Phosphoproteomic analyses the tetraploid Citrus wilsonii enhanced drought tolerance

In this study, 17 plants of tetraploid “Zhique” were firstly identified by screening 570 natural seedlings of Citrus wilsonii Tanaka. These tetraploid plants showed different morphology and exhibited significantly increased drought tolerance than the diploids via determination of leaf water potential, relative water content and electrolyte leakage. Large number of genes involved in photosynthesis-responsive were differentially expressed in tetraploids under drought stress by global transcriptome analysis, which was consistent with the detection of photosynthesis indicator including photosynthetic rate, stomatal conductance, chlorophyll and so on. Compared with diploids, phosphorylation modification also plays an important role in the tetraploids after drought stress through the transcriptional and protein level analysis. Additionally, the genes involved in the phenylpropanoid biosynthesis and starch and sucrose metabolism pathways were enriched in both tetraploids and diploids in response to water deficient. Importantly, tetraploids significantly take priority over the diploid via regulating plant hormone signal transduction, especially improving the levels of 3-indoleacetic acid, abscisic acid and salicylic acid and reducing gibberellic A3 and jasmonic acid contents. Collectively, our data reveals that synergistic regulation photosynthesis, phosphorylation modification and plant hormones accumulation contribute to drought tolerance of autotetraploid in Citrus wilsonii.