When grafting or wounding disconnects stem tissues, new tissues are generated to restore the lost connection. In this study, the molecular mechanism of such healing was elucidated in injured stems of Arabidopsis. Soon after the inflorescence stems were incised, the pith cells started to divide. This process was strongly inhibited by the elimination of cauline leaves, shoot apices, or lateral buds that reduced the indole-3-acetic acid supply. Microarray and quantitative RT-PCR analyses revealed that genes related to cell division, phytohormones, and transcription factors were expressed because of incision. Among them, two plant-specific transcription factor genes, ANAC071 and RAP2.6L, were abundantly expressed. ANAC071 was expressed at 1-3 d after cutting exclusively in the upper region of the cut gap, with concomitant accumulation of indole-3-acetic acid. In contrast, RAP2.6L was expressed at 1 d after cutting exclusively in the lower region, with concomitant deprivation of indole-3-acetic acid. The expression of ANAC071 and RAP2.6L were also promoted by ethylene and jasmonic acid, respectively. In transformants suppressing the function of RAP2.6L or ANAC071, the division of pith cells was inhibited. Furthermore, the ethylene signaling-defective ein2 mutant showed incomplete healing. Hence, plant-specific transcription factors differentially expressed around the cut position were essential for tissue reunion of Arabidopsis wounded flowering stems and were under opposite control by polar-transported auxin, with modification by the ethylene and jasmonic acid wound-inducible hormones.regeneration | meristem | stress
Plant grafting is conducted for fruit and vegetable propagation, whereby a piece of living tissue is attached to another through cell-cell adhesion. However, graft compatibility limits combinations to closely related species, and the mechanism is poorly understood. We found that Nicotiana is capable of graft adhesion with a diverse range of angiosperms. Comparative transcriptomic analyses on graft combinations indicated that a subclade of β-1,4-glucanases secreted into the extracellular region facilitates cell wall reconstruction near the graft interface. Grafting was promoted by overexpression of the β-1,4-glucanase. Using Nicotiana stem as an interscion, we produced tomato fruits on rootstocks from other plant families. These findings demonstrate that the process of cell-cell adhesion is a potential target to enhance plant grafting techniques.
Cucumber (Cucumis sativus) hypocotyls were cut to one-half of their diameter transversely, and morphological and histochemical analyses of the process of tissue reunion in the cortex were performed. Cell division in the cortex commenced 3 d after cutting, and the cortex was nearly fully united within 7 d. 4Ј,6-Diamidino-2-phenylindole staining and 5-bromo-2Ј-deoxyuridine labeling experiments indicate that nDNA synthesis occurred during this process. In addition, specific accumulation of pectic substances was observed in the cell wall of attached cells in the reunion region of the cortex. Cell division during tissue reunion was strongly inhibited when the cotyledon was removed. This inhibition was reversed by applying gibberellin (GA, 10 Ϫ4 m GA 3 ) to the apical tip of the cotyledon-less plant. Supporting this observation, cell division in the cortex was inhibited by treatment of the cotyledon with 10 Ϫ4 m uniconazole-P (an inhibitor of GA biosynthesis), and this inhibition was also reversed by simultaneous application of GA. In contrast to the essential role of cotyledon, normal tissue reunion in cut hypocotyls was still observed when the shoot apex was removed. The requirement of GA for tissue reunion in cut hypocotyls was also evident in the GA-deficient gib-1 mutant of tomato (Lycopersicon esculentum). Our results suggest that GA, possibly produced in cotyledons, is essential for cell division in reuniting cortex of cut hypocotyls.Immediately following cell division in higher plants, the two daughter cells are attached to each other as a result of the formation of the cell plate. These cells then maintain cell-to-cell attachment or separate from each other. The phenomenon in which separated cells epigenetically re-adhere, as seen in animal systems, is not typically observed in plants, but does occur in certain processes such as carpel fusion during gynoecium development (Walker, 1975; Siegel and Verbeke, 1989; van der Schoot et al., 1995), tissue union during grafting (Kollmann and Glockmann, 1985; Richardson et al., 1996; Wang and Kollmann, 1996), and cell repair in cut tissues. In Arabidopsis, mutants with ectopic fusion or adhesion of aerial tissues have been identified, including fiddlehead (Lolle et al., 1992(Lolle et al., , 1997 Lolle and Cheung, 1993; Lolle and Pruitt, 1999) and wax-1 (Jenks et al., 1996).Studies on graft union and repair in cut tissues have focused on the differentiation of vascular elements in the tissue reunion process because the formation of the vascular bundle is a useful model system for studying cell differentiation and organization in higher plants (Stoddard and McCully, 1980; Moore and Walker, 1981; Kollmann and Glockmann, 1985; Monzer and Kollmann, 1986; Roberts, 1988; Tiedemann, 1989; Sachs, 2000). Although the molecular mechanisms controlling vascular differentiation are not yet fully understood, the involvement of phytohormones such as auxin and cytokinin in xylem and phloem differentiation has been suggested (Roberts, 1988; Mattsson et al., 1999; Sachs, 2000)...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.