Abstract: 【Objective】 The objectives of this research are to analyze the structural features, patterns of expression and drought tolerance functions of natriuretic peptide gene GhPNP1 in cotton, and provide a theoretical basis for future deeper study of crop drought tolerance. 【Method】 The homolog protein sequences of plant natriuretic peptides in cotton were obtained by a BLASTP search in Gossypium raimondii protein database using the query protein sequence of Verticillium dahliae plant natriuretic peptides gene Ave1 acquired from plants through horizontal gene transfer. Homologous analysis and multiple alignments were performed with MEGA 5. Expasy online tools were used for protein sequence analysis. The GhPNP1 was amplified in Gossypium hirsutum Ao3503 using the primers that were designed according to the nucleotide acid sequence of the homolog protein sequence. The isoelectric point, molecular weight, signal peptide and phylogenetic tree of the encoding protein were analyzed by related bioinformatics programs. The expression analysis of GhPNP1 gene in different organs and by PEG simulating drought stress treatment was conducted by real-time PCR. The virus induced gene silence vector was constructed and the GhPNP1 silenced cotton plants were obtained. The cDNA sequences of GhPNP1 was add to CLCrV silencing vector to construct virus-induced gene silencing vector CLCrV: GhPNP1 of GhPNP1. At 2-leaf-stage, cotton plant was infected and leaf tissues were obtained from hormone treated plant. PEG simulating drought stress treatment was used to determine the drought tolerance of GhPNP1 silenced cotton plants and test the several physiological indexes related to stress tolerance, such as water loss rate, relative water content, MDA content, T-AOC level and electrolyte leakage in GhPNP1 silenced cotton plants. 【Result】 GhPNP1 obtained in Gossypium hirsutum Ao3503 has an ORF with 396 nucleotides and encodes a protein of 131 amino acids, its isoelectric point is 9.13, the predicted molecular weight is 14.6 kD and with a signal peptide of 15 amino acids. The protein contained a conserved natriuretic peptides domain and with the highest similarity of GhPNP1 in Theobroma cacao. Quantitative real-time PCR (qRT-PCR) was used to examine the expression pattern of GhPNP1 in drought stress treatment. GhPNP1 exhibited weakly organ different expressed pattern with a little stronger expressed in stem, and moderately expressed in cotton root and leaves. In addition, PEG simulating drought stress treatment induced the up-regulated expression of GhPNP1 significantly in all the organs. The drought tolerance of GhPNP1 silenced cotton plants decreased significantly. The MDA content, electrolyte leakage and water loss rate of GhPNP1 silenced cotton plants were significantly higher than un-silenced cotton plants, wherever the T-AOC level and relative water content of silenced cotton plants were significantly lower than the un-silenced cotton plants. 【Conclusion】A plant natriuretic peptides gene (GhPNP1) was cloned from cotton, which is induced up-regulated by PEG simulating drought stress treatment and GhPNP1 silenced cotton plants significantly decreased drought tolerance. These imply that GhPNP1 may affect the drought tolerance of cotton through a cGMP dependent regulation pathway. GhPNP1 may play a positive role in drought tolerance of cotton.

Key words: upland cotton, virus induced gene silence, drought stress, function analysis