Abstract
Prunus persica fruits were removed from 1-year-old shoots to analysis photosynthesis, chlorophyll fluorescence and genes changes in leaves to low sink demand caused by fruit removal (−fruit) during the final stage of rapid fruit growth. A decline in net photosynthesis rate was observed, accompanied with a decrease in stomatal conductance. The intercellular CO2 concentrations and leaf temperature increased as compared with a normal fruit load (+fruit). Moreover, low sink demand significantly inhibited the donor side and the reaction center of photosystem II. 382 genes in leaf with an absolute fold change ≥1 change in expression level, representing 116 up- and 266 down-regulated genes except for unknown transcripts. Among these, 25 genes for photosynthesis were down-regulated, 69 stress and 19 redox related genes up-regulated under the low sink demand. These studies revealed high leaf temperature may result in a decline of net photosynthesis rate through down-regulation in photosynthetic related genes and up-regulation in redox and stress related genes, especially heat shock proteins genes. The complex changes in genes at the transcriptional level under low sink demand provided useful starting points for in-depth analyses of source-sink relationship in P. persica.
Highlights
Photosynthesis is the basis of plant growth and development, and it plays a decisive role in crop yield and quality
We studied the changes in photosynthesis and chlorophyll fluorescence parameters in P. persica leaves under normal sink demand and low sink demand by fruit removal
We further investigated the relationship between photosynthesis rate (Pn) decline and electron transport chain of photosystem II (PSII) under the low demand by chlorophyll a fluorescence kinetics transient (OJIP-test)
Summary
Photosynthesis is the basis of plant growth and development, and it plays a decisive role in crop yield and quality. The fruit is the most important sink organ for most horticultural plants. The presence or absence of the fruits has a significant effect on source leaf photosynthesis in many plant species including peach (Duan et al, 2008). Fruit removal has often been used to change the sink–source relationship in order to study photosynthetic responses under low sink demand.
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