Abstract
Plants, unlike animals, have developed a unique system in which they continue to form organs throughout their entire life cycle, even after embryonic development. This is possible because plants possess a small group of pluripotent stem cells in their meristems. The shoot apical meristem (SAM) plays a key role in forming all of the aerial structures of plants, including floral meristems (FMs). The FMs subsequently give rise to the floral organs containing reproductive structures. Studies in the past few decades have revealed the importance of transcription factors and secreted peptides in meristem activity using the model plant Arabidopsis thaliana. Recent advances in genomic, transcriptomic, imaging, and modeling technologies have allowed us to explore the interplay between transcription factors, secreted peptides, and plant hormones. Two different classes of plant hormones, cytokinins and auxins, and their interaction are particularly important for controlling SAM and FM development. This review focuses on the current issues surrounding the crosstalk between the hormonal and genetic regulatory network during meristem self-renewal and organogenesis.
Highlights
Throughout their entire life cycle, plants possess a small group of pluripotent stem cells in their meristems [1,2,3]
The shoot apical meristem (SAM) harbors a set of stem cells within the central zone (CZ) surrounded by the peripheral zone (PZ) (Figure 1c)
Cells located in the CZ divide slowly, while cells located in the PZ divide rapidly (Figure 1c)
Summary
Throughout their entire life cycle, plants possess a small group of pluripotent stem cells in their meristems [1,2,3]. WUS, which is expressed in the OC, controls biological processes through the transcriptional regulation of downstream target genes related to meristem growth, cell division, and hormonal signaling [19,20,21,22]. The negative feedback loop between stem cells and the OC mediated by these two proteins ensures stem cell homeostasis in the SAM and indefinite organ formation (Figure 1d). The balance between the rates of stem cell proliferation and differentiation in the FM is pivotal for the proper formation of flower organs, such as sepals, petals, stamens, and carpels (Figure 1d) [36]. The precise control of the termination of the FM by multiple factors ensures stem cell homeostasis in the FM and the formation of determinate floral organs. AAfflloowweerr ccoonnssiissttss ooffffoouurrsseeppaallss,,ssiixxssttaammeennss,,ffoouurrppeettaallss,,aannddttwwooccaarrppeellss..AAfflloowweerrffrroommaa3300--ddaayy--ooldldpplalannttisissshhoowwnn. . ((ee)) TToopp vviieeww ooff tthheeFFMMaattsstataggee33. .SSccaalelebbaarr==2200μμmm. .(f(f))TTooppvvieiwewofotfhteheFMFMatasttastgaeg6e. 6O. rOgragnaiznaiztiaotnioonf othf ethFeMFMshoswhoinwginfugnfcutniocntiaolnzaolnzeosnaensdancedllclealyl elrasy.eTrsh.eTOhCe ,OwCh,iwchheicxhhiebxithsibwitesakwWeaUk SWeUxpSreesxspiroenssoinolny oant lsytaagtest3aagned eaanrdlyesatralgyest6a,gise s6h, oiswsnhoinwpninink.pSincakl.eSbcaalre=ba2r0 =μm20. μm
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