Analysis Of Potassium Transport Family In Upland Cotton And Functional Analysis Of GhPOT8 In The Secondary Cell Wall Synthetics

Potassium is one of the three essential nutrients for plant growth and development.It exists in the form of ions in plant cells and participates in a variety of biological processes,such as maintaining intracellular PH,cell elongation,enzyme activation,osmotic adjustment,etc.Cotton is a potassium-loving crop and requires a lot of potassium during its growth.Increased application of potassium fertilizer can promote the elongation of cotton main roots and the occurrence of lateral roots,enhance the resistance of cotton,and improve the quality of cotton fiber.In vitro culture found that lack of potassium can seriously affect the development of fiber cells.Multiple studies have shown that potassium plays an indispensable role in the formation and development of cotton fibers.In the previous research of our laboratory,a major QTL related to fiber strength was obtained.In the QTL,there is a gene GhPOT8,which is highly expressed in the secondary wall thickening period.This gene encodes a potassium transporter(potassium transporter).In order to understand the specific function of this gene in cotton,we analyzed the potassium transport family of GhPOT8 and the biological function of GhPOT8.The results are as follows:1.According to the protein sequence characteristics of GhPOT8,21,24,45 and44 HAK/KUP/KT members were identified in Gossypium.arboreum,Gossypium.raimondii,Gossypium.hirsutum,Gossypium.barbadense using a variety of comparison methods.Analysis of gene structure,motifs and conserved domains revealed that the genes in the HAK/KUP/KT family are highly conserved among various cotton species.Transcriptome data and q RT-PCR analysis indicate that some HAK/KUP/KT family genes in upland cotton are predominantly expressed at different stages of fiber development and may be involved in cotton fiber development.Salt and drought stress show that some HAK/KUP/KT genes respond to stress and may be involved in the resistance of cotton.2.Analysis of tissue expression specificity found that GhPOT8 was predominantly expressed during the secondary wall thickening period,indicating that it may participate in the secondary wall thickening period of fiber cells,then affect the strength of the fiber.The subcellular localization results showed that GhPOT8 was located on the cell membrane;the promoter segmentation results showed that the light response and stress response elements located at-927～-997 bp have transcription activity.3.Compared with WT Arabidopsis,GhPOT8 transgenic Arabidopsis overexpression lines showed more thicken in the leaf cell walls and stem xylem;in addition,GhPOT8 overexpression Arabidopsis had significantly more lateral root development than the control.It shows that GhPOT8 may also be involved in the occurrence of lateral roots.Virus Induced Gene Silencing(VIGS)experiments found that the fiber strength of GhPOT8-silenced cotton plants was lower than CK,indicating that GhPOT8 is involved in the secondary wall thickening process of cotton fiber development.