| N-(2-chloro-4-pyridyl)-N.-phenylurea(CPPU)is an important type of cytokinin plant growth regulator,which has a good regulatory effect on the expansion of fruits and root crops.In order to explore the application method of chlorfenuron in promoting the expansion of sweet potato roots and explore the molecular mechanism of CPPU’s role in regulating the development and growth of sweet potato,this study used sweet potato Jishu 26 as the test material,and sprayed at the initial stage of tuber expansion.Foliar sprays of different concentrations of chlorfenuron were carried out to study the effects of CPPU on the photosynthetic physiological indexes of sweet potato,the growth of sweet potato vines,the yield of sweet potato roots and agronomic characteristics.The endogenous hormone content in the shoot tips and young roots of sweet potato treated with CPPU was determined,and the differentially expressed genes were analyzed by transcriptome sequencing.1.In the early stage of sweet potato tuber swelling,four concentrations of CPPU foliar spray treatment were carried out,among which spraying concentrations of 6mg/L and 9 mg/L could increase leaf chlorophyll content,stomatal conductance and transpiration rate,thereby increasing Net photosynthetic rate,and 3 mg/L and 12mg/L treatments had little effect on various photosynthetic indexes.2.Low concentration(3 mg/L,6 mg/L)CPPU treatment makes sweet potato vine length and internode lengthen,while high concentration(9 mg/L,12 mg/L)CPPU treatment makes sweet potato vine length and internode length shorter,Different treatments can increase the yield of above-ground part.3.The appropriate concentration of CPPU can increase the yield of sweet potatoes.The 9 mg/L treatment has the best effect.The total yield and the yield of commercial potatoes are increased by 7.61% and 11.84% respectively compared with the control.The increase in the yield of large potatoes is particularly significant,reaching 24.45%,indicating that CPPU It can promote the expansion of tuber roots.At the same time,this concentration treatment significantly increases the dry rate of sweet potato tubers and the soluble sugar content.4.Using high-concentration CPPU for foliar spraying,the endogenous hormone content of shoot tips and young roots were detected respectively.The gibberellins,auxin and abscisic acid of shoot tips and young roots all showed a downward trend.The cytokinin hormones showed an upward trend.Among them,only N6-(Δ2-isopentenyl)adenosine increased significantly in the shoot tip.In addition to the significant increase of N6-(Δ2-isopentenyl)adenosine in young roots,it was reversed.The content of zeatin nucleoside and aminocyclopropane carboxylic acid both increased significantly.The salicylic acid content is also inconsistent in the realization of shoot tips and young roots,the shoot tip content increased significantly,but the young roots changed little.5.Transcriptome sequencing analysis results showed that there were 146 differentially expressed genes in the shoot tip,129 up-regulated genes,17down-regulated genes,1744 differently expressed genes in young roots,1100up-regulated genes,and 644 down-regulated genes.After the KEGG pathway analysis,39 signal pathways were enriched in the stem tip,among which the differentially expressed genes involved the zeatin synthesis pathway and the plant hormone signal transduction pathway,and the tuber roots had 89 signal pathways enriched,of which the plant hormones were differentially expressed Signal transduction pathway and phenylpropane biosynthesis pathway.Comprehensive endogenous hormone determination results indicate that CPPU mainly regulates the growth and development of sweet potato by promoting the synthesis of zeatin.This thesis provides a theoretical basis for the application of CPPU in sweet potato and other rhizome crops,and at the same time opens the way for the study of the molecular mechanism of CPPU regulating the growth and development of rhizome crops. |
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