Environment and Plant Protection Research Institute

Morus macroura with low chilling requirement is one of the primary cultivated mulberry varieties, demonstrates early and abundant fruiting characteristics with high yield and significant economic value, however, the genetic mechanisms of M. macroura are not well understood. In this study, we constructed a chromosome-level genome assembly and annotation of M. macroura. The contig-level genome was initially assembled in 322.62 Mb with a contig N50 of 17.98 Mb from PacBio HiFi reads. With Hi-C sequencing data scafolding, 99.34% of the initially assembled sequences were anchored and orientated onto 14 pseudo-chromosomes, generating a genome of 318.59 Mb with a contig N50 of 17.98 Mb. We identifed 173.34 Mb (54.41%) of repetitive sequences and 2,970 non-coding RNAs in the genome. A total of 21,824 protein-coding genes were predicted, with 21,181 (97.05%) functionally annotated genes. We found 97.21% and 97.46% complete BUSCO genes in the pseudo-chromosomes genome and predicted gene datasets. The high-quality assembly serves as a foundational resource for decoding regulatory networks of year-round fruiting and low-chilling adaptation in M. macroura.

Fruit shape is a commercially important trait in litchi, yet the genetic mechanisms that regulate its development remain largely unresolved. OVATE Family Proteins (OFPs) are plant-specific transcriptional regulators known to play key roles in fruit morphology, organ growth, and overall plant development. In this study, we identified 14 OFP genes distributed across eight chromosomes in the litchi genome. Phylogenetic reconstruction and conserved motif analyses demonstrated that all LcOFPs contain the characteristic OVATE domain and can be grouped into three subfamilies based on motif composition. Promoter cis-element analysis further suggested that LcOFPs may respond to diverse phytohormone signals and abiotic stresses, indicating their involvement in multiple regulatory pathways. Integrated RNA-seq and RT-qPCR analyses revealed that LcOFP3, LcOFP6, LcOFP10, LcOFP13, and LcOFP14 show tissue-specific expression patterns and dynamic transcriptional changes during fruit development in two cultivars with contrasting fruit sizes. Heterologous overexpression of LcOFP3 significantly modified fruit morphology in tomato. These findings clarify the genetic mechanisms through which OFP genes regulate fruit shape in litchi and highlight promising genetic targets for future litchi breeding and improvement.

Banana, a globally significant economic fruit, faces major production constraints due to pests and diseases. Recently, banana fruit rot and rachis rot have emerged in several banana plantations across Guangxi, China. This study aims to identify the pathogens of the diseases and investigate their potential interrelations. Pathogenicity tests were conducted on banana plants with eight representative strains isolated from the rachides and fruits of Cavendish (AAA) and Pisang Awak (ABB) banana cultivars. Pathogen identification was achieved through morphological, physiological, and biochemical tests coupled with phylogenetic analysis based on multigene sequences. Comparative analyses were then performed on growth and pathogenic virulence of the bacteria isolated from the fruits and rachides of the two banana cultivars. The pathogens causing fruit rot and rachis rot in Cavendish bananas were identified as Dickeya zeae, while those responsible for the same diseases in Pisang Awak bananas were identified as D. fangzhongdai. In addition, D. zeae strains exhibited optimal growth at pH 7.0, whereas D. fangzhongdai strains showed optimal growth at pH 7.5. Strains isolated from rachides exhibited higher motility and pectinase activity compared with those isolated from fruits of the same host. D. zeae exhibited significantly higher virulence toward Cavendish bananas, whereas D. fangzhongdai showed greater virulence toward Pisang Awak. This study provides the first evidence of D. zeae causing both rachis and fruit rot in bananas and D. fangzhongdai as a causal agent of banana fruit rot. Furthermore, each pathogen demonstrated distinct host preferences, with D. zeae predominantly infecting Cavendish cultivars and D. fangzhongdai targeting Pisang Awak. These findings offer new insights into the bacterial rot diseases of bananas caused by Dickeya spp.

[This corrects the article DOI: 10.3389/fpls.2025.1715720.].