Xue-Jun Pan’s research while affiliated with Guizhou University and other places

Six collections of ascomycetes were obtained from samples collected from dead branches and leaves of Juglans regia in Guizhou and Yunnan provinces, China. By incorporating multigene phylogenetic analysis (ITS, LSU, rpb2, SSU, tef1-α, tub2) supplemented by morphological data, we establish two novel species, namely Helminthosporium guizhouense and Nigrospora yunnanensis. In morphology, H. guizhouense can be distinguished from H. caespitosum by its narrower conidia (13–16 µm vs. 27.3–35.5 µm), and N. yunnanensis is characterized by black, globose conidia (16.2 × 14.4 µm). The phylogenetic results further substantiated them as novel taxa. The present study contributes to our comprehension of the range of fungi found in Juglans regia, thereby expanding our knowledge of the diversity of fungi within this host.

Somatic embryogenesis is a unique method of in vitro regeneration, which can be used in plant reproduction, germplasm conservation, and molecular-assisted breeding. The results showed that the optimum medium for embryogenic callus induction was MS + 6 mg L⁻¹ 6-BA + 1.5 mg L⁻¹ TDZ + 0.5 mg L⁻¹ NAA + 30 g L⁻¹ sucrose + 7 g L⁻¹ agar, and the induction rate was 47.45%. The best somatic differentiation medium was MS + 2 mg L⁻¹6-BA + 1.5 mg L⁻¹ TDZ + 30 g L⁻¹ sucrose + 7 g L⁻¹ agar, and the induction rate of somatic embryos was 54.45%. The optimum medium for embryoid proliferation was MS + 6 mg L⁻¹ 6-BA + 1 mg L⁻¹ NAA + 0.2 mg L⁻¹ TDZ, and the proliferation rate and the multiplication coefficient reached 46.33% and 7.83, respectively. The mature somatic embryos were put into MS, B5, and 1/2MS medium for seedling culture. In MS medium, true leaves grew, complete plants were obtained, and the seedling rate was 88.00%. At the same time, the survival rate of transplanting seedlings in the mixed matrix (peat: organic fertilizer: soil = 1:1:1) was as high as 98%. Cytological observation showed that the somatic embryos underwent globular, heart-shaped, torpedo, and cotyledon stages. This study established a regeneration system of C. × generalis with excellent somatic embryos, and provided basic technical support for the large-scale commercial propagation and germplasm resources protection. It will lay a foundation for further research on gene function and breeding new varieties and ideal research materials for the study of somatic embryogenesis mechanism and genetic transformation of C. × generalis.

Somatic embryogenesis is a unique method of in vitro regeneration, which can be used in plant reproduction, germplasm conservation, and molecular-assisted breeding. The results showed that the optimum medium for embryogenic callus induction was MS+6 mg L ⁻¹ 6-BA+1.5 mg L ⁻¹ TDZ+0.5 mg·L ⁻¹ NAA+30 g·L ⁻¹ sucrose +7 g·L ⁻¹ agar, and the induction rate was 47.45%. The best somatic differentiation medium was MS+2 mg·L ⁻¹ 6-BA+1.5 mg·L ⁻¹ TDZ+30g·L ⁻¹ sucrose +7g·L ⁻¹ agar, and the induction rate of somatic embryos was 54.45%. The optimum medium for embryoid proliferation was MS +6mg·L ⁻¹ 6-BA + 1 mg·L ⁻¹ NAA +0.2mg·L ⁻¹ TDZ, and the proliferation rate and the multiplication coefficient reached 46.33% and 7.83, respectively. The mature somatic embryos were put into MS, B5, and 1/2MS medium for seedling culture. T In MS medium, true leaves grew, complete plants were obtained, and the seedling rate was 88.00%. At the same time, the survival rate of transplanting seedlings in the mixed nutrient soil with the ratio of original soil (peat: organic fertilizer: soil) =1:1:1 was as high as 98%. Cytological observation showed that the somatic embryos underwent globular, heart-shaped, torpedo, and cotyledon stages. This study established a tissue culture and regeneration system of C. × generalis with excellent somatic embryos, and provide basic technical support for the large-scale commercial propagation and germplasm resources protection. It will lay a foundation for further research on gene function and breeding new varieties and ideal research materials for the study of somatic embryogenesis mechanism and genetic transformation of C. × generalis.

Magnolia grandiflora is a widely cultivated ornamental tree in China. In June 2020, a leaf blight disease was observed on M. grandiflora in Guizhou University (26° 44' 57'' N, 106° 65' 94'' E) in Guiyang, China. The initial symptoms on leaves were expanding round necrotic lesions with a grey center and dark brown edge, and twigs were withered when the disease was serious. Of the 100 plants surveyed 65% had symptoms. To isolate the potential causal pathogen, diseased leaves were collected from an M. grandiflora tree at Guizhou University. Isolations from made form the junction between healthy and symptomatic tissue and disinfested by immersing in 75% ethanol for 30 seconds, 3% NaOCl for 2 minutes, and then washed 3 times in sterile distilled water. Symptomatic tissue was then plated on potato dextrose agar (PDA) and incubated at 25ºC with 12-hour light for 3–5 days. Three isolates (GUCC 21235.1, GUCC 21235.2 and GUCC 21235.3) were obtained. Colonies on PDA after 7 d were dark brown, pycnidia embedded in the mydelium were dark brown to black, single and separated. Conidiophores were transparent measuring 7–12.5 × 2.5–4.5 µm (mean = 9.5 × 3.6 µm, n = 30) in length. Conidia were transparent becoming brown when mature with a diaphragm, with round ends measuring, 21–27 × 10–15 µm (mean = 23.6 × 12.6 µm, n = 30). To confirm the pathogen by molecular characterization, four genes or DNA fragments, ITS, LSU, tef1 and β-tubulin, were amplified using the following primer pairs: ITS4-F/ ITS5-R (White et al., 1990), LR0R/ LR5 (Rehner & Samuels, 1994), EF1-688F/ EF1-986R (Carbone & Kohn, 1999) and Bt2a/ Bt2b (O'Donnell & Cigelnik, 1997). The sequences of four PCR fragments of GUCC 21235.1 were deposited in GenBank, and the accession numbers were MZ519778 (ITS), MZ520367 (LSU), MZ508428 (tef1) and MZ542354 (β-tubulin). Bayesian inference was performed based on a concatenated dataset of ITS, LSU, tef1 and β-tubulin gene using MrBayes 3.2.10, and the isolates GUCC 21235.1 formed a single clade with the reference isolates of Diplodia mutila (Diplodia mutila strain CBS 112553). BLASTn analysis indicated that the sequences of ITS, LSU, tef1 and β-tubulin revealed 100% (546/546 nucleotides), 99.82% (568/569 nucleotides), 100% (302/302 nucleotides), and 100% (437/437 nucleotides) similarity with that of D. mutila in GenBank (AY259093, AY928049, AY573219 and DQ458850), respectively. For confirmation of the pathogenicity of this fungus, a conidial suspension (1×105 conidia mL-1) was prepared from GUCC 21235.1, and healthy leaves of M. grandiflora trees were surface-disinfested by 75% ethanol, rinsed with sterilized distilled water and dried by absorbent paper. Small pieces of filter paper (5 mm ×5 mm), dipped with 20 µL conidial suspension (1×105 conidia mL-1) or sterilized distilled water (as control), were placed on the bottom-left of the leaves for inoculation. Then the leaves were sprayed with sterile distilled water, wrapped with a plastic film and tin foil successively to maintain high humidity in the dark dark. After 36 h, the plastic film and tin foil on the leaves was removed, and the leaves were sprayed with distilled water three times each day at natural condition (average temperature was about 25 °C, 14 h light/10 h dark). After 10 days of inoculation, the same leaf blight began to appear on the leaves inoculated with conidial suspension. No lesion was appeared on the control leaves. The fungus was re-isolated from the symptomatic tissue. Based on the morphological information and molecular characterization, the isolate GUCC 21235.1 is D. mutila. Previous reports indicated that D. mutila infects a broad host range and gives rise to a canker disease of olive, apple and jujube (Úrbez-Torres et al., 2013; Úrbez-Torres et al., 2016; Feng et al., 2019). This is the first report of leaf blight on M. grandiflora caused by D. mutila in China.

Eleven coelomycetous fungi were isolated from diseased leaves of Lasia spinosa (Araceae) in Guangxi Province, China. These isolates produced sporodochial and myrothecium-like conidiomata. Multi-gene analyses (ITS, LSU, cmdA, rpb2, tub2 and tef1) showed that these isolates belonged to Xepicula group with a close relationship to X. leucotricha, but formed an independent branch with high bootstrap support. These isolates represent a new species of Xepicula that can be distinguished mainly by setae that are longer than the three other known species. Based on both morphological and molecular analyses, the new species, X. yifeii sp. nov., is described. Further, pathogenicity tests of in vitro and in vivo inoculation experiments showed that X. yifeii is pathogenic to Lasia spinosa leaves.

The objective of this study was to investigate the effect of storage temperature and time on nutrients, bioactive compounds, and antioxidant activities of walnut male inflorescences. The results showed that the moisture, saccharides, fat, protein, amino acids, ascorbic acid, phenolic and flavonoid compound contents, and antioxidant activities of walnut male inflorescences were markedly influenced by storage temperature, and different degrees of decrease in these parameters were observed during the entire storage period. Moreover, higher storage temperature had a more significant effect on the nutrients, bioactive compounds, and antioxidant activities of walnut male flowers, and the loss rate of these components at 25°C was higher than that determined at 4°C. However, the results also presented that the ash and mineral contents did not appear to be influenced significantly by the storage temperature, and slightly significant changes were observed in crude fiber throughout storage, which indicated that the influence of storage on the individual mineral and crude fiber content was minimal. Based on the findings in this study, in order to maximize nutrients concentration, walnut male inflorescences should be kept at 4°C for <6 days and be consumed as fresh as possible.

Edible canna is a productive starch source in some tropical and semitropical regions. In these regions, water deficit stress is one of factors that limit the crop yield. In the present study, we investigated seven physiological indexes and photosynthetic responses of three edible canna (Canna edulis Ker.) cultivars ('PLRF', 'Xingyu-1', and 'Xingyu-2') under 35 days drought stress. Our results indicated that drought treatment caused visible wilting symptoms in all cultivars, especially in 'Xingyu-1'. Coupled with the increase of wilting symptoms, relative water content (RWC) and chlorophyll content decreased progressively, malondialdehyde (MDA) content gradually increased, and key antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities increased first and then decreased in all three cultivars. The effect of water stress was more pronounced in 'Xingyu-1' than in 'PLRF' and 'Xingyu-2', and in lower leaves than in upper leaves. In addition, 35 days drought stress also significantly reduced the photosynthetic capacity. Consistent with antioxidant parameters, photosynthetic changes of 'Xingyu-2' were less than those of the other cultivars under water deficit stress. Drought stress caused a significant increase of water use efficiency (WUE) in 'Xingyu-2', but little in 'PLRF', and obvious decrease in 'Xingyu-1'. These results indicated that 'Xingyu-2' was more tolerant to drought stress than 'PLRF' and 'Xingyu-1' by maintaining lower lipid peroxidation and higher antioxidant enzyme activities.

In order to acquire the difference among Vitis species and individuals, the photosynthetic parameters of twenty-five lines in seven species were measured using Li-6400 portable photosynthesis system. The results showed that photosynthesis characteristics was significantly different among wild Vitis species, Pn of Vitis bellula was the highest, the second was V. davidii ,and V. adenoclada was the lowest .The diversity of photosynthesis indexes among different wild Vitis individuals was abundant. The difference among individuals of V. flexuosa was the biggest. If the climates of origin were similar, the photosynthesis characteristics were alike. If the climates of origin were significantly different, the photosynthesis characteristics were significantly different. The regulation mechanism of Pn was diverse, and the non-stomatal regulation factors were universal in wild Vitis.