Minkai Yang

(R)-Shikonin/(S)-Alkannin and their derivatives (collectively denoted as shikonin) are abundantly distributed in the roots of Boraginaceae plants. Acetylshikonin, as a crucial derivative of (R)-shikonin, possesses substantial research significance. Previous investigations have shown that LeSAT2, specifically catalyzes the acylation of (R)-shikonin to yield various acylated (R)-shikonin derivatives, including acetylshikonin. Additionally, electrophoretic mobility shift assays (EMSA) indicated that LeWRKY24 transcription factors may participate in the transcriptional regulation of LeSAT2. In this study, the interaction between LeWRKY24 and LeSAT2 was further verified using yeast one-hybrid and dual-luciferase assays. The LeWRKY24 overexpression vector was constructed and introduced into Echium plantagineum to induce transgenic hairy roots. High-performance liquid chromatography (HPLC) analysis showed that in LeWRKY24-overexpressing hairy root lines, the total pigment content was significantly increased, and in particular, the content of acetylshikonin was specifically upregulated by as much as 200‐fold. Transcriptome data revealed that genes associated with shikonin biosynthesis in the overexpression lines were significantly upregulated, activating the metabolic pathway, which explains the molecular mechanism underlying this regulatory effect. Our results also confirm that LeWRKY24 possesses cross-species regulatory universality in shikonin biosynthesis, laying a foundation for its widespread application in the metabolic engineering of Boraginaceae plants.

Phosphate (Pi) is an essential nutrient that frequently limits plant growth because of its low availability in soils, especially during early seedling development in Arabidopsis . Under Pi-deficient conditions, etiolated seedlings exhibit elongated hypocotyls, shortened roots, and small, pale cotyledons—a morphological adaptation that enhances light-foraging capacity. However, how Pi is strategically distributed among these organs to optimize seedling establishment remains unclear. We here identify a PHR1-EIN3/EIL1 regulatory module that directs minimal Pi resources to suppress root elongation and cotyledon expansion or to accelerate greening, promoting Pi conservation. This mechanism prioritizes hypocotyl elongation to improve light acquisition. In contrast, under sufficient Pi supply, hypocotyl and root growth is promoted along with cotyledon enlargement, while greening is delayed. Thus, the PHR1-EIN3/EIL1 module enables efficient allocation of limited Pi to maximize hypocotyl elongation for light foraging during early seedling establishment while strategically restricting Pi usage in other organs to enhance overall survival.

Transgenic technology has been widely applied to crop development, with genetically modified (GM) maize being the world’s second-largest GM crop. Despite the fact that rhizosphere bacterial and fungal populations are critical regulators of plant performance, few studies have evaluated the influence of GM maize on these communities. Plant materials used in this study included the control maize line B73 and themcry1Abandmcry2Abdual transgenic insect-resistant maize line 2A-7. The plants and soils samples were sampled at three growth stages (jointing, flowering, and maturing stages), and the sampling compartments from the outside to the inside of the root are surrounding soil (SS), rhizospheric soil (RS), and intact root (RT), respectively. In this study, the results of alpha diversity revealed that from the outside to the inside of the root, the community richness and diversity declined while community coverage increased. Morever, the different host niches of maize rhizosphere and maize development stages influenced beta diversity according to statistical analysis. The GM maize line 2A-7 had no significant influence on the composition of microbial communities when compared to B73. Compared to RS and SS, the host niche RT tended to deplete Chloroflexi, Gemmatimonadetes and Mortierellomycota at phylum level. Nitrogen-fixation bacteriaPseudomonas,Herbaspirillum huttiense,Rhizobium leguminosarum, andSphingomonas azotifigenswere found to be enriched in the niche RT in comparison to RS and SS, whilstBacilluswas found to be increased andStenotrophomonaswas found to be decreased at the maturing stage as compared to jointing and flowering stages. The nitrogen fixation protein FixH (clusters of orthologous groups, COG5456), was found to be abundant in RT. Furthermore, the pathogen fungus that causes maize stalk rot,Gaeumannomyces radicicola, was found to be abundant in RT, while the beneficial fungusMortierella hyalinawas found to be depleted in RT. Lastly, the abundance ofG. radicicolagradually increased during the development of maize. In conclusion, the host niches throughout the soil-plant continuum rather than the Bt insect-resistant gene or Bt protein secretion were primarily responsible for the differential assembly of root-associated microbial communities in GM maize, which provides the theoretical basis for ecological agriculture.

MicroRNAs (miRNAs) play an important role in plant growth, development, and response to environment. For identifying and comparing miRNAs and their targets in seed development between two maize inbred lines (i.e. PH6WC and PH4CV), two sRNAs and two degradome libraries were constructed. Through high-throughput sequencing and miRNA identification, 55 conserved and 24 novel unique miRNA sequences were identified in two sRNA libraries; moreover, through degradome sequencing and analysis, 137 target transcripts corresponding to 38 unique miRNA sequences were identified in two degradome libraries. Subsequently, 16 significantly differentially expressed miRNA sequences were verified by qRT-PCR, in which 9 verified sequences obviously target 30 transcripts mainly involved with regulation in flowering and development in embryo. Therefore, the results suggested that some miRNAs (e.g. miR156, miR171, miR396 and miR444) related reproductive development might differentially express in seed development between the PH6WC and PH4CV maize inbred lines in this present study.