Number Of Flower Organs Research Articles

Morphobiological features of generative organs of fertile and sterile table beet plants and their variability as a result of self-pollination (review)

Beet is considered a difficult breeding object due to its biological peculiarities that make it difficult to obtain hybrid seed progeny. In cross-pollinated crops, the maximum hybridization is achieved by using sterile mother plants, which are extremely rare in the nature. Inbreeding is one of the ways to isolate genotypes with cytoplasmic male sterility, which are controlled by recessive alleles of nuclear genes and S-factor of mitochondrial DNA, from a complex heterogeneous population. The main distinguishing features allowing to identify plants with male sterility are the structure and coloring of anthers, and the quality composition of pollen. The diversity of phenotypic manifestation of marker coloration in sterile anthers is determined by the ratio of different pigments. Diversity of pollen grains of fertile and sterile plants is caused by differences in their development at the late stages of androgenesis. The degree of sterilization varies in different genotypes, which is associated with complex regulatory mechanisms of interaction between the genetic apparatus of the nucleus and the cytoplasm. Along with abnormalities of pollen grain micropopulations, self-fertilization results in morphological changes in the structure of inflorescences and number of flower organs, which has a direct impact on the seed productivity of plants. The studies summarized in this publication are relevant and essential for the search of effective ways to control plant development in ontogenesis and universal selection criteria in the process of creating fundamentally new forms of plants, which is especially important for breeding.

A MADS-box gene associated with protocorm-like body formation in Rosa canina alters floral organ development in Arabidopsis

We isolated a gene encoding a putative MADS-box protein designated RcAGL15 from a protocorm-like body (PLB), a somatic embryogenetic structure) of Rosa canina L. RcAGL15 encodes a predicted protein of 251 amino acid residues with a molecular weight of 28 kDa and a theoretical isoelectric point of 7.5. Reverse-transcription polymerase chain reaction shows that RcAGL15 is mainly expressed in PLB and regenerated PLB, but not in leaves of aseptic seedlings, incubated leaflets before callus formation, calli, rhizoids, or leaves of regenerated shoots. Transgenic, ectopic expression of RcAGL15 in Arabidopsis changes numbers of floral organs and reduces content of indole-3-acetic acid, but increases levels of abscisic acid. Thus, RcAGL15 appears to be a new MADS-box gene that plays regulatory roles in morphological development and the number of flower organs, as well as somatic embryogenesis.

Spatial pattern formation in the flower of Arabidopsis thaliana: Mathematical modeling

The research into the genetic control of flower formation is a rapidly evolving field of plant developmental biology. An ABC model of the genetic control of floral morphogenesis based on the studies of Arabidopsis thaliana mutants [1] envisaged the flower structure as a pattern comprising four organ whorls, with the particular organ development in each whorl specified by the combined activities of several genes. The expression of the A class genes APETALA1 ( AP1 ) and APETALA2 ( AP2 ) determines for the development of sepals (whorl 1). The development of carpels (whorl 4) is specified by the C class gene AGAMOUS ( AG ). The combined activities of the A and C genes together with the B genes APETALA3 ( AP 3 ) and PISTILLATA ( PI ) specify the development of petals and stamens (whorls 2 and 3, respectively). The ABC model postulates that the mutations in these genes would change the organ specificity in particular whorls. In several ABC mutants, the number of flower organs is changed; therefore a hypothesis was put forward that these genes specify both the identity of flower organs and flower organ initiation [2]. However, the mechanism of such specification is poorly understood. When working out the mathematical model of floral development based on the ABC-model postulates, we found that the existing evidence on the functions of the ABC genes did not sufficiently clarify the nature of changes in the arrangement of flower organs in the mutants. It follows that the processes that determine spatial pattern formation in the flower must be studied in more detail [3]. There are two hypotheses describing the process of spatial pattern formation in the developing flower. The first one presumes that floral development proceeds acropetally, from periphery towards the center [4]. The development of each whorl is triggered by a signal from the whorl on the outside. The second hypothesis maintains that in floral development, the formation of organ spatial pattern precedes the initiation of corresponding organs [5]. Recently Chub and Penin [6] suggested that the spatial patterning may advance both acropetally and basipetally. The present study aimed at elucidating, by mathematic modeling, the basic aspects of spatial flower patterning in order to recognize the effects of the ABC genes on flower organ arrangement. The modeling demonstrated that organ spatial pattern formation in flowers was regularly scheduled and advanced in two directions, acropetally in the perianth and basipetally in the stamens and carpels. We demonstrated that AP2 (class A) and AG (class C) both specified the particular flower organs and also determined the acropetal and basipetal patterning zones in the floral meristem (APZ and BPZ, respectively).