Nitrogen (N), phosphorus (P), and potassium (K) are essential macronutrients that are crucial not only for maize growth and development, but also for crop yield and quality.  The genetic basis of macronutrient dynamics and accumulation during grain filling in maize remains largely unknown.  In this study, we evaluated grain N, P, and K concentrations in 206 recombinant inbred lines generated from a cross of DH1M and T877 at six time points after pollination.  We then calculated conditional phenotypic values at different time intervals to explore the dynamic characteristics of the N, P, and K concentrations.  Abundant phenotypic variations were observed in the concentrations and net changes of these nutrients.  Unconditional quantitative trait locus (QTL) mapping revealed 41 non-redundant QTLs, including 17, 16, and 14 for the N, P, and K concentrations, respectively.  Conditional QTL mapping uncovered 39 non-redundant QTLs related to net changes in the N, P, and K concentrations.  By combining QTL, gene expression, co-expression analysis, and comparative genomic data, we identified 44, 36, and 44 candidate genes for the N, P, and K concentrations, respectively, including GRMZM2G371058 encoding a Dof-type zinc finger DNA-binding family protein, which was associated with the N concentration, and GRMZM2G113967 encoding a CBL-interacting protein kinase, which was related to the K concentration.  The results deepen our understanding of the genetic factors controlling N, P, and K accumulation during maize grain development and provide valuable genes for the genetic improvement of nutrient concentrations in maize.

Rosa sterilis S. D. Shi is an important economic tree in China that produces fruits with high nutritional and medicinal value.  Many of R. sterilis’ organs are covered with different types of trichomes or prickles that directly affect fruit appearance and plant management.  This study used RNA sequencing technology to analyze the transcriptomes of two parts of the inflorescence branch, namely inflorescence stems with flagellated trichomes and pedicels with both flagellated and glandular trichomes.  Comparative transcriptomic analysis showed that many transcription factors (TFs) are potentially involved in the formation and development of trichomes.  The accumulation of RsETC1, a TF of the R3-MYB family, was significantly higher in inflorescence stems than in pedicels; quantitative reverse transcription PCR (qRT-PCR) verified that its expression was significantly higher in inflorescence stems than in pedicels during the first three development stages, indicating its inhibitory action on the initiation of glandular trichomes in R. sterilis.  The mRNA level of RsETC1 accumulated to significantly higher levels in trichomeless tissues than in tissues with trichromes, suggesting that this gene may inhibit the formation of trichomes in R. sterilis.  Over-expression of RsETC1 in Arabidopsis resulted in glabrous phenotypes, and the expression of trichome-related endogenous genes, except for TTG1, was markedly reduced.  In addition, the contents of the phytohormones jasmonic acid (JA), gibberellin A3 (GA₃), and cytokinins (CKs) in pedicels were significantly higher than those in inflorescence stems, and the expression patterns of the genes related to hormone biosynthesis and signal transduction presented consistent responses, suggesting that the transduction of these hormones might be crucial for trichome initiation and development.  These data provide a new perspective for revealing the molecular mechanism of trichome formation in R. sterilis.