RESUMEN
Petal size is determined by cell division and cell expansion. Jasmonic acid (JA) has been reported to be associated with floral development, but its regulatory mechanism affecting petal size remains unclear. Here, we reveal the vital role of JA in regulating petal size and the duration of the cell division phase via the key JA signaling component RhMYC2. We show that RhMYC2 expression is induced by exogenous treatment with methyl jasmonate and decreases from stage 0 to stage 2 of flower organ development, corresponding to the cell division phase. Furthermore, silencing RhMYC2 shortened the duration of the cell division phase, ultimately accelerating flowering opening and resulting in smaller petals. In addition, we determined that RhMYC2 controls cytokinin homeostasis in rose petals by directly activating the expression of the cytokinin biosynthetic gene LONELY GUY3 (RhLOG3) and repressing that of the cytokinin catabolism gene CYTOKININ OXIDASE/DEHYDROGENASE6 (RhCKX6). Silencing RhLOG3 shortened the duration of the cell division period and produced smaller petals, similar to RhMYC2 silencing. Our results underscore the synergistic effects of JA and cytokinin in regulating floral development, especially for petal size in roses.
RESUMEN
Petal size, a crucial trait in the economically important ornamental rose (Rosa hybrida), is synergistically regulated by cell division and cell expansion. Cell division primarily occurs during the early development of petals. However, the molecular mechanism underlying the regulation of petal size is far from clear. In this study, we isolated the transcription factor gene RhSCL28, which is highly expressed at the early stage of rose petal development and is induced by cytokinin. Silencing RhSCL28 resulted in a reduced final petal size and reduced cell number in rose petals. Further analysis showed that RhSCL28 participates in the regulation of cell division by positively regulating the expression of the cyclin genes RhCYCA1;1 and RhCYCB1;2. To explore the potential mechanism for cytokinin-mediated regulation of RhSCL28 expression, we investigated the cytokinin response factor RhRR1 and determined that it positively regulates RhSCL28 expression. Like RhSCL28, silencing RhRR1 also resulted in smaller petals by decreasing cell number. Taken together, these results reveal that the RhRR1-RhSCL28 module positively regulates petal size by promoting cell division in rose.
RESUMEN
Salix gordejevii is an endemic species in northern China. The analysis of the complete chloroplast genome of S. gordejevii can offer a referential basis for identifying and utilizing Salix germplasm resources. In this study, we obtained chloroplast DNA from S. gordejevii and characterized it. The complete chloroplast genome of S. gordejevii is 155,491 bp in length, comprising a pair of inverted repeats (IR, 27,408 bp), a large single-copy region (LSC, 84,367 bp), and a small single-copy region (SSC, 16,309 bp). We annotated 117 genes in total, including 80 protein-coding genes, 32 tRNA genes, four rRNA genes, and one pseudogene (ycf1). A maximum-likelihood phylogenetic tree was built with MEGA-X and showed that the chloroplast of S. gordejevii has the closest relationship with that of S. magnifica compared to the other reported Salix genomes.