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Conifers exhibit a number of constitutive and induced mechanisms to defend against attack by pests and pathogens such as mountain pine beetle (Dendroctonus ponderosae Hopkins) and their fungal associates. Ecological studies have demonstrated that stressed trees are more susceptible to attack by mountain pine beetle than their healthy counterparts. In this study, we tested the hypothesis that water deficit affects constitutive and induced responses of mature lodgepole pine × jack pine hybrids (Pinus contorta Dougl. ex Loud. var. latifolia Engelm. ex S. Wats. × Pinus banksiana Lamb.) to inoculation with the mountain pine beetle fungal associate Grosmannia clavigera (Robinson-Jeffrey and Davidson) Zipfel, de Beer and Wingfield. The degree of stress induced by the imposed water-deficit treatment was sufficient to reduce photosynthesis. Grosmannia clavigera-induced lesions exhibited significantly reduced dimensions in water-deficit trees relative to well-watered trees at 5 weeks after inoculation. Treatment-associated cellular-level changes in secondary phloem were also observed. Quantitative RT-PCR was used to analyze transcript abundance profiles of 18 genes belonging to four families classically associated with biotic and abiotic stress responses: aquaporins (AQPs), dehydration-responsive element binding (DREB), terpene synthases (TPSs) and chitinases (CHIs). Transcript abundance profiles of a TIP2 AQP and a TINY-like DREB decreased significantly in fungus-inoculated trees, but not in response to water deficit. One TPS, Pcb(+)-3-carene synthase, and the Class II CHIs PcbCHI2.1 and PcbCHI2.2 showed increased expression under water-deficit conditions in the absence of fungal inoculation, while another TPS, Pcb(E)-β-farnesene synthase-like, and two CHIs, PcbCHI1.1 and PcbCHI4.1, showed attenuated expression under water-deficit conditions in the presence of fungal inoculation. The effects were observed both locally and systemically. These results demonstrate that both constitutive and induced carbon- and nitrogen-based defenses are affected by water deficit, suggesting potential consequences for mountain pine beetle dynamics, particularly in novel environments.

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Tree diversity in Asia's tropical and subtropical forests is central to nature-based solutions. Species vulnerability to multiple threats, which affect provision of ecosystem services, is poorly understood. We conducted a region-wide, spatially explicit assessment of the

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Vatica cauliflora P.S. Ashton (Dipterocarpaceae) is a threatened tree species endemic to Kapuas Hulu District, West Kalimantan Province, Indonesia. The species is only known from the type specimen collected in 1953. After this first collection, there was no record confirming the presence of this tree in its natural habitat. Our recent surveys in 2019 and 2020 located 179 individuals of the species in six unprotected locations. The population's size structure is dominated (62.6%) by young individuals within the 0–5 cm diameter class. Our surveys also showed that the habitat of V. cauliflora is degraded as a result of the negative effects of agriculture and logging. Assessment with the IUCN Red List criteria indicates that V. cauliflora should be categorized as Critically Endangered.

Societal Impact Statement Comprehensive Red List assessments act as valuable resources for informing protected area designations, national protected species legislation and action strategies, and international biodiversity agreements, yet they are lacking for many plant families. Magnoliaceae is one of the most comprehensively assessed families, as coordinated efforts have taken place since 2007 to assess all species in the family. Due to the many efforts to assess these species, comparisons of the assessments and ex situ data over time and an investigation of the most recent (2021) information are essential to guiding the development of national, regional, and global conservation strategies for Magnoliaceae species in a time of increased global collaboration between conservation organizations.