Effects Of Different Phosphorus Levels On Root Morphology And Phosphorus Uptake Gene Expression Of Two Genotypes Of Cotton

In order to improve the utilization efficiency of phosphorus in cotton,the physiological molecular mechanism of efficient absorption and transport of phosphorus in cotton was analyzed.In this study,the high phosphorus efficiency cotton XLZ19 and low phosphorus efficiency cotton XLZ13,which were screened in the early stage of the research group,were used as the research objects to compare the phosphorus accumulation and root morphology of the two genotypes of cotton,and the root phosphorus absorption was compared.The CDS sequences of the genes were subjected to phylogenetic and bioinformatics analysis,and fluorescence quantitative PCR was used to analyze the differences in the expression of phosphorus uptake genes in roots.The main conclusions of this study are as follows:1.The growth of cotton of different genotypes is affected by the level of phosphorus supply.Over time,the biomass of each organ of XLZ19 was higher than that of XLZ13 at different phosphorus levels;with the increase of phosphorus level,XLZ19 could absorb and accumulate more phosphorus and form more biomass;XLZ19 had the highest phosphorus transfer coefficient,showing stronger low phosphorus tolerance characteristics,which proves that the high phosphorus efficiency genotype cotton has a stronger ability to absorb soil available phosphorus than the low phosphorus efficiency genotype cotton.2.The root morphology of cotton of different genotypes is affected by the level of phosphorus supply.With the passage of time,the root morphological parameters of the two genotypes of cotton increased gradually;under different phosphorus treatments,XLZ19 showed growth advantages in the late growth stage,and its total root length and total root surface area were generally higher than those of XLZ13 under low phosphorus and normal phosphorus treatments.The average root diameter of XLZ19 was lower than that of XLZ13 in each period;with the passage of time,the root lengths of the three diameter ranges gradually increased,and the proportions showed as fine roots(0-0.5 mm)> medium roots(0.5-1.5 mm)> thick roots(>1.5 mm);the root length and root surface area of XLZ19 in the late growth stage were generally higher than those of XLZ13 under low-phosphorus and normal-phosphorus treatments;It has the characteristics of more total length,so XLZ19 can show a better ability to absorb phosphorus at the optimal phosphorus level.3.After bioinformatics analysis and phylogenetic analysis,it was found that Gossypium hirsutum inorganic phosphate transporter Gh Pht1 s gene are basically consistent with other plant Pht1 gene families in terms of protein physicochemical properties,protein hydrophobicity,conserved domains,and transmembrane domains.The Gh Pht1 s gene is in a phylogenetic tree.On the large branch of Malvaceae,it is most closely related to Gossypium raimondii and Gossypium arboreum,and also has a certain genetic relationship with the Brassicaceae Arabidopsis thaliana,the Leguminosae Glycine max and the Poaceae Oryza sativa and Herrania umbratica.4.The expression of Gh Pht1 s gene in roots of different genotypes of cotton was affected by the level of phosphorus supply.Over time,the expression pattern of the five genes showed that the flowering stage>the seedling stage;Gh Pht1-5,Gh Pht1-6,Gh Pht1-7,Gh Pht1-15,Gh Pht1-16 under the low phosphorus treatment(P0-P3)and the normal phosphorus treatment(P4-P5)Gh Pht1-15 and Gh Pht1-16 were induced to enhance expression;under low phosphorus treatment(P0-P3),the relative expression of Gh Pht1 s gene in XLZ19 at seedling stage was 1.07-2.94 times that of XLZ13,and the relative expression level of Gh Pht1 s gene in XLZ19 at flowering stage was 1.24-3.24 times that of XLZ13,which may have contributed mainly to the phosphorus-efficient phenotype of XLZ19.