Differential proteomic analysis of rice seedlings reveals the advantage of dry-raising nursery practices

Dry-raising rice seedlings in nurseries is a key technique in high-yield rice cultivation. The present study of morphological and physiological indexes showed dry-raised seedlings (DRS) had a shorter stature, more developed root systems, and significantly higher soluble sugar, starch, and N content than moist-raised seedlings (MRS), resulting in significantly increased grain yield. Compared to the MRS techniques, the dry-raised measures induced higher levels of abscisic acid (ABA), gibberellins (GA3), and indole-3-acetic acid (IAA) in leaves and roots of seedlings. We then utilized tandem mass tags (TMT) quantitative proteomics technology to analyze the mechanism by which rice exposed to the appropriate drought stress (dry-raised measures) during the seedling stage develop differently. Through mass spectrometry, we identified 281 significantly expressed proteins in roots and 268 in leaves. The differentially expressed proteins were then divided into 23 categories based on MapMan ontology. In addition, the hormonal-related protein expression patterns of DRS were confirmed with RT-PCR at the transcript level. On the basis of these findings, we proposed that appropriate drought stress during the rice seedling stage can change the expression of key proteins involved in nitrogen uptake and translocation, hormone synthesis, photosynthesis, and CHO metabolic processes, thus regulating rice seedling growth. In this process, the differentially expressed key proteins, such as the 14-3-3 protein, GTP-binding protein, and calcium, play important roles in transduction of signals regarding soil drought, and the upregulated heat shock protein, glutathione S-transferases, and peroxidases function in enhancing the stress tolerance of the seedlings under dry-raising nursery conditions. This study established the high yielding mechanism of dry-raised cultivates methods during seedling stage at the protein expression level.