Pengjie Chang

In vitro regeneration of plants from tissues such as leaf or root explants typically starts with auxin-induced formation of a pluripotent cell mass termed callus. This cellular reprogramming is essential for the subsequent regeneration of shoots or roots. However, whether or how lipid metabolism is involved in callus formation and thus plant regeneration remains largely unclear. Here, we report that phospholipid remodeling is critical for auxin-induced callus formation during the regeneration of Arabidopsis thaliana. We show that phospholipid metabolism changes dynamically during auxin-induced pluripotent callus formation, and that interfering with the phospholipid metabolic pathway enhances or dampens callus formation induced by auxin. We further demonstrate that the phospholipid metabolite phosphatidic acid (PA) inhibits callus formation by binding to auxin signaling repressors of the INDOLE-3-ACETIC ACID INDUCIBLE (IAA) family and enhancing their stability, thereby decreasing auxin signaling and the callus-forming program. Our findings reveal the molecular interplay between phospholipid metabolism and auxin signaling during plant regeneration and identify developmental programs that may participate in this process.

Phospholipids function as dynamic regulators of plant growth and environmental adaptation, extending well beyond their structural roles in biological membranes. This review synthesizes the phospholipid metabolic network and its regulatory functions in plant physiology. We first describe enzymatic reactions and acyl-chain remodeling in phospholipid biosynthesis, and then examine the interaction between phospholipid metabolism and auxin signaling, focusing on phosphatidic acid (PA) and phosphoinositide phosphate (PIP). These lipid molecules regulate the polarization and vesicular trafficking of PIN-FORMED proteins via endocytosis and phosphorylation-dependent mechanisms, thereby controlling auxin distribution during development and stress adaptation. Particular emphasis is placed on PA, a multifunctional signaling lipid that serves as a central molecular hub. PA coordinates hormonal, stress, and circadian signals by engaging and modulating a broad spectrum of protein targets, including kinases, phosphatases, and transcription factors. We also discuss the emerging and evolutionarily conserved functions of phospholipid signaling in cell fate determination, drawing parallels from mammalian cell reprogramming to the regulation of plant cell totipotency and root patterning. Collectively, these findings underscore the critical role of phospholipid-mediated signaling in converting metabolic and environmental cues into developmental reprogramming, providing novel theoretical and functional frameworks for future research in plant lipid biology.

Floral organ development plays a critical role in determining crop yield and quality, yet the molecular mechanisms underlying this process in sesame remain poorly understood. In this study, comparative transcriptomic analyses were conducted between the wild-type Yuzhi11 and a dehiscent-corolla mutant, css1, to investigate the genetic basis of floral organ variation. A total of 114 differentially expressed genes (DEGs) were identified between the two genotypes in both the main and lateral flowers, among which 47 candidate genes were implicated in main/lateral floral organ development. A weighted gene co-expression network analysis (WGCNA) revealed two gene modules significantly associated with the mutant’s main and lateral flowers, respectively. Five hub genes were identified within each module, and their potential regulatory networks and protein–protein interactions networks were characterized. These findings provide new insights into the genetic regulation of flower and fruit development in sesame, and may inform future breeding strategies to optimize floral and yield related traits.

Induction of the pluripotent cell mass termed callus from detached organs or tissues is an initial step in typical in vitro plant regeneration, during which auxin-induced ectopic activation of root stem cell factors are required for subsequent de novo shoot regeneration. While Arabidopsis (Arabidopsis thaliana) AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19 and their downstream transcription factors LATERAL ORGAN BOUNDARIES DOMAIN (LBD) are known to play key roles in directing callus formation, the molecules responsible for activation of root stem cell factors and thus establishment of callus pluripotency are unclear. Here, we identified Arabidopsis WRKY23 and BASIC HELIX-LOOP-HELIX 041 (bHLH041) as a transcriptional activator and repressor, respectively, of root stem cell factors during establishment of auxin-induced callus pluripotency. We show that auxin-induced WRKY23 downstream of ARF7 and ARF19 directly activates the transcription of PLETHORA 3 (PLT3) and PLT7 and thus that of the downstream genes PLT1, PLT2 and WUSCHEL-RELATED HOMEOBOX 5 (WOX5), while LBD-induced removal of bHLH041 derepresses the transcription of PLT1, PLT2 and WOX5. We provide evidence that transcriptional activation by WRKY23 and loss of bHLH041-imposed repression act synergistically in conferring shoot-regenerating capability on callus cells. Our findings thus disclose a transcriptional mechanism underlying auxin-induced cellular reprogramming, which, together with previous studies, outlines the molecular framework of auxin-induced pluripotent callus formation for in vitro plant regeneration programs.