Crop Physiology

Crop Physiology (Second Edition)

Applications for Genetic Improvement and Agronomy
2015, Pages 223-249
Crop Physiology

Chapter 10 - Senescence and crop performance

https://doi.org/10.1016/B978-0-12-417104-6.00010-8Get rights and content

Abstract

Senescence processes are intrinsic to cell fate and the development of tissues, organs and the whole plant. Selective senescence and elimination of cells occur during the differentiation of xylem and other anatomical features, at all stages in the formation and development of reproductive structures, and in response to a changing environment. During senescence of leaves, senescence-associated genes are activated, chlorophyll and proteins are catabolized and there are major modifications to organelle structure and function, under the control of hormones and reactive oxygen species. Senescence contributes to the turnover of root systems and the lifespan of nodules in legumes. Fruit ripening is a form of senescence regulated by specific genes and hormone-mediated signaling pathways. Plants deploy senescence as a strategic adaptation to seasonal environmental change, and as a tactical response to unpredictable abiotic and biotic stresses. Senescence is the point of transition from the carbon capture phase of crop development to the period of remobilization of nitrogen and other nutrients. Source–sink control is exerted through an interaction between sugar-sensing pathways, hormones (notably cytokinins) and autophagic mechanisms of cell development and death. Initiation and execution of the senescence program are regulated by transcription factors, which represent targets for genetic manipulation. Selecting for delayed senescence has improved yield for some crop species but not all; it is a more generally useful trait when associated with selection for stress responses.

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