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At least 19 recordsLinked to original sources
PubMed1994

Modification of flower color in florist's chrysanthemum: production of a white-flowering variety through molecular genetics.

Chimeric chalcone synthase (CHS) constructs were prepared in both anti-sense and sense orientations, and introduced into the chrysanthemum cultivar Moneymaker, along with a T-DNA vector lacking a CHS construct. For both the anti-sense and sense constructs, the majority of the plants produced pink flowers typical of Moneymaker itself. Of 133 sense and 83 anti-sense transgenic individuals 3 of each set produced fully white or very pale pink flowers. No white-flowering transgenic plants were obtained in control transformations. The white flowers were found to accumulate higher levels of chalcone synthase precursors and to have reduced levels of chalcone synthase message. A small-scale field trial was performed to evaluate the stability of the phenotype throughout a series of vegetative propagation steps and during plant growth. The white-flowering trait was maintained well through vegetative propagation; however, during growth of individual white-flowering plants, some pink color was found in some flowers. At one site 2% of the white-flowering plants produced a few pink flowers; at two other sites, as many as 10-12% of the plants produced pale pink flowers.

Acyltransferases↗
PubMed2026

The Jumonji C domain-containing proteins GmJMJ19 and GmJMJ20 link florigen signaling with epigenetic regulation of photoperiodic flowering and post-flowering plant height in soybean.

Soybean (Glycine max) is a photoperiod-sensitive legume whose latitudinal adaptation depends on the precise control of flowering time and plant height. Histone demethylases of the JmjC domain-containing (JMJ) protein family have been implicated in these processes across plant species, but their specific roles in soybean remain largely unexplored. Here, we identify soybean GmJMJ19 and GmJMJ20, two closely related JMJD5/KDM8 orthologs, as master epigenetic regulators that coordinately control both photoperiodic flowering and post-flowering plant height. Both genes exhibit intrinsic, rhythmic expression peaking at ZT12, and their encoded proteins physically interact with the florigen proteins FT2a and FT5a. Loss-of-function mutants display delayed flowering under long days (LDs) and increased plant height under both LDs and short days (SDs), whereas overexpression phenocopies the mutant flowering phenotype, indicating revealing a critical dosage requirement for proper function. Mechanistically, GmJMJ19 and GmJMJ20 are recruited by the FT/FD transcriptional complex to directly activate AP1a and AP1c expression through chromatin modulation. Population genomic analyses reveal distinct selection signatures: GmJMJ19 underwent sustained directional selection during cultivation, whereas GmJMJ20 experienced an early domestication sweep with limited subsequent change. Haplotype analysis identifies coordinated latitudinal clines, with the JMJ19H1/JMJ20H1 combination predominating at high latitudes to promote early flowering and limit height, while JMJ19H2/JMJ20H2 and wild JMJ19H3/JMJ20H3 alleles prevail at low latitudes, conferring later flowering and increased height. Collectively, our findings establish GmJMJ19 and GmJMJ20 as central chromatin regulators linking florigen signaling to downstream target expression and provide valuable allelic resources for breeding regionally adapted soybean varieties across a wide range of latitudinal environments.

Histone modulation↗
PubMed1995

Inhibition of flower formation by antisense repression of mitochondrial citrate synthase in transgenic potato plants leads to a specific disintegration of the ovary tissues of flowers.

The tricarboxylic acid (TCA) cycle constitutes a major component of the mitochondrial metabolism of eucaryotes, including higher plants. To analyze the importance of this pathway, we down-regulated mitochondrial citrate synthase (mCS; EC 4.1.3.7), the first enzyme of the TCA cycle, in transgenic potato plants using an antisense RNA approach. Several transformants were identified with reduced citrate synthase activity (down to approximately 6% of wild-type activity). These plants were indistinguishable from wild-type plants in the greenhouse during vegetative growth. A major change, however, was seen upon initiation of the generative phase (flower formation). In the case of transgenic plants with a strong reduction in citrate synthase activity (< 30% of wild-type levels), flower buds formed > 2 weeks later as compared with wild-type plants. Furthermore, flower buds from these plants did not develop into mature flowers but rather were aborted at an early stage of development. Microscopic analysis showed that in these cases ovaries disintegrated during flower development. We conclude that the TCA cycle is of major importance during the transition from the vegetative to the generative phase.

Citrate (si)-Synthase↗
PubMed1991

A flourishing time for flower development. Workshop on Flower Development, sponsored by Fundación Juan March, Madrid, Spain, March 11-13, 1991.

Molecular genetics has recently erupted in the field of flower development, an area of research traditionally cultivated by plant physiologists. The isolation and molecular characterization of seven homeotic genes (four in Antirrhinum majus and three in Arabidopsis thaliana) that control both floral organogenesis and the transition from inflorescences to floral meristems is leading to major breakthroughs in the understanding of the mechanisms governing flower development. This has already had a great impact among plant physiologists, who are incorporating mutant analysis into studies of floral induction and flower development. We are still missing data about the nature of the pollen product of the S-locus in self-incompatibility systems, although current experimental approaches might provide this information in the near future. Gene technology appears to have a high potential in hybrid seed production through the construction of male sterile plants as well as of plants able to restore fertility. The study of genes regulating pigment formation in flowers continues to provide interesting data on gene expression in plants, in which phenomena such as co-suppression and methylation seem to play an important role. Altogether, one can predict that very exciting times are coming in the field of flower development.

Gene Expression Regulation↗
PubMed1995

QTL analysis of flowering time in Arabidopsis thaliana.

Quantitative trait loci (QTL) analyses based on restriction fragment length polymorphism maps have been used to resolve the genetic control of flowering time in a cross between two Arabidopsis thaliana ecotypes H51 and Landsberg erecta, differing widely in flowering time. Five quantitative trait loci affecting flowering time were identified in this cross (RLN1-5), four of which are located in regions containing mutations or loci previously identified as conferring a late-flowering phenotype. One of these loci is coincident with the FRI locus identified as the major determinant for late flowering and vernalization responsiveness in the Arabidopsis ecotype Stockholm. RLN5, which maps to the lower half of chromosome five (between markers mi69 and m233), only affected flowering time significantly under short day conditions following a vernalization period. The late-flowering phenotype of H51 compared to Landsberg erecta was due to alleles conferring late flowering at only two of the five loci. At the three other loci, H51 possessed alleles conferring early flowering in comparison to those of Landsberg erecta. Combinations of alleles conferring early and late flowering from both parents accounted for the transgressive segregation of flowering time observed within the F2 population. Three QTL, RLN1, RLN2 and RLN3 displayed significant genotype-by-environment interactions for flowering time. A significant interaction between alleles at RLN3 and RLN4 was detected.

Alleles↗
PubMed1995

Flowering responses to altered expression of phytochrome in mutants and transgenic lines of Arabidopsis thaliana (L.) Heynh.

The long-day plant Arabidopsis thaliana (L.) Heynh. flowers early in response to brief end-of-day (EOD) exposures to far-red light (FR) following a fluorescent short day of 8 h. FR promotion of flowering was nullified by subsequent brief red light (R) EOD exposure, indicating phytochrome involvement. The EOD response to R or FR is a robust measure of phytochrome action. Along with their wild-type (WT) parents, mutants deficient in either phytochrome A or B responded similarly to the EOD treatments. Thus, neither phytochrome A nor B exclusively regulated flowering, although phytochrome B controlled hypocotyl elongation. Perhaps a third phytochrome species is important for the EOD responses of the mutants and/or their flowering is regulated by the amount of the FR-absorbing form of phytochrome, irrespective of the phytochrome species. Overexpression of phytochrome A or phytochrome B resulted in differing photoperiod and EOD responses among the genotypes. The day-neutral overexpressor of phytochrome A had an EOD response similar to all of the mutants and WTs, whereas R EOD exposure promoted flowering in the overexpressor of phytochrome B and FR EOD exposure inhibited this promotion. The comparisons between relative flowering times and leaf numbers at flowering of the over-expressors and their WTs were not consistent across photoperiods and light treatments, although both phytochromes A and B contributed to regulating flowering of the transgenic plants.

Arabidopsis↗
PubMed1986

The flowering process as an example of plastic development.

The field of flowering has been characterized by simplistic ideas, as exemplified by the attempts to classify plants on the basis of the kinds of environmental factors required for their transition to flower initiation and the claims that the process of flower formation in photoperiodic and cold-requiring plants is independent of correlative influences from various organs, e.g. the roots. Other examples of this simplified picture are the concept of a specific leaf-generated floral hormone and floral inhibitor and the search at the level of the meristem of a specific evocational event which would set in motion the whole sequence of other events and commit the meristem to flower initiation. Finally, there is the belief that because flower morphology is basis to species classification the morphogenesis of flowers is a rather invariable process. All these ideas are essentially erroneous and it is shown that all aspects of the flowering process are much more flexible than is usually believed. Floral induction may be completed by many, if not all, plants in several alternative sets of environmental factors. At least in some plants, the alternative inductive factors are perceived by different organs, indicating that these factors affect most probably entirely different processes. Thus, at induction, plasticity is extremely large and the fate of any shoot meristem appears to be controlled by a complex and flexible array of promoters and inhibitors arising from all plant parts. At meristem evocation, there are a number of events which are fundamentally the same in many plants, but so far no single initial critical event has been found. The various evocational changes appear to form sets of interconnected systems and this complex network seems to embody some plasticity since it has been possible to suppress experimentally some of the most universal evocational events or alter their temporal order without impairing evocation itself. At later stages, it has been observed that all the morphological characters of inflorescences and flowers may be experimentally altered. However, if the occasional and extreme malformations (monstrosities) caused by some growth substances are excluded, morphogenetic processes do not appear flexible to the point that the reproductive structures of one species are transformed into those of a taxonomically unrelated species. Thus, despite the fact that these processes are never absolutely fixed, plasticity at morphogenesis appears less than that at induction.(ABSTRACT TRUNCATED AT 400 WORDS)

Light↗