Pathways of Photosynthesis in Non-Leaf Tissues

SIMPLE SUMMARY: Plants have leaves that are specialized organs to capture light energy. This energy is used to support photosynthesis, a process in which carbon dioxide from the atmosphere is incorporated into organic compounds in the plant to allow the plant to grow. Other parts of the plant, such as the stem, flowers, or seeds are also able to conduct photosynthesis to contribute to growth in many plant species. The main contribution of photosynthesis in these parts of the plant may be to use carbon dioxide produced by the plant in respiration rather than from the surrounding atmosphere. The biochemical processes used by the plant in these organs may be different from those used in the leaves of the same plant. This process is enhanced in plants under stress and may be important for plant survival in some situations. Increased knowledge of these processes may be used to develop plant varieties that are more tolerant of environmental extremes and could help adapt agriculture to climate change. ABSTRACT: Plants have leaves as specialised organs that capture light energy by photosynthesis. However, photosynthesis is also found in other plant organs. Photosynthesis may be found in the petiole, stems, flowers, fruits, and seeds. All photosynthesis can contribute to the capture of carbon and growth of the plant. The benefit to the plant of photosynthesis in these other tissues or organs may often be associated with the need to re-capture carbon especially in storage organs that have high respiration rates. Some plants that conduct C(3) photosynthesis in the leaves have been reported to use C(4) photosynthesis in petioles, stems, flowers, fruits, or seeds. These pathways of non-leaf photosynthesis may be especially important in supporting plant growth under stress and may be a key contributor to plant growth and survival. Pathways of photosynthesis have directionally evolved many times in different plant lineages in response to environmental selection and may also have differentiated in specific parts of the plant. This consideration may be useful in the breeding of crop plants with enhanced performance in response to climate change.