Huiyun Zhang

Litchi chinensis var. fulvosus is an important wild litchi resource in Yunnan, China, valued for favorable agronomic traits such as early flowering, early ripening, multiple flowering cycles, and high fruit-setting ability. However, its genetic diversity and population structure remain poorly understood. In this study, 192 accessions were collected from ten counties in Yunnan Province to evaluate their geographic distribution, leaf phenotypic variation, molecular diversity, population structure, and core collection composition. Eight descriptive leaf traits, nine quantitative leaf traits, and ISSR genotyping data from seven primers were analyzed. The accessions were distributed across an altitudinal range of 169–1470 m, with clear habitat differentiation among trees of different ages. Morphological analysis revealed substantial leaf variation, with mean diversity indices of 1.19 for descriptive traits and 2.76 for quantitative traits. ISSR analysis generated 49 scorable bands, of which 34 were polymorphic, corresponding to a polymorphism rate of 68.45%. The mean Shannon–Wiener diversity index was 0.3101, indicating detectable but relatively limited molecular diversity. Integrated phenotypic and molecular analyses divided the germplasm into two subpopulations. A core collection comprising 30 accessions (about 15% of the initial population) showed the best balance between sampling efficiency and diversity retention. These results provide a practical basis for the conservation, evaluation, and efficient utilization of L. chinensis var. fulvosus genetic resources and will support breeding and genetic improvement of litchi.

Background: Plant-specific TIFY proteins are widely found in terrestrial plants and play important roles in plant adversity responses. Although the genome of loquat at the chromosome level has been published, studies on the TIFY family in loquat are lacking. Therefore, the EjTIFY gene family was bioinformatically analyzed by constructing a phylogenetic tree, chromosomal localization, gene structure, and adversity expression profiling in this study. Results: Twenty-six EjTIFY genes were identified and categorized into four subfamilies (ZML, JAZ, PPD, and TIFY) based on their structural domains. Twenty-four EjTIFY genes were irregularly distributed on 11 of the 17 chromosomes, and the remaining two genes were distributed in fragments. We identified 15 covariate TIFY gene pairs in the loquat genome, 13 of which were involved in large-scale interchromosomal segmental duplication events, and two of which were involved in tandem duplication events. Many abiotic stress cis-elements were widely present in the promoter region. Analysis of the Ka/Ks ratio showed that the paralogous homologs of the EjTIFY family were mainly subjected to purifying selection. Analysis of the RNA-seq data revealed that a total of five differentially expressed genes (DEGs) were expressed in the shoots under gibberellin treatment, whereas only one gene was significantly differentially expressed in the leaves; under both low-temperature and high-temperature stresses, there were significantly differentially expressed genes, and the EjJAZ15 gene was significantly upregulated under both low- and high-temperature stress. RNA-seq and qRT-PCR expression analysis under salt stress conditions revealed that EjJAZ2, EjJAZ4, and EjJAZ9 responded to salt stress in loquat plants, which promoted resistance to salt stress through the JA pathway. The response model of the TIFY genes in the jasmonic acid pathway under salt stress in loquat was systematically summarized. Conclusions: These results provide a theoretical basis for exploring the characteristics and functions of additional EjTIFY genes in the future. This study also provides a theoretical basis for further research on breeding for salt stress resistance in loquat. RT-qPCR analysis revealed that the expression of one of the three EjTIFY genes increased and the expression of two decreased under salt stress conditions, suggesting that EjTIFY exhibited different expression patterns under salt stress conditions.

Longan (Dimocarpus longan Lour.) is of great economic significance in South China for its unique taste and nutritional properties. However, longan breeding is mainly based on seedling selection, which generally results in small fruits, low flesh recovery, and few seedless germplasm. Triploid breeding is a central way to improve these problems. In this study, microspore chromosomes were doubled by colchicine and high-temperature treatment to create triploids in longans. The relationship between the development process of male gametophyte of longans and the morphological changes of male flower buds was established. Cytological observation showed that when the male flower buds were in stage I (when the diameter of the flower bud is 1.4–2.0 mm), most of the microspores were at the pachytene to diakinesis stage of meiosis, and the chromosome doubling induction effect was the best at this stage. The results showed that the 2n pollen rate induced by a high temperature of about 38 °C was higher than that induced by colchicine treatment. The highest 2n pollen rate was 5.7% and 5.5% based on the microscopic measurement method and the abnormal separation in tetrad stage estimation method, respectively. Four triploids were successfully obtained from artificial pollination with 2n pollen, with a triploid induction rate of 0.6%. This study will promote ploidy breeding in longan.

Chinese silkworm (Antheraea pernyi) eggs are used as factitious hosts of Anastatus fulloi, and refrigeration of these eggs is essential for large-scale rearing of A. fulloi. We studied the effects of cold storage of A. pernyi eggs on egg quality and the fitness of A. fulloi reared on the eggs. Four cold storage treatments and two cold storage periods were assessed. The 0–3 °C refrigerator treatment was unsuitable for long-term (>70 days) storage. Cold storage at −5 °C and −18 °C increased the loss rate of A. pernyi eggs, but there was no significant difference between the control and 0–3 °C water bath treatment. The parasitism rate of A. fulloi was reduced when A. pernyi eggs were refrigerated for 6 or 12 months. There were no obvious differences in eclosion rate and percentage of females between control and eggs subjected to 6-month storage in 0–3 °C, −5 °C, and −18 °C water bath treatments. However, the eclosion rate and percentage of females decreased sharply when the storage period was 12 months. The overall eclosion rate of A. fulloi was reduced at the prolonged refrigeration time. Cold storage reduced host egg quality and their fitness suitability for A. fulloi. To minimize losses in the large-scale rearing of A. fulloi, A. pernyi eggs should be refrigerated in a 0–3 °C or −5 °C water bath treatment, and the storage period should not exceed 6 months.