NHL (NDR1/HIN1-like) genes play crucial roles in pathogen induced plant responses to biotic stress. Here, we report the possible function of NHL6 in plant response to abscisic acid (ABA) and abiotic stress. NHL6 was highly expressed in non-germinated seeds, and its expression was strongly induced by ABA and multiple abiotic stress signals. Loss-of-function of NHL6 decreased sensitivity to ABA in the early developmental stages including seed germination and post-germination seedling growth of the nhl6 mutants. However, overexpression of NHL6 increased sensitivity to ABA, salt and osmotic stress of the transgenic plants. Further studies indicated that the increased sensitivity in the 35S::NHL6 overexpressing plants could be a result of both ABA hypersensitivity and increased endogenous ABA accumulation under the stress conditions. It was also seen that the ABA-responsive element binding factors AREB1, AREB2 and ABF3 could regulate NHL6 expression at transcriptional level. Our results indicate that NHL6 plays an important role in the abiotic stresses-induced ABA signaling and biosynthesis, particularly during seed germination and early seedling development in Arabidopsis.

The Arabidopsis vacuolar H⁺-pyrophosphatase (AVP1) has been well studied and subsequently employed to improve salt and/or drought resistance in herbaceous plants. However, the exact function of H⁺-pyrophosphatase in woody plants still remains unknown. In this work, we cloned a homolog of type I H⁺-pyrophosphatase gene, designated as PtVP1.1, from Populus trichocarpa, and investigated its function in both Arabidopsis and poplar. The deduced translation product PtVP1.1 shares 89.74% identity with AVP1. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR analyses revealed a ubiquitous expression pattern of PtVP1.1 in various tissues, including roots, stems, leaves and shoot tips. Heterologous expression of PtVP1.1 rescued the retarded-root-growth phenotype of avp1, an Arabidopsis knock out mutant of AVP1, on low carbohydrate medium. Overexpression of PtVP1.1 in poplar (P. davidiana × P. bolleana) led to more vigorous growth of transgenic plants in the presence of 150 mM NaCl. Microsomal membrane vesicles derived from PtVP1.1 transgenic plants exhibited higher H⁺-pyrophosphatase hydrolytic activity than those from wild type (WT). Further studies indicated that the improved salt tolerance was associated with a decreased Na⁺ and increased K⁺ accumulation in the leaves of transgenic plants. Na⁺ efflux and H⁺ influx in the roots of transgenic plants were also significantly higher than those in the WT plants. All these results suggest that PtVP1.1 is a functional counterpart of AVP1 and can be genetically engineered for salt tolerance improvement in trees.

Within the genus Mycena, species exhibiting brownish basidiomata present considerable challenges in identification due to similar coloration. This study underscores the significance of pileipellis types and cheilocystidia characteristics as critical in delimiting brownish Mycena species. To clarify the principal taxonomic characters and their utility in distinguishing between brownish Mycena species, a morphological taxonomy and phylogenetic analysis were performed. Five new species from China were introduced and characterized through a comprehensive morphological anatomy and phylogenetic substantiation: M. campanulatihemisphaerica sp. nov., M. digitifurcata sp. nov., M. kunyuensis sp. nov., M. limitis sp. nov., and M. oryzifluens sp. nov. Discussions of these taxa are supplemented with morphological illustrations. The phylogenetic relationships were inferred using Bayesian Inference and Maximum Likelihood methods based on sequences from the internal transcribed spacer and the large subunit regions of nuclear ribosomal RNA. With the addition of these five new species, the worldwide count of brownish Mycena increases to 94, and a key to the 29 known species of brownish Mycena from China is presented.

Species of Mycena sect. Calodontes are representative of the Mycena genus as a whole and are easily recognised by the pinkish, reddish, purplish to brownish pileus and larger basidiomata. Furthermore, the colour of the pileus in the species of sect. Calodontes often has a transition or changes in different stages and the combination of the colour of the pileus with cystidia and basidiospores can be used to recognise taxa within this section. To date, 19 species of Mycena sect. Calodontes have been reported worldwide. Including our recent description of M. yuezhuoi, five species of sect. Calodontes have been recorded in China. During examination of specimens collected in coniferous forests or mixed broadleaf-conifer forests in temperate regions of China, additional taxa assigned to sect. Calodontes were identified. Four new species are recognised, based mostly on characters of the pileus and cystidia. Phylogenetic analysis of sequence data from multiple DNA regions (ITS + rpb1 + tef1) supported the morphological evidence. Here, we propose M. polycystidiata, M. rufobrunnea, M. shengshanensis and M. subulata as new species in Mycena sect. Calodontes. Morphological descriptions, line drawings, habitat photos and comparisons with closely-related taxa are provided. A key to the 23 known species of sect. Calodontes is presented.

During a study of Mycena s.l. in eastern China, a distinct species, Mycena yuezhuoi, was collected on the Jiaodong Peninsula. Mycena yuezhuoi has the following characteristics: a purple pileus, emarginate and white lamellae, elongated pip-shaped to cylindrical basidiospores, and cheilocystidia that are smooth or occasionally have an apical protrusion. The discovery of M. yuezhuoi provides new material for the study of Mycena sect. Calodontes, especially the M. pura complex. Although M. yuezhuoi closely resembles M. pura regarding macroscopic characteristics, it forms a monophyletic clade in phylogenetic trees that is distinct from clades in the M. pura complex. Moreover, the molecular phylogeny obtained from a combined analysis of multiple gene regions (ITS+RPB1+tEF1) supports the results of the morphological identification. We propose Mycena yuezhuoi as a new species based on morphological observations and phylogenetic analyses and provide line drawings, photos, descriptions, and comparisons with allied species.