Flower development and a functional analysis of related genes in Impatiens uliginosa

Abstract

Impatiens uliginosa is a plant of the Impatiens, with peculiar flowers. In this study, we combined morphogenesis and molecular biology to explore its development of flowers. An analysis of basic observational data and paraffin sectioning showed that it took approximately 13 d for the floral organs to differentiate. An analysis of the development of inflorescences and floral organs by scanning electron microscopy showed that the inflorescence of I. uliginosa is a spiral raceme. The floral organs differentiated in the following order: lateral sepals (Ls), posterior sepal (Ps), anterior sepals (As), anterior petal (Ap), lateral petals (Lp), stamens (St) and gynoecium (Gy). I. uliginosa was found to have four sepals, and the connate stamens are caused by the fusion and growth of filament appendages. The results of fluorescence quantification and virus-induced gene silencing showed that I. uliginosa had its own unique model for flower development, and there was functional diversity of IuAP1 and IuDEF. Among them, IuAP1 controls the formation of bract s (Br), regulates the morphogenesis of posterior sepal, controls the anthocyanin precipitation of the anterior petals and the formation of lateral petals. IuDEF regulates the morphogenesis of lateral sepals, the length of development of the spur, and controls the size of yellow flower color plaques of the lateral petals. In this study, the process of flower development and the function of flower development genes of I. uliginosa were preliminarily verified. This study provides basic guidance and new concepts that can be used to study the development of Impatiens flowers.

Keywords: Impatiens uliginosa; SEM; floral development; floral development genes; floral development model; function of IuAP1 and IuDEF.

Figure 1

Analysis of the characteristics of flower development time in I. uliginosa. (A) Reference diagram of period S1-S8 of I. uliginosa. The ruler is 1 cm. (B) Statistical chart of the duration from S1 to S8. (C) Paraffin sections of the S1-S4 period. S3-2 and S4-1 are horizontal slices, while the rest are longitudinal slices; Fb, Flower buds; Lb, Leaf bud; Br, Bract; Ls, Lateral sepals; Ps, Posterior sepal; Ap, Anterior petal; Lp, lateral petals; St, Stamens; Gy, Gynoecium; Fa, floral apex. (D) Paraffin sections of flower buds in the S4-S6 period. Fi, Filament; Fi*, Filament appendage; An, Anther; Po, Pollens; Pos: Pollen sac wall.

Figure 2

Inflorescence development map of I. uliginosa. Br, Bract; Ls, Lateral sepals; F, Inflorescence apex. (A–C) Characteristics of Bract primordium differentiation. (D) Initial differentiation diagram of Sepals primordium. (E) Early inflorescence diagram.

Figure 3

Floral organ primordium development map of I. uliginosa. (A) Primordium of Lateral sepals. (B) Primordium of Posterior sepal. (C, D) Primordium of Anterior sepals. (E) Primordium of Anterior petal and Lateral petals. (F, G) Primordium of Stamens. (H–J) Primordium of Gynoecium. Ls, Lateral sepals; Ps, Posterior sepal; As, Anterior sepals; Ap, Anterior petal; Lp, Lateral petals; Ulp, Upper lateral petals; Llp, Lower lateral petals; St, Stamens; Gy, Gynoecium; Fa, floral apex; Pi, Pistils; Ov, Ovary; Ca, Carpels; Cc, Central column.

Figure 4

Diagram of the anatomy and plane models of I. uliginosa. (A) Flower anatomy diagram.1: Lateral sepals; 2: Posterior sepal; 3: Anterior sepals; 4: Anterior petal; 5: Upper and Lower lateral petals; 6: Androgynous group. (B) Flower plane model diagram. Ls, Lateral sepals; Ps, Posterior sepal; As, Anterior sepals; Ap, Anterior petal; Ulp, Upper lateral petals; Llp, Lower lateral petals; St, Stamens; Gy, Gynoecium.

Figure 5

Structural characteristics of the filament appendages and stamens. (A, B) Characteristics of Filament appendages. (C) Filament appendages connate. (D, E) Location characteristics of Filaments and Filament appendages. (F) Mature Stamen model diagram. Fi, filaments; Fi*, filament appendages; Gy, gynoecium; An, anthers; St, stamens.

Figure 6

Chart of the analytical expression of the quantitative fluorescence. (A) Analysis of relative gene expression. (B) Analysis of gene importance. * significant. More asterisks indicate enhanced usefulness of the gene. (C) Expression of the heat map. (D) Analysis of the location of gene expression. Ls, Lateral sepals; Ps, Posterior sepal; As, Anterior sepals; Ap, Anterior petal; Ulp, Upper lateral petals; Llp, Lower lateral petals; St, Stamens; Gy, Gynoecium.

Figure 7

The effect of IuAP1 on the development of I uliginosa. (A, B) Characteristics of Bract development. (C, D) The difference of flower morphology. (E) Differences in the morphology of Lateral sepals. (F) Differences in the morphology of Posterior sepal. (G) Differences in the morphology of Anterior petal. (H) Differences in the morphology of Lateral petals. WT, Wild type; # IuA1, VIGS-IuAP1.

Figure 8

Effect of IuDEF on the development of I. uliginosa. (A, B) The difference of flower morphology. (C) Spur length. (D) Differences in the morphology of Lateral sepals. (E) Differences in the morphology of Anterior petal. (F) Differences in the morphology of Lateral petals. WT, Wild type; # IuAP1, VIGS-IuDEF.

Figure 9

ABCDE model for the Development of Arabidopsis thaliana and I. uliginosa.