Comparative physiological and proteomic analysis reveals different responding mechanisms of phosphate deficiency between two clones of Pinus elliottii x P. caribaea

Enhancing efficiency of phosphorus uptake and utilization in forest trees through genetic improvement is crucial for ecological conservation and climate change mitigation. Pinus species exhibit significant genetic variation in phosphorus efficiency (PE). However, potential regulation mechanisms of hybrid pine (Pinus elliottii x P. caribaea) under phosphate deficiency are still unclear. Two distinct hybrid pine genotypes, clone 38 and clone 31, were screened out from 28 hybrid pine genotypes based on morphological and physiological changes. Clone 38 showed superior heights and diameters under -Pi condition than +Pi condition, while Clone 31 showed a slight advantage under +Pi condition than -Pi condition. Root-shoot fresh weight (FW) and dry weight (DW) ratios in clone 38 under Pi (inorganic phosphate) deficiency increased more than that in clone 31. Clone 38 and clone 31 could be classified as the genotypes with high and low Pi efficient, respectively. In order to explore the mechanisms that hybrid pine employed to response to phosphate starvation, iTRAQ-based quantitative proteomics analysis of shoots of two clones (clone 31 and clone 38) was conducted. There were 94 and 106 proteins showed differential accumulation patterns under Pi deficient condition in clone 38 and clone 31, respectively. Pi deficit in shoots of high Pi efficient clone 38 resulted in the induction of proteins associated with amylopectin, sulfolipid, and sucrose metabolism. Inversely, proteins associated with photosynthesis were decreased in shoots of low Pi efficient clone 31. The proteins that are accumulated differently amongst genotypes with varying Pi efficiency provide a potential and foundation for developing hybrid pine genotypes with higher phosphate efficiency.