Calcium (Ca²⁺) plays an important role in determining plant growth and development because it maintains cell wall and
membrane integrity. Therefore, understanding the role of Ca2+ in carbon and lipid metabolism could provide insights
into the dynamic changes in cell membranes and cell walls during the rapid elongation of cotton fibers. In the present
study, we found that the lack of Ca²⁺ promoted fiber elongation and rapid ovule expansion, but it also caused tissue
browning in the ovule culture system. RNA-sequencing revealed that Ca²⁺ deficiency induced cells to be highly oxidized,
and the expression of genes related to carbon metabolism and lipid metabolism was activated significantly. All gene
members of nine key enzymes involved in glycolysis were up-regulated, and glucose was significantly reduced in Ca²⁺
deficiency-treated tissues. Ca²⁺ deficiency adjusted the flowing of glycolysis metabolic. However, low K⁺ recovered
the expression levels of glycolysis genes and glucose content caused by Ca2+ deficiency. Electrospray ionizationtandem
mass spectrometry technology was applied to uncover the dynamic profile of lipidome under Ca²⁺ and K⁺
interacted conditions. Ca²⁺ deficiency led to the decrease of fatty acid (FA), diacylglycerol (DAG), glycolipid and the
significant increase of triacylglycerol (TAG), phospholipid phosphatidylethanolamine (PE), phosphatidylglycerol (PG),
and PC (phosphatidylcholine). Low K⁺ restored the contents of FA, phospholipids, and glycolipids, effectively relieved
the symptoms caused by Ca²⁺ deficiency, and recovered the development of fiber cells. This study revealed dynamic
changes in transcript and metabolic levels and uncovered the signaling interaction of Ca²⁺ deficiency and low K⁺ in
glycolysis and lipid metabolism during fiber development.

Mitochondria influence plant growth, fertility, and adaptation. Sugarcane (Saccharum hybrids) is the most important sugar and energy crop worldwide, and S. spontaneum and S. arundinaceum are excellent parental germplasm. However, few studies have been conducted on the mitochondrial genomes of sugarcane and related species. In this study, the mitogenomes of one S. arundinaceum, one S. spontaneum, and five sugarcane cultivars were assembled. The results showed that the sizes of these mitogenomes, encoding 33 protein-coding genes (PCGs), were between 445,578 and 533,662 bp, with a GC content of 43.43%-43.82%. The major structures of S. arundinaceum comprised three small rings, S. spontaneum had one ring and one linear structure, and sugarcane had two rings; there were multiple potential conformations due to repeat-mediated recombination. Furthermore, we developed an intron marker SAnad4i3 that can distinguish these species. Between 540 and 581 and from C to U RNA editing sites were identified in the PCGs, with six RNA editing sites were associated with the creation of start or stop codons in S. arundinaceum, and five sites each in S. spontaneum and the sugarcane hybrids were observed. Notably, 30-37 fragments homologous to chloroplast DNA were identified, with the highest number found in S. spontaneum. During evolution, these mitogenomes may have undergone multiple genomic reorganization and gene transfer events and lost eight PCGs. Collectively, this study reveals the genetic diversity and complexity of the Saccharum complex by providing a scientific basis for further germplasm identification and evolutionary research.