66. Which one of the following options related to plant growth and development is matched correctly?
(1) LEAFY: regulator of genomic imprinting
(2) Xylogenesis: wood formation

(3) FLOWERING LOCUS T (FT)
(4) FLOWERING LOCUS C (FLC)

 

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Introduction

Xylogenesis is the fundamental biological process through which wood, also known as xylem tissue, is formed in plants, particularly in trees and woody shrubs. This complex developmental process involves the production of new xylem cells from the vascular cambium, their growth, and maturation into specialized cells that provide structural support and water conduction.

What is Xylogenesis?

• Xylogenesis occurs in the vascular cambium, a layer of meristematic cells located between the xylem and phloem.

• It involves several stages: cell division (cambial activity), cell expansion, secondary cell wall deposition, and lignification, transforming the cells into mature wood tissue.

• The specialized xylem cells include tracheids, vessel elements, fibers, and parenchyma, all contributing to water transport and mechanical strength.

Importance of Cell Division and Differentiation

• The cambium divides to produce precursor cells that differentiate into xylem cells.

• Cell elongation and enlargement occur prior to secondary wall thickening.

• Lignin deposition strengthens the cell walls and makes the tissue rigid and water-resistant essential for plant support.

Other Gene Functions Listed

• LEAFY is a major floral meristem identity gene, not associated with genomic imprinting.

• FLOWERING LOCUS T (FT) is a key promoter of floral transition, acting as the mobile florigen hormone signal.

• FLOWERING LOCUS C (FLC) is a major floral repressor that delays flowering through vernalization pathways by repressing FT and other flowering promoters.

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Summary Table: Gene/Process and Correct Matching

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Conclusion

Among the options provided, xylogenesis is correctly matched with wood formation. LEAFY is not involved in genomic imprinting, and FLOWERING LOCUS T (FT) and FLOWERING LOCUS C (FLC) regulate flowering processes.