Sepallata genes, known as SEP genes, are MADS-box transcription factors essential for specifying floral organ identity beyond sepals in the ABCDE model of flower development. They fall under the E genes category of homeotic genes.

Question Analysis

The query tests knowledge of the ABCDE model, where floral homeotic genes (A, B, C, D, E) combinatorially determine organ identity in whorls: sepals (A), petals (A+B+E), stamens (B+C+E), carpels (C+E), and ovules (D+E). SEP genes (SEP1-4 in Arabidopsis) act redundantly as E-class genes, forming complexes with A/B/C proteins; their quadruple mutants convert all inner organs to leaves.

Option Breakdown

• A genes: Specify sepals alone (e.g., AP1, AP2); SEP genes are not primary for sepals and transform petals/stamens/carpels to sepals in mutants. Incorrect.

• B genes: Combine with A for petals (A+B+E) and C for stamens (B+C+E) (e.g., AP3, PI); SEP provides the E function, not B. Incorrect.

• D genes: Specify ovules within carpels (e.g., SHATTERPROOF); SEP aids ovules but is distinctly E-class. Incorrect.​

• E genes: Correct; SEP1-SEP4 define E-class, essential for petals, stamens, carpels (not sepals); mutations confirm this (sep1/2/3 triple: inner organs to sepals; quadruple: all to leaves).

Answer: E genes.​

Sepallata genes, key E genes in the homeotic framework, drive normal development of floral organs like petals, stamens, and carpels. This Sepallata genes are considered essential for normal development of floral organs guide explores their classification, functions, and exam relevance.

ABCDE Model Basics

Floral organs form via combinatorial action: A (sepals), A+B+E (petals), B+C+E (stamens), C+E (carpels). SEPALLATA (SEP1-4) MADS-box genes provide E-function, enabling complexes for inner whorls. Quadruple sep mutants yield leaf-like flowers, proving indispensability.

Why E Genes, Not Others?

Mutations and Evidence

SEP1/2/3 triple mutants convert petals/stamens/carpels to sepals; adding SEP4 affects all whorls. This underscores Sepallata genes E homeotic genes specificity for non-sepal organs in Arabidopsis and beyond.