Effects of plant community and altitude on food composition of Cervus elaphus wallichii during the withered grass period on the Tibetan Plateau, China.

How Tibetan red deer (Cervus elaphus wallichii) acclimates to high altitude environment during the withered grass period is one of the challenges in maintaining their nutrient intake. It is an important basis to study the nutritional ecology of wild large ungulates in alpine ecosystems by investigating the changes in plant communities with altitude during the withered grass period and how these changes affect the food composition of Tibetan red deer. In this study, we selected the Tibetan red deer in Sangri County, Shannan region of Tibet as the research subject. We carried out field surveys on the altitude, plant communities, and feeding traces of the Tibetan red deer in March of 2021 and 2022 during the withered grass period on the Tibetan Plateau. Detrended correspondence analysis and canonical correspondence analysis were used to study altitudinal variations in plant communities and the regularity of food composition. The results showed that during the period of withered grass, Tibetan red deer ate primarily Salix daltoniana, Rosa macrophylla var. glandulifera and Dasiphora parvifolia. S. daltoniana accounted for more than 50% of the food composition, as the main food resources for red deer in withered grass period. In the low altitude area (4100-4300 m), plant community included Caragana versicolor, R. macrophylla and Berberis temolaica, and Tibetan red deer mainly ate R. macrophylla, C. versicolor and Artemisia wellbyi. In higher altitude area (4300-4600 m), plant community consisted of Rhododendron nivale, Rhododendron fragariiflorum, and Sibiraea angustata, and Tibetan red deer mainly fed on S. daltoniana, Salix obscura, and Carex littledalei. At different altitudes, the dominant plant species were the main food of Tibetan red deer. It is suggested that the changes of plant community composition with altitude directly affected food composition of Tibetan red deer, indicating different food composition patterns with altitude gradients.

KNAT2/6b, a class I KNOX gene, impedes xylem differentiation by regulating NAC domain transcription factors in poplar.

Wood formation is the terminal differentiation of xylem mother cells derived from cambial initials, and negative regulators play important roles in xylem differentiation. The molecular mechanism of the negative regulator of xylem differentiation PagKNAT2/6b was investigated. PagKNAT2/6b is an ortholog of Arabidopsis KNAT2 and KNAT6 that is highly expressed in phloem and xylem. Compared to nontransgenic control plants, transgenic poplar plants overexpressing PagKNAT2/6b present with altered vascular patterns, characterized by decreased secondary xylem with thin cell walls containing less cellulose, xylose and lignin. RNA sequencing analyses revealed that differentially expressed genes are enriched in xylem differentiation and secondary wall synthesis functions. Expression of NAM/ATAF/CUC (NAC) domain genes including PagSND1-A1, PagSND1-A2, PagSND1-B2 and PagVND6-C1 is downregulated by PagKNAT2/6b, while PagXND1a is directly upregulated. Accordingly, the dominant repression form of PagKNAT2/6b leads to increased xylem width per stem diameter through downregulation of PagXND1a. PagKNAT2/6b can inhibit cell differentiation and secondary wall deposition during wood formation in poplar by modulating the expression of NAC domain transcription factors. Direct activation of PagXND1a by PagKNAT2/6b is a key node in the negative regulatory network of xylem differentiation by KNOXs.

Photocatalytic properties of a new Z-scheme system BaTiO3/In2S3 with a core-shell structure.

It's highly desired to design and fabricate an effective Z-scheme photo-catalyst with excellent charge transfer and separation, and a more negative conduction band edge (E CB) than O2/·O2 - (-0.33 eV) and a more positive valence band edge (E VB) than ·OH/OH- (+2.27 eV) which provides high-energy redox radicals. Herein, we firstly designed and synthesized a core-shell-heterojunction-structured Z-scheme system BaTiO3@In2S3 (BT@IS, labelled as BTIS) through a hydrothermal method, where commercial BT was used as the core and In(NO3)3·xH2O together with thioacetamide as the precursor of IS was utilized as the shell material. In this system, the shell IS possesses a E CB of -0.76 eV and visible-light-response E g of 1.92 eV, while the core BT possesses a E VB of 3.38 eV, which is well suited for a Z-scheme. It was found that the as-prepared BTIS possesses a higher photocatalytic degradation ability for methyl orange (MO) than commercial BT and the as-prepared IS fabricated by the same processing parameters as those of BTIS. Holes (h+) and superoxide radicals (·O2 -) were found to be the dominant active species for BTIS. In this work, the core-shell structure has inhibited the production of ·OH because the shell IS has shielded the OH- from h+. It is assumed that if the structure of BTIS is a composite, not a core-shell structure, ·OH could be produced during photocatalysis, and therefore a higher photocatalytic efficiency would be obtained. This current work opens a new pathway for designing Z-scheme photocatalysts and offers new insight into the Z-scheme mechanism for applications in the field of photocatalysis.

Growth-regulating factor 15 is required for leaf size control in Populus.

Growth-regulating factors (GRFs) are involved in various developmental events, particularly leaf development. However, the functions of GRFs in woody plants remain elusive. In this study, functional characterization of GRF15 in Populus was performed. Most GRFs are preferentially expressed in young leaves. As GRF15 was expressed at the highest level and with highest ratio in Populus species with large leaves, this gene was investigated through transgenic analyses. Promotor-ß-glucuronidase analysis revealed expression of GRF15 at the leaf expansion zone. Additionally, GRF15 was found to be localized in the nucleus and regulated by miR396. Leaf size and palisade cell size were significantly increased and decreased in GRF15-overexpressing and dominant repression lines, respectively. Consistently, expression of EXPA11a, a homolog of cell-expansion marker EXPA11 in Arabidopsis, was strongly upregulated and downregulated in the GRF15-overexpressing and dominant repression lines, respectively, which was further manifested by activation of EXPA11a by GRF15 in transactivation assays. Therefore, GRF15 is required for leaf size control and primarily modulates cell expansion during leaf development in Populus.