A strain of Phoma species improves drought tolerance of Pinus tabulaeformis.

Global warming has led to frequent droughts, posing challenges for afforestation in arid and semiarid regions. In search of labor-saving and money-saving methods to improve the survival and growth rates of trees in these regions, we isolated and identified fungal endophytes that can potentially enhance the drought-resistance abilities of seedlings. We isolated 93 endophytic strains from the roots of Pinus tabulaeformis trees grown on an arid cliff. Three isolates increased the drought resistance of the tree seedlings. Using morphological, molecular, and physiological-biochemical methods, we identified three isolates as different clones of a strain of Phoma spp. and studied the strain's effect on stress resistance-related substances in the seedlings. The results showed that the strain improved drought tolerance and increased the seedlings' proline levels and antioxidant enzyme activities. The strain also secreted abundant extracellular abscisic acid, which likely triggered the seedlings' protective mechanisms. This endophytic strain may provide a cheaper labor-saving, sustainable alternative to traditional methods of enhancing drought resistance.

Distribution Dynamics and Roles of Starch in Non-photosynthetic Vegetative Organs of Santalum album Linn., a Hemiparasitic Tree.

Allocation dynamics of stored starch plays essential roles in the development and growth of trees. Previous studies focused on the dynamics and the characteristics of starch in autotrophic trees. However, although starch granules have been detected in the organs or tissues of some parasitic plants, studies on the allocation dynamics and roles of storage starch in them are limited. Therefore, we determined and estimated the allocation dynamics and roles of starch in Santalum album Linn., a hemiparasitic tree, using morphological and physiological methods. Our findings showed abundant starch in the stem and root of S. album at the early seedling stage. Although S. album seedlings attached to the host showed no significant changes in starch levels throughout the experiment, unattached and host-removed seedlings exhibited a gradual decrease in the starch content over time. When the starch content of unattached seedlings was less than 1%, they started to die. Starch accumulated to high levels in developing and active haustoria; however, starch levels were low in the inactive haustoria. The present study suggests that starch may provide energy to seedlings that have no host, allowing them to survive during the unattached phase, thus increasing their chance to attach to host roots by extending their survival duration. In addition, we speculate that storage starch is potentially involved in the development of haustoria and in the physiological processes of S. album related to the absorption and transportation of water and nutrients from its host.

Characterization of the complete chloroplast genome of Melampyrum roseum.

In this study, the complete chloroplast (cp) genome of Melampyrum roseum was determined through Illumina sequencing method. The complete cp genome of M. roseum was 143,896 bp in length and contained a pair of IR regions (25,210 bp) separated by a small single-copy region (10,292 bp) and a large single-copy region (83,184 bp). The cp genome of M. roseum encoded 117 genes including 78 protein-coding genes, 31 tRNA genes, and 8 rRNA genes. The overall GC content of M. roseum cp genome is 38.1%. By phylogenetic analysis using maximum-likelihood (ML) method, M. roseum was placed in Rhinantheae clade as expected.

Altered expression patterns of TCP and MYB genes relating to the floral developmental transition from initial zygomorphy to actinomorphy in Bournea (Gesneriaceae).

The shift from zygomorphy to actinomorphy has been intensively studied in molecular genetic model organisms. However, it is still a key challenge to explain the great morphological diversity of derived actinomorphy in angiosperms, since different underlying mechanisms may be responsible for similar external morphologies. Bournea (Gesneriaceae) is of particular interest in addressing this question, as it is a representative of primarily derived actinomorphy characteristic of a unique developmental transition from zygomorphy to actinomorphic flowers at anthesis. Using RNA in situ hybridization, the expression patterns were investigated of three different Bournea orthologues of TCP and MYB genes that have been shown to control floral symmetry in model species. Here, it is shown that the initial zygomorphic pattern in Bournea is likely a residual zygomorphy resulting from conserved expression of the adaxial (dorsal) identity gene BlCYC1. As a key novel event, the late downregulation of BlCYC1 and BlRAD and the correlative changes in the late specific expression of the abaxial (ventral) identity gene BlDIV should be responsible for the origin of the derived actinomorphy in Bournea. These results further indicate that there might be diverse pathways in the origin and evolution of derived actinomorphy through modifications of pre-existing zygomorphic developmental programs under dynamics of regulatory networks.

Two thymol derivatives from the flower buds of Lonicera japonica and their antibacterial activity.

A new monoterpenoid, 7-acetyl-8,9-dihydroxy thymol (1), together with a known one 7,8-dihydroxy-9-buyryl thymol (2), were isolated from the dried flower buds of Lonicera japonica Thunb. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analyses. The potential antibacterial effects of these compounds on Staphylococcus aureus, Escherichia coli, Micrococcus luteus, and Bacillus cereus were evaluated. Interestingly, both compounds 1 and 2 exhibited significant antibacterial activities with IC50 values range from 27.64 ± 2.26 to 128.58 ± 13.26 µg/mL.