Genes that Alter Senescence in Response to Environmental Factors

One of the unique properties of plant growth and development is that it is highly influenced by environmental conditions. This may be an evolutionary strategy for a sessile organism to cope with environmental fluctuations. Senescence is an integrated response of plants to external environmental factors as well as to endogenous developmental signals. Thus, at least some genes that are involved in environmental response are expected to alter senescence.

A. Genes in Light Signaling

Light is perceived by a variety of photoreceptors and affects plant developmental processes throughout the life span, including germination, chloroplast development, seedling establishment, and flowering time (Quail, 1991; Furuya, 1993). Light control of senescence is covered in detail in Chapter 26. The light effects on senescence may be direct or indirect as with photoperiod effects on reproductive development (see Section VI below). Several genetic constructs also provide evidence that light can play a direct role (Jordan et al, 1995; Thiele etal., 1999).

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