Drought and salinity are major factors limiting crop productivity worldwide. DREB (dehydration-responsive element-binding) transcription factors play important roles in plant stress response and have been identified in a wide variety of plants. Studies on DREB are focused on the A-1 (DREB1) and A-2 (DREB2) groups. Studies on A-5 group DREBs, which represent a large proportion of the DREB subfamily, is limited. In this study, we characterized and analyzed the stress tolerance function of ScDREB10, an A-5c type DREB gene from the desert moss Syntrichia caninervis. Transactivation assay in yeast showed that ScDREB10 had transactivation activity. Transient expression assay revealed that ScDREB10 was distributed both in the nucleus and cytosol of tobacco leaf epidermal cells. Overexpression of ScDREB10 significantly increased the germination percentage of Arabidopsis seeds under osmotic and salt stresses, and improved the osmotic and salt stress tolerances of Arabidopsis at the seedling stage and is associated with the expression of downstream stress-related genes and improved reactive oxygen species (ROS) scavenging ability. Our study provides insight into the molecular mechanism of stress tolerance of A-5 type DREB proteins, as well as providing a promising candidate gene for crop salt and drought stress breeding.

The whole‐plant activation of defense responses to wounding and herbivory requires systemic signaling in which jasmonates (JAs) play a pivotal role. To examine the nature of the slower cell‐nonautonomous as compared to the rapid cell‐autonomous signal in mediating systemic defenses in Nicotiana attenuata, reciprocal stem grafting‐experiments were used with plants silenced for the JA biosynthetic gene ALLENE OXIDE CYCLASE (irAOC) or plants transformed to create JA sinks by ectopically expressing Arabidopsis JA‐O‐methyltransferase (ovJMT). JA‐impaired irAOC plants were defective in the cell‐nonautonomous signaling pathway but not in JA transport. Conversely, ovJMT plants abrogated the production of a graft‐transmissible JA signal. Both genotypes displayed unaltered cell‐autonomous signaling. Defense responses (17‐hydroxygeranyllinalool diterpene glycosides, nicotine, and proteinase inhibitors) and metabolite profiles were differently induced in irAOC and ovJMT scions in response to graft‐transmissible signals from elicited wild type stocks. The performance of Manduca sexta larvae on the scions of different graft combinations was consistent with the patterns of systemic defense metabolite elicitations. Taken together, we conclude that JA and possibly MeJA, but not JA‐Ile, either directly functions as a long‐distance transmissible signal or indirectly interacts with long distance signal(s) to activate systemic defense responses.

Background: Wild apple, Malus sieversii, is an endangered species and a valuable genetic resource that requires a variety of conservation techniques. This study aimed to investigate the influence of different concentrations of hormones on wild apple regeneration from leaf and stem explants to establish an optimal regeneration system. Results: Leaves and stems derived from seedlings were cultured on several media supplemented with various concentrations of thidiazuron (TDZ) or 6-benzylaminopurine (BA) in different combinations with 1-naphthaleneacetic acid (NAA). The results showed that the most efficient shoot formation media (35% and 90%) were MS medium containing 4.0 mg L⁻¹ TDZ and 1.0 mg L⁻¹ NAA for leaf explants and MS medium containing 1.0 mg L⁻¹ BA without NAA for stem explant. MS medium supplemented with 0.4 mg L⁻¹ BA and 0.1 mg L⁻¹ NAA (for shoot multiplication) and 1/2 MS + 0.1 mg L⁻¹ NAA + 1.5% sucrose (for rooting) were effective media. Shoot regeneration from leaf explants was the most effective when the explants were placed abaxial side down onto the medium and were subjected to a pre-treatment of 3 weeks in darkness. Conclusions: An optimized regeneration system for M. sieversii that allowed regeneration within 2–3 months developed. The protocol developed herein can be used in large-scale clonal propagation for the conservation of wild apple, M. sieversii.

The genusAgriluscomprises diverse exotic and agriculturally important wood-boring insects that have evolved efficient digestive systems.Agrilus maliMatsumara, an invasive insect, is causing extensive mortality to endangered wild apple trees in Tianshan. In this study, we present an in-depth characterization of the gut microbiota ofA. malibased on high-throughput sequencing of the 16S rRNA gene and report the presence of lignocellulose-degrading bacteria. Thirty-nine operational taxonomic units (OTUs) were characterized from the larval gut. OTUs represented 6 phyla, 10 classes, 16 orders, 20 families, and 20 genera. The majority of bacterial OTUs belonged to the order Enterobacteriales which was the most abundant taxa in the larval gut. Cultivable bacteria revealed 9 OTUs that all belonged to Gammaproteobacteria. Subsequently, we examined the breakdown of plant cell-wall compounds by bacterial isolates. Among the isolates, the highest efficiency was observed inPantoeasp., which was able to synthesize four out of the six enzymes (cellulase, cellobiase, β-xylanase, and β-gluconase) responsible for plant-cell wall degradation. One isolate identified asPseudomonas orientalisexhibited lignin peroxidase activity. Our study provides the first characterization of the gut microbial diversity ofA. malilarvae and shows that some cultivable bacteria play a significant role in the digestive tracts of larvae by providing nutritional needs.