Molecular Characterization of Auxin Efflux Carrier- ABCB1 in hexaploid wheat

Characterization of the PIN Auxin Efflux Carrier Gene Family and Its Expression during Zygotic Embryogenesis in Persea americana

Auxins are responsible for a large part of the plant development process. To exert their action, they must move throughout the plant and from cell to cell, which is why plants have developed complex transport systems for indole-3-acetic acid (IAA). These transporters involve proteins that transport IAA into cells, transporters that move IAA to or from different organelles, mainly the endoplasmic reticulum, and transporters that move IAA out of the cell. This research determined that Persea americana has 12 PIN transporters in its genome. The twelve transporters are expressed during different stages of development in P. americana zygotic embryos. Using different bioinformatics tools, we determined the type of transporter of each of the P. americana PIN proteins and their structure and possible location in the cell. We also predict the potential phosphorylation sites for each of the twelve-PIN proteins. The data show the presence of highly conserved sites for phosphorylation and those sites involved in the interaction with the IAA.

A mutation in CsABCB19 encoding an ATP-binding cassette auxin transporter leads to erect and compact leaf architecture in cucumber (Cucumis sativus L.)

Leaf architecture, including leaf position and leaf morphology, is a critical component of plant architecture that directly determines plant appearance, photosynthetic utilization, and ultimate productivity. The mechanisms regulating leaf petiole angle and leaf flatness in cucumber remain unclear. In this study, we identified an erect and compact leaf architecture mutant (ecla) from an EMS (ethyl methanesulfonate) -mutagenized cucumber population, which exhibited erect petioles and crinkled leaves. Histological examination revealed significant phenotypic variation in ecla was associated with asymmetric cell expansion. MutMap sequencing combined with genetic mapping revealed that CsaV3_5G037960 is the causative gene for the ecla mutant phenotype. Through protein sequence alignment and Arabidopsis genetic complementation, we identified this gene as a functional direct homolog encoding the ATP-binding cassette transporter AtABCB19, hence named CsABCB19. A nonsynonymous mutation in the eleventh exon of CsABCB19 leads to premature termination of translation. The expression level of CsABCB19 in the ecla mutant was significantly reduced in all tissues compared to the wild type (WT). Transcriptome analysis revealed that auxin and polarity-related genes were significantly differentially expressed in mutant petioles and leaves, compared with those in WT. Auxin assay and exogenous treatment further demonstrated that CsABCB19 regulates leaf architecture by mediating auxin accumulation and transport. Our research is the first report describing the role of the ABCB19 transporter protein in auxin transport controlling cucumber leaf development. Furthermore, this study provides recent insights into the genetic mechanisms conferring morphological diversity and regulation of petiole angle and leaf flattening. DATA AVAILABILITY: The RNA-seq data in this study have been deposited in the NCBI SRA under BioProject accession number PRJNA874548.

Genome-wide identification and expression profiles of ABCB gene family in Chinese hickory (Carya cathayensis Sarg.) during grafting

Chinese hickory (Carya cathayensis Sarg.) is an important nut tree species native to China. Excessive plant height and long juvenile phase has restricted development of its industry. Recently, grafting has been used increasingly in production practice of this species to solve the problems above. Previous studies have proved the importance of auxin during Chinese hickory grafting. However, the function of ATP-binding cassette subfamily B (ABCB) genes during Chinese hickory grafting is less studied. In this study, 23 ABCB genes were identified and characterized in Chinese hickory (CcABCBs). The expression profiles of auxin-related ABCBs among tissues, under auxin-related phytohormone treatments and during grafting were determined. CcABCB proteins were divided into half-size and full-size transporters. Many phytohormone-related cis-acting regulatory elements were detected on the promoters of CcABCB genes. Four CcABCB genes homologous to auxin-related AtABCB1, 6, 19 and 20 in Arabidopsis were selected for expression analysis. The four genes displayed varying expression patterns in different tissues of Chinese hickory. Expressions of the four CcABCB genes were regulated by auxin-related phytohormones to varying degrees. Expression levels of the four genes were significantly changed at different stages of grafting, especially 7 days after grafting, indicating their involvement of auxin homeostasis regulation during grafting. In addition, the expressions of CcABCB1 were regulated by IAA and NPA treatments during grafting in comparison with CK treatment, while expressions of the other 3 CcABCB genes were slightly affected. This study will lay the foundation for understanding the potential regulatory roles of CcABCB genes during Chinese hickory grafting.