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The Arabidopsis Tóxicos en Levadura (ATL) protein is a subfamily of the E3 ubiquitin ligases, which exists widely in plants and is extensively involved in plant growth and development. Although the ATL family has been identified in other species, such as Arabidopsis, Oryza sativa, and grapevine, few reports on pear ATL gene families have been reported. In this study, 92 PbrATL genes were identified and analyzed from the Pyrus breschneideri genome. Motif analysis and phylogenetic tree generation divided them into nine subgroups, and chromosome localization analysis showed that the 92 PbrATL genes were distributed in 16 of 17 pear chromosomes. Transcriptome data and quantitative real-time polymerase chain reaction (qRT-PCR) experiments demonstrated that PbrATL18, PbrATL41, and PbrATL88 were involved in both pear drought resistance and Colletotrichum fructicola infection. In addition, Arabidopsis thaliana overexpressing PbrATL18 showed greater resistance to drought stress than the wild type (WT), and PbrATL18-silenced pear seedlings showed greater sensitivity to drought and C. fructicola infection than the controls. PbrATL18 regulated plant resistance by regulating chitinase (CHI), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities. This study provided a reference for further exploring the functions of the PbrATL gene in drought resistance and C. fructicola infection.

Abstract In pears, the presence of stone cells adversely affects fruit quality. Pectin methylesterase (PME) plays various roles in plant biology, including lignin biosynthesis. However, only a limited fraction has been functionally characterized, and the distribution and function of PME in many Rosaceae trees remain unexplored. In this study, we identified 396 putative PME family candidate genes, with 81 in Pyrus bretschneideri, 92 in Malus domestica, 62 in Fragaria vesca, 65 in Prunus mume, 15 in Pyrus communis, and 81 in Pyrus pyrifolia. Leveraging insights from model plants, we categorized PME family genes into four groups. Additionally, the evolution of the PME gene family was shaped by various gene duplication events, primarily dispersed duplication, influenced by purifying selection. A specific gene, Pbr031522.1, designated PbPME35, emerged as a candidate associated with lignin biosynthesis in pear fruits, supported by RNA-seq data. The role of PbPME35 in repressing lignification was validated through its overexpression in pear callus and Arabidopsis. Overall, our findings highlight the ability of PbPME35 to reduce lignin content in pear fruit by downregulating the expression levels of lignin biosynthesis genes. These findings provide new insights into the characteristics of PME genes and their role in regulating lignification in pear fruits.

Abstract The yellow stem borer Scirpophaga incertulas is the dominant pest of rice in tropical Asia. However, the lack of genomic resources makes it difficult to understand their invasiveness and ecological adaptation. A high-quality chromosome-level genome of S. incertulas, a monophagous rice pest, was assembled by combining Illumina short reads, PacBio HiFi long sequencing, and Hi-C scaffolding technology. The final genome size was 695.65 Mb, with a scaffold N50 of 28.02 Mb, and 93.50% of the assembled sequences were anchored to 22 chromosomes. BUSCO analysis demonstrated that this genome assembly had a high level of completeness, with 97.65% gene coverage. A total of 14,850 protein-coding genes and 366.98 Mb of transposable elements were identified. In addition, comparative genomic analyses indicated that chemosensory processes and detoxification capacity may play critical roles in the specialized host preference of S. incertulas. In summary, the chromosome-level genome assembly of S. incertulas provides a valuable genetic resource for understanding the biological characteristics of its invasiveness and developing an efficient management strategy.

Abstract Background Glucose can be involved in metabolic activities as a structural substance or signaling molecule and plays an important regulatory role in fruit development. Glucose metabolism is closely related to the phenylpropanoid pathway, but the specific role of glucose in regulating lignin biosynthesis in pear fruit is still unclear. The transcriptome of pear calli generated from fruit and treated with glucose was analyzed to investigate the role of glucose in lignin biosynthesis. Results The treatment of exogenous glucose significantly enhanced the accumulation of lignin in pear calli. A total of 6566 differentially expressed genes were obtained by transcriptome sequencing. Glycolysis was found to be the pathway with significant changes. Many differentially expressed genes were enriched in secondary metabolic pathways, especially the phenylpropanoid pathway. Expression of structural genes (PbPAL, PbHCT, PbCOMT, PbPRX) in lignin biosynthesis was up-regulated after glucose treatment. In addition, glucose might regulate lignin biosynthesis through interactions with ABA, GA, and SA signaling. Several candidate MYB transcription factors involved in glucose-induced lignin biosynthesis have also been revealed. The qRT-PCR analyses showed that the expression pattern of PbPFP at early developmental stage in ‘Dangshansuli’ fruits was consistent with the trend of lignin content. Transient expression of PbPFP resulted in a significant increase of lignin content in ‘Dangshansuli’ fruits at 35 days after full bloom (DAB) and tobacco leaves, indicating that PbPFP (Pbr015118.1) might be associated with the enhancement of lignin biosynthesis in response to glucose treatment. Conclusions PbPFP plays a positive role in regulating lignin biosynthesis in response to glucose treatment. This study may reveal the regulatory pathway related to lignin accumulation in pear calli induced by glucose.