Preferential reproduction mode of hermaphrodite papaya plant (Carica papaya L; Caricaceae)

Abstract

-This research was done to study the reproductive system of papaya hermaphrodite plant based on the histochemical nature of pollen grain, stigma receptivity, in vivo pollen grain germination and pollen:ovule ratio. In the histochemical analysis, pollen grains were stained by using Sudan IV and I 2 KI solution; the stigma receptivity was assessed by alpha-naphthtyl acetate solution in closed and opened flowers. Pollen germination and pollen tube growing were examined in flower buds near anthesis with 0.1% aniline blue. To estimate the pollen:ovule ratio , anthers from each flower bud were dissected and all pollen grains were counted; ovules were dissected from ovaries and were counted under stereomicroscope. The results indicated that papaya pollen grains are of lipidic nature; the stigmas were receptive before the opening and until 48 hours after opening; the pollen grains germinated and emitted polinic tube before flower opening and the pollen:ovule ratio indicated the predominance of autogamous reproductive system. These results indicate that hermaphrodite papaya trees is preferentially of optional autogamous with cleistogamy. Index terms: Carica papaya, cleistogamy, autogamy, pollen grain histochemistry, P:O ratio, stigma receptivity. MODO DE REPRODUÇÃO PREFERENCIAL DE PLANTAS HERMAFRODITAS DE MAMOEIRO (Carica papaya L; Caricaceae)RESUMO -Esta pesquisa teve o objetivo de estudar o sistema reprodutivo preferencial de plantas hermafroditas de mamoeiro, com base na natureza histoquímica dos grãos de pólen, receptividade do estigma, teste de germinação in vivo do grão de pólen e razão pólen : óvulo. Na análise histoquímica dos grãos de pólen, foram utilizados os corantes Sudan IV e solução de I 2 KI; a receptividade do estigma foi avaliada com a solução de acetato de alfa-naftil em flores abertas e fechadas. A germinação e o crescimento do tubo polínico in vivo foram avaliados em flores fechadas, utilizando solução de azul de anilina a 0,1%. Para estimar a razão pólen:óvulo, anteras de cada flor foram dissecadas, e os grãos de pólen foram contados; ovários foram dissecados, e os óvulos foram contados sob estereomicroscópio. Os resultados indicaram que os grãos de pólen do mamoeiro são de natureza lipídica; os estigmas estavam receptivos antes da abertura e até 48 h após a abertura; os grãos de pólen germinaram e emitiram tubo polínico antes da abertura floral, e a relação pólen:óvulo, indicou predominância do sistema reprodutivo autógamo. Esses resultados indicaram que o modo de reprodução preferencial do mamoeiro hermafrodita é autógamo facultativo com cleistogamia. Termos para indexação: Carica papaya, cleistogamia, autogamia, histoquímica de grãos de pólen, relação P : O, receptividade de estigma.

Stigma structure and receptivity in papaya (Carica papaya L.)

“…Parés et al (2002) reported that in papaya plants, the stigmas can remain receptive for up to three days after anthesis, and the efficiency of artificial pollination was better in the first 48 hours after floral opening. Similar results were observed by Damasceno Júnior et al (2009), who reported greater stigma receptivity of papaya soon after anthesis, with receptivity continuing for up to 48 hours after floral opening.…”

The Mating System of the Wild-to-Domesticated Complex of Gossypium hirsutum L. Is Mixed

“…Some crops have multiple mating systems, such as domesticated ‘Maradol’ ( Carica papaya ), which is hermaphroditic, while native varieties and wild papayas are dioecious ( Carvalho and Renner, 2012 ). Importantly, the characterization of the mating system of many plant species has been biased toward the domesticated counterparts, because only a sub-sample of the wild-to-domesticated complex was used (e.g., Carica papaya ( Damasceno et al, 2009 ), Persea americana ( Ish-Am et al, 1999 ), Piper nigrum ( Thangaselvabal et al, 2008 ). This bias may have profound consequences for the conservation of conspecific wild relatives, especially because conclusions drawn from studies with domesticated varieties are extrapolated to the whole species, failing to consider the genotypic and phenotypic diversity that wild relatives possess.…”

Twenty-Two-Year Papaya Breeding Program: From Breeding Strategy Establishment to Cultivar Development

“…Hermaphrodite plants are typically used for commercial cultivation, which makes it important to understand their means of reproduction. The results indicated that the preferential means of reproduction of hermaphrodite papaya is facultative autogamous with cleistogamy (Damasceno Junior et al, 2009b).…”