First report of Stagonosporopsis cucurbitacearum Causing Gummy Stem Blight on Trichosanthes kirilowii Maxim. in China.

Trichosanthes kirilowii Maxim. (Cucurbitaceae), one of the Chinese herbal medicines, is an economically important crop in Anhui Province, China. In recent years, gummy stem blight disease, a major disease of cucurbits, was widespread in many T. kirilowii plantations. The initial symptoms on the naturally infected stems appeared as dark brown water-soaked lesions, and as the disease progressed, vines of T. kirilowii gradually withered. On leaves, brown water-soaked lesions were visible initially, and then lesions enlarged and coalesced, resulting in extensive necrosis of leaves. On fruit, lesions covered with the white mycelium were nearly circular and tan to brown initially. Subsequently, the diseased fruit turned black and rotten commonly known as fruit rot or black rot. A Stagonosporopsis-like organism was consistently isolated from symptomatic stems, leaves and fruits. Fungal isolates were initially white and later turned dark grey or black with woolly to floccose aerial mycelium on PDA medium. Twenty-four isolates from different plantations were selected for further morphological studies. Pycnidia and conidia were formed after inoculating on cucumber fruit for 3 days. Pycnidia were globose to sub-globose, brown, ostiolate and 106.7 to 213.6 µm (average 160.1 µm, n = 50) in diameter. Conidia were hyaline, ellipsoidal, aseptate or one-septate, slightly constricted at the septa, 6.1 to 13.6 × 3.5 to 4.8 µm (average 9.9 × 4.1 µm, n = 50), and contained two or more oil drops. Three different loci of the genomic DNA, including the nuclear ribosome DNA internal transcribed spacer (ITS), RNA polymerase II second-largest subunit (RPB2), and ß-tubulin (TUB2) genes., were amplified using primers ITS1/ITS4 (White et al. 1990), RBP2DF/RBP2DR (Lawrence et al. 2013), and T1/ß-Sandy-R (O' Donnell and Cigelnik 1997; Stukenbrock et al. 2012), respectively and sequenced. A phylogenetic tree was built based on analysis of ITS, RPB2, and TUB2 sequences that deposited in GenBank (MW485497-MW485502 for ITS, MW531661-MW531666 for RPB2, and MW531667-MW531672 for TUB2), using the maximum likelihood method. The phylogenetic tree showed that the isolates fell into a single clade with S. cucurbitacearum. On the basis of morphological and molecular characteristics, the isolates obtained from T. kirilowii were identified as Stagonosporopsis cucurbitacearum. Pathogenicity tests were carried out on stems and leaves of 4-week-old T. kirilowii seedlings and on immature fruit collected from adult T. kirilowii plants. The epidermis, previously injured with a syringe needle, was inoculated with 5-mm-diameter mycelial plugs, and the inoculated areas were then wrapped in water-soaked cotton. Controls were similarly inoculated with agar plugs. The diameters of lesions were measured in two perpendicular directions. Re-isolations from the stem and leaf lesions were performed on the PDA medium. Stagonosporopsis cucurbitacearum, was re-identified based on its colony and conidial characteristics and, therefore, completed Koch's postulates. Gummy stem blight caused by S. cucurbitacearum has been reported in a wide range of hosts, including cucumber, luffa, pumpkin, gourd, muskmelon, cantaloupe, and watermelon (Jiang et al. 2015; Keinath 2011; Zhao et al. 2019). To our knowledge, this is the first report of gummy Stem blight disease on T. kirilowii caused by S. cucurbitacearum in China. The research provides a basis for the development and implementation of effective management strategies. Pathogenicity tests were carried out on stems and leaves of 4-week-old T. kirilowii seedlings and on immature fruits collected from adult T. kirilowii plants. The epidermis, previously injured with a syringe needle, was inoculated with 5-mm-diameter mycelial plugs, and the inoculated areas were then wrapped in water-soaked cotton. Controls were treated similarly but inoculated with agar plugs. Diameters of lesions were measured in two mutually perpendicular directions. Reisolations from the lesions were performed on PDA medium, and was re-identified based on its colony and conidial characteristics to complete Koch's postulates. Gummy stem blight caused by S. cucurbitacearum have been reported in a wide range of hosts, including cucumber, luffa, pumpkin, gourd, muskmelon, cantaloupe, and watermelon (Jiang et al. 2015; Keinath 2011; Zhao et al. 2019). To our knowledge, this is the first report of gummy Stem blight disease on T. kirilowii caused by S. cucurbitacearum in China. The research provides a basis for the development and implementation of effective management strategies.

Selection of Beauveria isolates pathogenic to adults of Nilaparvata lugens.

The brown planthopper, Nilaparvata lugens Stål (Hemiptera: Delphacidae), is a destructive invasive pest and has become one of the most economically-important rice pests in China. Effective control measures are desperately needed. Entomopathogenic fungi, such as Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Clavicipitaceae) and B. brongniartii (Saccardo), have shown great potential for the management of some sucking pest species. In this study, to explore alternative strategies for sustainable control of the sucking pest population, nine isolates of Beauveria from different pests were bioassayed under the concentrated standard spray of 1000 conidia/mm(2) in laboratory. The cumulative mortalities of adults ranged from 17.2 to 79.1% 10 days after inoculation. The virulence among all tested isolates exhibited significant differences (at p = 0.05). The highest virulent isolate was Bb09, which killed 79.1% of the treated insects and had a median lethal time of 5.5 days. Its median lethal concentration values were estimated as 134 conidia/mm(2) on day 10. The chitinase activities of nine isolates were also assayed. The results showed that the chitinase activity (18.7 U/mg) of isolate Bbr09 was the highest among all tested isolates. The biological characteristics of these strains, including growth rate, sporulation, and germination rate, were further investigated. The results showed that strain Bbr09 exhibited the best biological characteristics with relatively higher hyphal growth rate, the highest spore production, and the fastest spore germination. The isolate of Bbr09 had strong pathogenicity and exhibited great potential for sustainable control of N. lugens.

Low docosahexaenoic acid content in plasma phospholipids is associated with increased non-alcoholic fatty liver disease in China.

A large proportion of the Chinese population is now at risk of non-alcoholic fatty liver disease (NAFLD). We aimed to investigate the relationship between plasma phospholipids (PL) fatty acids and the risk of NAFLD. One hundred NAFLD patients and 100 healthy subjects were recruited in Hangzhou, China. Plasma PL and selected biochemical and hematological parameters were analyzed by using standard methods. Stepwise logistic regression was used to identify independent risk factors of NAFLD. Plasma PL total saturated fatty acid (SFA), C20:3n-6, serum alanine aminotransferase, high-density lipoprotein cholesterol, and body mass index were independent risk factors of NAFLD. The risk of NAFLD was significantly increased with higher quartiles of plasma PL total SFA (P for trend = 0.028) and C20:3n-6 (P for trend <0.001); plasma PL docosahexaenoic acid (C22:6n-3) was significantly lower in NAFLD patients than in controls (P = 0.032) and the OR of NAFLD in the highest quartile of C22:6n-3 was 0.41 (95 % CI = 0.17-0.97) compared with the lowest quartile. In conclusion, plasma PL total SFA and C20:3n-6 are positively correlated with the risk of NAFLD, while C22:6n-3 is negatively correlated with the risk of NAFLD.

Increased plasma n-3 polyunsaturated fatty acid is associated with improved insulin sensitivity in type 2 diabetes in China.

Increased tissue n-3 polyunsaturated fatty acid (PUFA) is associated with improved insulin sensitivity in type 2 diabetes. However, this relationship among Chinese is not clear. To investigate the relationship between plasma phospholipids (PL) fatty acid composition and insulin resistance (IR) in type 2 diabetes mellitus, 186 type 2 diabetes and 180 healthy subjects were studied in this case-control study. In the sex, age and BMI controlled partial correlation, homeostasis model assessment (HOMA)-IR and blood glucose was significantly negatively correlated with plasma PL n-3 PUFA, 20:5n-3 and ratio of n-3:n-6 (p<0.01), and positively correlated with n-6 PUFA (p<0.001) and saturated fatty acid (p<0.05) in the diabetes patients. PL 22:6n-3 was also significantly negatively correlated with HOMA-IR (p<0.01), but not with blood glucose. Fasting insulin was significantly negatively correlated with plasma PL n-3 PUFA, 20:5n-3, 22:6n-3 and ratio of n-3:n-6 (p<0.01). The 18:3n-3 was not associated with HOMA-IR and fasting insulin. The results suggested that increased plasma PL n-3 PUFA, 20:5n-3, 22:6n-3 and ratio of n-3:n-6 PUFA was associated with decreased HOMA-IR in type 2 diabetes. Increased plasma PL n-3 PUFA improves insulin sensitivity in type 2 diabetes.