterflies (Hesperiidae and Pieridae), were also observed in the flowers and can contribute as pollinators.Key words -bitter melon, breeding system, floral biology, pollination RESUMO -(Ecologia da polinização de Momordica charantia L. (Cucurbitaceae), em Florianópolis, SC, Brasil). O melão-desão-caetano é uma espécie monóica e ruderal de interesse econômico. O conhecimento de seus mecanismos reprodutivos é fundamental para a sua conservação e manejo. Foram estudados a biologia floral, a fenologia reprodutiva, a polinização e o sistema de reprodução da espécie. A espécie possui flores diclinas, com antese diurna. O período de floração dura em torno de 100 dias e seu pico ocorre em outubro. No início da floração a espécie apresenta dicogamia do tipo protandria. As flores femininas não produzem néctar, tendo sido identificado mimetismo das flores masculinas pelas femininas. As flores masculinas produziram néctar durante todo o período de antese. Houve formação de frutos por fecundação cruzada e autopolinização. O número de sementes presentes nos frutos não diferiu (H = 1,13; P > 0,05). A relação sementes/óvulos foi da ordem de 80%. Todos os visitantes florais coletados e observados pertencem à Classe Insecta. Diabrotica speciosa (Coleoptera, Chrysomelidae) foi a espécie mais abundante (40%) e o principal polinizador de Momordica charantia na área de estudo. Outros insetos, como abelhas (Apoidea) e lepidópteros (Hesperiidae e Pieridae), também visitaram as flores e podem contribuir na polinização.Palavras-chave -biologia floral, melão-de-são-caetano, polinização, sistema reprodutivo

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The Development of Sex Expression in Cucurbit Flowers

Cited by 111 publications

References 18 publications

The Level of Phytohormones in Monoecious and Gynoecious Cucumbers as Affected by Photoperiod and Ethephon

The Level of Phytohormones in Monoecious and Gynoecious Cucumbers as Affected by Photoperiod and Ethephon

Fruit Growth Induced by Benzyladenine in Cucumis sativus L.: Influence of Benzyladenine on Cell Division, Cell Enlargement and Indole-3-acetic Acid Content.

Ecologia da polinização de Momordica charantia L. (Cucurbitaceae), em Florianópolis, SC, Brasil

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