Abstract
Previous studies have revealed a significant genetic relationship between phosphorus (P)-efficiency and photosynthesis-related traits in soybean. In this study, we used proteome profiling in combination with expression analysis, biochemical investigations, and leaf ultrastructural analysis to identify the underlying physiological and molecular responses. The expression analysis and ultrastructural analysis showed that the photosynthesis key genes were decreased at transcript levels and the leaf mesophyll and chloroplast were severely damaged after low-P stress. Approximately 55 protein spots showed changes under low-P condition by mass spectrometry, of which 17 were involved in various photosynthetic processes. Further analysis revealed the depression of photosynthesis caused by low-P stress mainly involves the regulation of leaf structure, adenosine triphosphate (ATP) synthesis, absorption and transportation of CO2, photosynthetic electron transport, production of assimilatory power, and levels of enzymes related to the Calvin cycle. In summary, our findings indicated that the existence of a stringent relationship between P supply and the genomic control of photosynthesis in soybean. As an important strategy to protect soybean photosynthesis, P could maintain the stability of cell structure, up-regulate the enzymes’ activities, recover the process of photosystem II (PSII), and induce the expression of low-P responsive genes and proteins.
Highlights
Crop growth and yield formation rely on photosynthesis, but the photosynthetic process largely relies on phosphorus (P) and P-containing compounds [1,2]
We found that P deficiency significantly decreased the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), the maximum quantum efficiency of photosystem II (PSII) (Fv/Fm), and the quantum efficiency of PSII (ΦPSII), but increased the intercellular CO2 concentration (Ci), suggesting that the decreased photosynthetic rate might be controlled by non-stomatal limitation (Table 1 and Figure 1b)
We found that low-P stress affects the expression of GmRCAβ gene
Summary
Crop growth and yield formation rely on photosynthesis, but the photosynthetic process largely relies on phosphorus (P) and P-containing compounds [1,2]. Efficient use of P is a potentially important determinant of plant photosynthesis, further benefiting crop growth and yield. As an important crop grown worldwide providing both protein meal and vegetable oil for consumption, soybean accounts for more than 50% of the global oilseed production [6]. Soybean is a high P demand species, and low-P stress is a key factor constraining soybean growth and yield [7]. It has been reported that more than 5.7 billion ha of land worldwide is deficient in plant-available P [9,10], resulting in the reduction of average global soybean production
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