50. In plants gene ‘sepallata’ is NOT involved in formation of organ
    (1) Sepals (2) Petals
    (3) Stamens (4) Carpels

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Introduction

SEPALLATA (SEP) genes are a group of MADS-box transcription factors vital for the proper formation of floral organs in plants. They function mainly as part of the E-class genes in the ABCDE model of flower development, coordinating with other gene classes to specify petals, stamens, and carpels. However, they are not involved in the formation of sepals.

Functions of SEPALLATA Genes in Floral Organogenesis

• SEP genes act redundantly to specify the identity of petals (second whorl), stamens (third whorl), and carpels (fourth whorl).

• They form multimeric protein complexes with A, B, and C class floral homeotic genes critical for organ identity determination and floral meristem development.

• Loss-of-function mutations in SEP genes lead to homeotic transformations where petals, stamens, and carpels are converted to sepal-like organs, evidencing their critical role in specifying these organs.

Distinction from Sepal Development

• Sepal identity is primarily determined by A-class genes (e.g., APETALA1) without direct involvement of SEP genes.

• SEP proteins act as co-factors but not primary determinants for sepals.

Summary of Organ Involvement

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Conclusion

SEPALLATA genes are essential for the development of petals, stamens, and carpels but do not participate in sepal formation, making option (1) sepals the correct answer.