Karyotype Description and Comparative Chromosomal Mapping of 5S rDNA in 42 Species.

This study was conducted to evaluate the 5S rDNA site number, position, and origin of signal pattern diversity in 42 plant species using fluorescence in situ hybridization. The species were selected based on the discovery of karyotype rearrangement, or because 5S rDNA had not yet been explored the species. The chromosome number varied from 14 to 160, and the chromosome length ranged from 0.63 to 6.88 µm, with 21 species having small chromosomes (<3 µm). The chromosome numbers of three species and the 5S rDNA loci of nineteen species are reported for the first time. Six 5S rDNA signal pattern types were identified. The 5S rDNA varied and was abundant in signal site numbers (2-18), positions (distal, proximal, outside of chromosome arms), and even in signal intensity. Variation in the numbers and locations of 5S rDNA was observed in 20 species, whereas an extensive stable number and location of 5S rDNA was found in 22 species. The potential origin of the signal pattern diversity was proposed and discussed. These data characterized the variability of 5S rDNA within the karyotypes of the 42 species that exhibited chromosomal rearrangements and provided anchor points for genetic physical maps.

Leaf spot disease on Juglans regia caused by Ragnhildiana diffusa in China.

Juglans regia L. is commercially important for its edible nuts, which is a major species of walnut trees in Sichuan Province (Luo et al. 2020). In September 2021, brown leaf spot symptoms were observed on roughly 75% of 60 J. regia trees surveyed in an orchard of Chongzhou city (30°40'6''N, 103°40'18''E). Initially, the lesions measuring 2-10 mm were reddish to brown with a yellowish halo, then increased in size and coalesced to cover the whole leaf, eventually resulting in severe defoliation. Six symptomatic leaves from different trees were collected, and a single fungal isolate was obtained from each of the sampled leaves using single-spore isolation (Chomnunti et al. 2014). The isolates were incubated on potato dextrose agar (PDA) with a 12h photoperiod at 25 ℃, and deposited at the Culture Collection of Sichuan Agricultural University. Colonies were identical with black center and reddish-brown periphery, and the diameter reached 2 cm after 7 days. On the host, conidiophores were mostly reduced to conidiogenous cells, with prominent and thickened conidiogenous loci. Conidia were light green to light brown, and curved with a thickened and darked hilum at the base, 0-17 septate, tapering toward the distal end, and measuring 20-120 × 3-5 µm ((x ) ̅= 56 × 4, n = 30). Morphological characteristics fit the description of Ragnhildiana diffusa (Heald & F.A. Wolf) Videira & Crous (Synonym: Sirosporium diffusum (Heald & F. A. Wolf) Deighton) (Poletto et al. 2017). The internal transcribed spacer (ITS) region, the large subunit of the nrDNA (LSU), and RNA polymerase II second largest subunit (rpb2) were amplified by polymerase chain reaction and sequenced with primers ITS5/ITS4 (White et al. 1990), LR0R/LR5 (Vilgalys & Hester 1990), fRPB2-5F/Rpb2-R3 (Liu et al. 1999, Videira et al. 2017), respectively. The nucleotide blast of the two isolates (SICAUCC 22-0077, SICAUCC 22-0078) showed 99.7% and 99.5% (ITS, 472/473 bp, 471/473 bp), 100% (LSU, 725/725 bp, 725/725 bp), 99.8% (rpb2, 866/867 bp, 866/867 bp) identities with the ex-type strain of Ragnhildiana diffusa (CBS 106.14). The phylogenetic tree combined with ITS, LSU, and rpb2 genes and morphological characteristics confirmed the identification as R. diffusa. These sequences of the three gene regions of two isolates were deposited in GenBank with accession numbers ON409525 and ON409526 (ITS), ON409559 and ON409560 (LSU), ON417473 and ON417474 (rpb2), respectively. The isolate SICAUCC 22-0077 was used for pathogenicity test to fulfill Koch's postulates. Three leaves of each walnut seedlings (2-year-old seedlings) were inoculated by placing a mycelium plug onto fresh wounds on the upper leaf surface punctured via a fine needle (0.7 mm in diameter), and three replicate seedlings were inoculated. For the control, a sterile PDA plug was placed on the same number of replicate leaves on the plants. The inoculated and control plants were placed in a growth chamber at 25°C with relative humidity >80% and a 12-h photoperiod. Irregular light to dark brown spots developed on inoculated leaves after twenty days, and no symptoms were observed on controls. The re-isolation and examination of the fungus showed it to be morphologically and phylogenetically identical to the originally isolated pathogen. R. diffusa has been described on J. regia in Mexico (Farr & Rossman 2022). To our knowledge, this is the first report of R. diffusa causing brown leaf spot on J. regia in China. The identification of the pathogen will provide a basis for disease management in walnut planting areas.

Insight into the Systematics of Novel Entomopathogenic Fungi Associated with Armored Scale Insect, Kuwanaspis howardi (Hemiptera: Diaspididae) in China.

This study led to the discovery of three entomopathogenic fungi associated with Kuwanaspis howardi, a scale insect on Phyllostachys heteroclada (fishscale bamboo) and Pleioblastus amarus (bitter bamboo) in China. Two of these species belong to Podonectria: P. kuwanaspidis X.L. Xu & C.L. Yang sp. nov. and P. novae-zelandiae Dingley. The new species P. kuwanaspidis has wider and thicker setae, longer and wider asci, longer ascospores, and more septa as compared with similar Podonectria species. The morphs of extant species P. novae-zelandiae is confirmed based on sexual and asexual morphologies. Maximum likelihood and Bayesian inference analyses of ITS, LSU, SSU, tef1-α, and rpb2 sequence data provide further evidence for the validity of the two species and their placement in Podonectriaceae (Pleosporales). The second new species, Microcera kuwanaspidis X.L. Xu & C.L. Yang sp. nov., is established based on DNA sequence data from ITS, LSU, SSU, tef1-α, rpb1, rpb2, acl1, act, cmdA, and his3 gene regions, and it is characterized by morphological differences in septum numbers and single conidial mass.

The complete chloroplast genome of Chimonobambusa hejiangensis.

Chimonobambusa hejiangensis is of the unique edible bamboo specie of high quality in China. We studied the complete chloroplast(cp) genome of C. purpurea in this study. The cp genome of C. hejiangensis (GenBank accession: MW186792) was 138,911 bp in length, including a large single-copy (LSC) region of 82,498 bp, a small single-copy (SSC) region of 12,743 bp and a pair of inverted repeated (IR) regions of 21,835 bp. The genome contained 133 genes, including 86 protein-coding genes, 39 tRNA genes, and 8 rRNA genes. Based on 39 cp genomes, we used the phylogenetic analysis to build phylogenetic tree, indicating that C. hejiangensis is closely related to C. tumidissinoda. Also, the phylogenetic relationship of lineages might be (Hsuehochloa + (((Shibataea clade + Arundinaria clade) + Indocalamus wilsonii) + ((Bergbambos + Indocalamus) + (((African alpine bamboos + Gaoligongshania) + (Chimonocalamus + Kuruna))+(Thamnocalamus + Phyllostachys clade))))). It could be devoted to phylogenetic analysis of Arundinarieae.

The complete chloroplast genome of Chimonobambusa purpurea (Bambusatae).

Chimonobambusa purpurea is one of the important bamboo species in southwest of China. We studied the complete chloroplast (cp) genome of C. purpurea in this study. The cp genome of C. purpurea (GenBank accession: MW030500) was 139,574 bp in length, including a large single-copy (LSC) region of 83,171 bp, a small single-copy (SSC) region of 12,811 bp, and a pair of inverted repeated (IR) regions of 21,796 bp. And the genome contained 133 genes, including 86 protein-coding genes, 39 tRNA genes, and 8 rRNA genes. Based on 30 cp genomes, we used the phylogenetic analysis to build phylogenetic tree, indicating that C. purpurea is closely related to C. tumidissinoda.

Morpho-molecular diversity of Linocarpaceae (Chaetosphaeriales): Claviformispora gen. nov. from decaying branches of Phyllostachys heteroclada.

In this paper, Claviformispora gen. nov. in Linocarpaceae is introduced from Phyllostachys heteroclada in Sichuan Province, China. The new genus is characterised by its distinct morphological characters, such as ostiole with periphyses, asci with a thick doughnut-shaped, J- apical ring and clavate ascospore without septum-like band and appendage. Maximum Likelihood and Bayesian Inference phylogenetic analyses, based on DNA sequence data from ITS, LSU, SSU and TEF-1α regions, provide further evidence that the fungus is a distinct genus within this family. The new genus is compared with similar genera, such as Linocarpon and Neolinocarpon. Descriptions, illustrations and notes are provided for the new taxon.

First Report of Anthracnose Caused by Colletotrichum karstii on Fatsia japonica in Sichuan, China.

Fatsia japonica (Thunb.) Decne. & Planch. (Araliaceae), an evergreen shrub, is widely planted in urban settings at the south of the Yangtze river in China. Leaf-spot symptoms were observed on 120/200 F. japonica plants at Sichuan Agricultural University. Initially, yellowish spots appeared on the leaves and became white with age. The spots continued to expand with time developing irregular margins eventually encompassing the entire leaf. Eventually, diseased leaves became curled and died. Four single-spore isolates were obtained following Chomnunti et al. (2014). The colonies developed on potato dextrose agar (PDA) were white to grey with fluffy aerial hyphae. The base of the mycelium was yellow. On the host conidiomata circular to elliptical, measured 108-335 × 107-250 µm (n=20). Conidiophores were bell-shaped to cylindrical, hyaline, usually 1-celled, unbranched, 9.7-23.6(-28) × 3.5-5.5 µm (x̅ =16.5 × 4.6 µm, n=15). Conidia measured 12.5-17.6 × 5.1-7.9 µm (x̅ =14.9 × 6.7 µm, n=25), were hyaline, straight, unicellular, cylindrical. Appressoria formed abundantly on slides, measured 12.4-25.4(-29.6) × 6.3-18.4 µm (x̅ =18.9 × 13.4 µm, n=30), were dark brown to black, elliptical to irregular. Ascomata on PDA were brown to dark brown, global, covered by aerial mycelium, and setae were absent. Ascospores measured 13.2-19.1 × 4.0-6.1 µm (x̅ =16.0 × 4.8 µm, n=20), and one-celled, hyaline, slightly curved. The representative isolate SICAUCC 20-0010 was used for Genomic DNA extraction following the instructions of Plant Genomic DNA extraction kitTM (Tiangen, China), and the internal transcribed spacer (ITS, MT393946), glyceraldehyde-3-phosphate dehydrogenase (GAPDH, MT425977), beta-tubulin (TUB2, MT425978), chitin synthase (CHS-1, MT425976) and actin (ACT, MT425975) genes were amplified with ITS5/ITS4 (White et al. 1990), GDF/GDR (Guerber et al. 2003), T1/Bt2b (O'Donnell et al. 1997), CHS-79F/CHS-354R and ACT-512F/ACT-783R (Carbone et al. 1999) primers, respectively. ITS, GAPDH, CHS-1 and ACT blast showed 100% homology with sequences of Colletotrichum karstii (Yang et al. 2011, Damm et al. 2012, Xu et al. 2019), viz. JQ005186 (555/555 bp), MK359214 (238/238 bp), JQ005360 (274/274 bp), MK359211 (269/269 bp), respectively. TUB2 showed 99.60% homology with sequences JQ005620 (495/497 bp). The fungus was identified as C. karstii based on morphology and a multigene phylogeny (Fig. 1). Four leaves from each of three healthy F. japonica plants were sprayed with a conidial suspension (1 × 105 conidia/ml) of the isolate SICAUCC 20-0010. Two additional mock-inoculated control plants were sprayed with sterile distilled water. Plants were incubated in a greenhouse at 26℃ and 90% relative humidity with a 12-h photoperiod. The leaves developed chlorotic lesions 6 days post-inoculation and by twenty-two days post-inoculation the remaining signs and symptoms had developed. No symptoms developed on the mock-inoculated controls. The fungus isolated from inoculated plants was morphologically identical to the original pathogen, fulfilling Koch's postulates. The anthracnose on F. japonica caused by C. fructicola and C. gloeosporioide have been reported in China (Wang 2007, Shi et al. 2017). However, this is the first report of anthracnose caused by C. karstii on F. japonica. Field observations indicated that this disease mainly occurs on old and weakened leaves. This disease affects the aesthetic appearance of the plants reducing their appeal as landscape plants.

The complete mitochondrial genome of the fig weevil, Aclees cribratus (Coleoptera: Curculionidae).

Aclees cribratus Gyllenhyl (Coleoptera: Curculionidae) is an important pest of fig. In this study, the complete mitogenome of A. cribratus was determined, which was 17,329 bp in length and contained 37 genes, including 13 protein-coding genes (PCGs), 2 rRNA, 22 tRNA genes, and 2 control regions. The phylogenetic analysis based on mitogenomes showed that A. cribratus is the sister group of Molytinae.