Puzzle Box, a Tobacco Line with Flowers that Mix Floral and Inflorescence Characteristics

Trull, Melanie C.; Malmberg, Russell L.

doi:10.2307/2445733

“…The correlation of plastochron and heterochrony is also suggested by the puzzle box mutant of tobacco, which shows a random plastochron and is considered to show heterochrony in the reproductive phase (Trull and Malmberg, 1994). It may be that developmental rate affects the duration of the developmental phase.…”

Section: Discussion Pla1 Is a Unique Heterochronic Mutationmentioning

confidence: 90%

A Recessive Heterochronic Mutation, plastochron1, Shortens the Plastochron and Elongates the Vegetative Phase in Rice

Itoh

¹

,

Hasegawa

²

,

Kitano

³

et al. 1998

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We describe two recessive alleles of a rice heterochronic gene, plastochron1-1 ( pla1-1 ) and pla1-2 , that reduce the length of the plastochron to approximately half that of the wild type. Because the onset of the reproductive phase in pla1 was not temporally affected, the number of leaves produced in the vegetative phase was nearly twice that produced in the wild type. Panicle development was severely disturbed in pla1 mutants. In pla1-1 , many primordia of primary rachis branches were converted into vegetative shoots. These ectopic shoots repeated the initiation of panicle development and the conversion of primary rachis branches into shoots. In the weak allele pla1-2 , however, only the basal one or two primordia developed as vegetative shoots, and the remaining primordia developed to produce a truncated panicle. These results indicate that both vegetative and reproductive programs are expressed simultaneously during the reproductive phase of pla1 ; however, the degree varied depending on the strength of the allele. Accordingly, pla1 is a heterochronic mutation that extends the vegetative period. The shoot apical meristem of pla1 was larger than that of the wild type, although the shape was not modified. An in situ hybridization experiment using the histone H4 gene as a probe revealed that cell divisions are accelerated in the pla1 meristem. The PLA1 gene is considered to regulate the duration of the vegetative phase by controlling the rate of leaf production in the meristem. INTRODUCTIONPlant development generally is divided into four distinct phases: embryogenesis, early vegetative phase (juvenile phase), late vegetative phase (adult phase), and reproductive phase (Conway and Poethig, 1993). In almost all plant species, two phase changes are recognized easily by the distinct morphological changes that occur in plants from the embryonic phase to the juvenile vegetative phase and from the adult vegetative phase to the reproductive phase. A clear change between the juvenile and adult vegetative phases has been reported for English ivy, maize, and Arabidopsis (Hackett, 1985;Zimmerman et al., 1985;Poethig, 1988Poethig, , 1990 Lawson and Poethig, 1995;Telfer et al., 1997). However, in several species including rice, the phase change from juvenile to adult is not clear because it is continuous and is not accompanied by gross visible changes.Whatever the case may be, the plant life cycle is driven by phase-specific genetic programs that are partially overlapping (Bongard-Pierce et al., 1996). Mutations that delay or advance phase change have been reported for several plant species. Late-flowering mutants can be interpreted as prolonging the vegetative phase and delaying the reproductive phase. Recently, using trichome distribution or epidermal characters as phase-specific markers, researchers have described several late-flowering and dwarf mutations that prolong the juvenile phase (Evans and Poethig, 1995;Telfer et al., 1997).Heterochronic mutations affecting the timing of developmental events may be of major sig...

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“…Therefore, sho1 affects juvenile shoot architecture but not the phase change. In the puzzle box mutant of tobacco, irregular plastochron and dwarfism have been reported (Trull and Malmberg, 1994). Furthermore, the floral phenotypes of puzzle box mutants suggest that inflorescence and floral programs are expressed together.…”

Section: Introductionmentioning

confidence: 99%

A Recessive Heterochronic Mutation, plastochron1, Shortens the Plastochron and Elongates the Vegetative Phase in Rice

Itoh¹,

Hasegawa²,

Kitano³

et al. 1998

View full text Add to dashboard Cite

We describe two recessive alleles of a rice heterochronic gene, plastochron1-1 (pla1-1) and pla1-2, that reduce the length of the plastochron to approximately half that of the wild type. Because the onset of the reproductive phase in pla1 was not temporally affected, the number of leaves produced in the vegetative phase was nearly twice that produced in the wild type. Panicle development was severely disturbed in pla1 mutants. In pla1-1, many primordia of primary rachis branches were converted into vegetative shoots. These ectopic shoots repeated the initiation of panicle development and the conversion of primary rachis branches into shoots. In the weak allele pla1-2, however, only the basal one or two primordia developed as vegetative shoots, and the remaining primordia developed to produce a truncated panicle. These results indicate that both vegetative and reproductive programs are expressed simultaneously during the reproductive phase of pla1; however, the degree varied depending on the strength of the allele. Accordingly, pla1 is a heterochronic mutation that extends the vegetative period. The shoot apical meristem of pla1 was larger than that of the wild type, although the shape was not modified. An in situ hybridization experiment using the histone H4 gene as a probe revealed that cell divisions are accelerated in the pla1 meristem. The PLA1 gene is considered to regulate the duration of the vegetative phase by controlling the rate of leaf production in the meristem.

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“…In the second whorl petals, the trichomes are confined to the abaxial surface but are restricted to the adaxial side in the homeotic appendages carried by the ZmHoxl transgenic stamens. In addition to petaloid characteristics, transgenic ZmHOxl stamens also often carry a Small cap of stigmatic tissue ( Figure 4F), a phenotype also found in the APfTALA2 mutant of Arabidopsis (Jofuku et al, 1994) or the puzzle box line of tobacco (Trull and Malmberg, 1994).…”

Section: Ectopic Expression Of Either Zmhoxl Gene Disrupts Flower Devmentioning

confidence: 71%

“…Some of the alterations in transgenic ZmHoxl flowers resemble phenotypes associated with the single terminal flower of the tobacco puzzle box mutant (Trull and Malmberg, 1994). These features include the petaloid character of stamen and the development of additional internal floral organs within the fourth whorl.…”

Section: Changes In the Tobacco Flowermentioning

confidence: 98%

Ectopic Expression of the Maize Homeobox Genes ZmHox1a or ZmHox1b Causes Pleiotropic Alterations in the Vegetative and Floral Development of Transgenic Tobacco

Überlacker¹,

Klinge²,

Werr³

1996

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The ZmHox1a and ZmHox1b (for Zea mays homeobox) genes map on chromosomes 8 and 6, respectively. Both homeobox genes encode proteins that show 91% similarity and are transcribed simultaneously in meristematic and proliferating cells of the maize plant. To gain insight into the biological function of these genes, both open reading frames were expressed in tobacco, under the control of the cauliflower mosaic virus 35S promoter. The resulting transgenic ZmHox1a or ZmHox1b plants showed identical phenotypic alterations that fall into three classes: size reduction, formation of adventitious shoots, and homeotic floral transformations. Approximately 30% of the ZmHox1-expressing plants grew to only one-third of the wild-type size, and most axillary buds gave rise to lateral shoots. Flower abnormalities included formation of petaloid stamens and development of secondary flowers within the primary gynoecium. Therefore, the ectopic expression of the maize ZmHox1 homeobox gene products affects the vegetative as well as the reproductive phase of tobacco plants. All phenotypic alterations were transmitted to the next generation.

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Puzzle Box, a Tobacco Line with Flowers that Mix Floral and Inflorescence Characteristics

Cited by 6 publications

References 15 publications

A Recessive Heterochronic Mutation, plastochron1, Shortens the Plastochron and Elongates the Vegetative Phase in Rice

A Recessive Heterochronic Mutation, plastochron1, Shortens the Plastochron and Elongates the Vegetative Phase in Rice

A Recessive Heterochronic Mutation, plastochron1, Shortens the Plastochron and Elongates the Vegetative Phase in Rice

Ectopic Expression of the Maize Homeobox Genes ZmHox1a or ZmHox1b Causes Pleiotropic Alterations in the Vegetative and Floral Development of Transgenic Tobacco

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