Journal of Plant Biology最新文献

Extreme environmental stress significantly impacts plant growth. Drought stress is one of the most important abiotic stresses, adversely affecting plant development and agricultural productivity. Prunus mira is an exceptionally drought-tolerant plant. However, there are a limited number studies on the drought resistance of it. Here, we isolated and identified nascent polypeptide-associated complex subunit alpha-like protein 1 of P. mira (PmNACA1). PmNACA1 comprises 201 amino acids and contains an NAC domain at its N-terminal. It was localized in the cytoplasm and nucleus. PmNACA1 was primarily expressed in leaves, and was induced by drought. PmNACA1 overexpression Arabidopsis thaliana increased germination and root elongation. Histochemical staining revealed that the overexpression lines accumulated less ROS under mannitol-induced osmotic stress. Under drought stress, overexpression lines exhibited an elevation in the activities of SOD, POD, CAT, and GR and a rise in the levels of GSH and GSSG. In addition, the overexpression lines exhibited relatively lower levels of H₂O₂, O₂^.−, MDA, and electrical conductivity than control plants. PmNACA1 induced the expression of drought- and ABA-related genes after drought treatment. PmNACA1 scavenged H₂O₂, DPPH radicals, and hydroxyl radicals in vitro. In summary, we conclude that PmNACA1 plays an active role in drought stress response by scavenging ROS.

Abstract

Although climate change-related concerns have long been raised regarding the sudden dieback of Korean fir (Abies koreana), the event’s etiology and subsequent ecosystem processes must be explained. Our study aims to clarify the continuity or transience of mass mortality events within the coarse woody debris (CWD) structure and, if transient, to identify the climatic conditions (1974–2021) that could be responsible for the massive dying phenomena in Korean fir populations. On average, precipitation during the non-growing season (November–April as winter) constituted 18.5% relative to the growth period; in the winter of 1999, it was 4.8% due to an abnormal drought event. The dead stems occurred evenly across all size classes. In the CWD structure, the density and biomass of the dead fir individuals peaked in decay classes II or III. The size distribution of the retained fir was inverse-J shaped across the entire altitudinal range. The abnormal winter drought event, causing root damage by soil frost and heaving, may be one of the factors that increased Korean fir mortality across the entire stem size range. Despite transient cohort senescence, the retained Korean fir individuals transmitted drought-resistant traits into the regional pool following the drought event.

Cryptomeria japonica D. Don is a model plant for studying male sterility in conifers. To date, five male sterile loci have been identified by crossing tests. When at least one of these loci is homozygote of a recessive male sterile allele, male sterility is induced. Cytological studies have been performed for ms1 to ms4 mutants, but there have yet to be such investigations of ms5 mutants. This study newly showed that ms2 mutants lack callose and exhibit different phenotypes for each microsporangium. Furthermore, we found the leakage of cellular contents and the appearance of amorphous substances in ms3 mutants. We also detected leakage of cellular contents in ms4 mutants. On the other hand, abnormal pollen development in ms5 mutants was found to begin at the tetrad stage. This abnormality was characterized by the maintenance of abnormal tetrads and uneven spores, abnormal pollen wall formation, covered with amorphous substances, disappearance of the nucleus, and central nuclear positioning during the binuclear microspore stage. These results were clearly different from those of ms1 to ms4 mutants. Abnormal meiosis in pollen mother cells, the abnormal pollen wall, and abnormal mitosis during pollen development may be closely associated with male sterility caused by mutation of MS5.

Abstract

The succession process in terms of species composition and stand structure was directly tracked for 10 years in permanent plots of five Korean cool-temperate forests having different stand ages and topography: Pinus-Quercus forest (PQ), Quercus-Tilia forest (QT), Broadleaved-Abies mixed forest (BA), Populus-Salix forest (PS), and subalpine forest (SA). Although the 10-year change in mature forests was small, succession was detected by applying the pre-developed climax index. The species composition based on the climax index implied that PQ is at pioneer stage, QT and PS are at intermediate stage, while BA and SA are at the late-successional stage. The stems were regulated in a density-dependent manner; severer in forests such as PQ and QT with high initial densities, and severer in the dense mid-story than in the upper-story. Consequently, the basal area increased in the upper-story and decreased in the mid-story. As the abundance of species with higher climax index increased, succession exhibited a progressive direction. However, SA suffered chronic disturbances, and showed fluctuations. During the study, BA and PS were also damaged but they were resilient to site-related natural disturbances. Our findings through a 10-year permanent-plot study may have meaningful implications for explaining mature forest succession in other regions of Korea.

Abstract

Angiosperms proliferate through double fertilization mediated by male (pollen) and female (embryo sac) gametophytes. To determine the genes essential for pollen development in Arabidopsis thaliana, we first generated a mutant population using an activation tagging vector with herbicide-resistance gene and screened mature pollen phenotypes. Then, a T-DNA insertional heterozygous line was isolated, initially named AP22-48, which produced high levels of abnormal pollen grains. Reciprocal crosses revealed that the genetic transmission of the mutant allele was completely blocked through the male and was highly limited through the female. Determination of T-DNA flanking sequences and genetic complementation of AP22-48 identified AtCOG8, a subunit of the Conserved Oligomeric Golgi (COG) complex, which is a tethering factor essential for the Golgi architecture and retrograde vesicle trafficking in eukaryotes. We renamed the mutant atcog8-2, with reference to a previous cog8 mutant (atcog8-1). While atcog8-1 induced male-specific defects during pollen tube growth, atcog8-2 mutant failed to produce normal gametophytes in both sexes. Detailed morphological analysis demonstrated aberrant development of the pollen and embryo sac in atcog8-2 mutants. This study, thus, strongly suggests that the COG complex functions are broad and indispensable for accurate gametophyte development, which is a prerequisite for sexual reproduction in Arabidopsis.

Waterlogging stress is the most frequent abiotic factor affecting the agricultural productivity of major crop species. Profiling of the waterlogging response-related transcriptome of Keumkang, a domestic wheat cultivar cultivated mainly in South Korea, has not yet been conducted, despite advancing research in this field. Based on RNA sequencing (RNA-seq), we performed a comparative transcriptome analysis of cv. Keumkang seedlings subjected to waterlogging stress for up to 24 h. Comparative analysis revealed that waterlogging treatment increased the expression levels of most representative transcripts, including those of ethylene biosynthesis or activated signaling pathways, Ca²⁺ signaling pathways, and lignin biosynthetic pathways, suggesting that increased transcription of these genes under waterlogging conditions leads to the formation of aerenchyma and a radial oxygen loss barrier in wheat roots. Genes involved in anaerobic respiration and nitrate assimilation or reduction showed upregulated expression under waterlogging conditions compared to those under normal conditions, suggesting that waterlogging stress affects carbohydrate and nitrogen metabolism in wheat roots. The expression of randomly selected genes was evaluated using real-time quantitative PCR to validate the reliability of our RNA-seq results. The potential waterlogging stress-related transcripts identified herein are candidate genes for molecular studies of the adaptability of cv. Keumkang waterlogged stress.

Abscisic acid-, stress-, and ripening-induced (ASR) proteins are involved in response to abiotic stresses. However, the precise role of Brachypodium ASR genes in enhancing tolerance under drought stress conditions remains to be determined. In this study, we characterized the BdASR5 gene and determined that it has a function in drought stress tolerance. Overexpression of BdASR5 confers tolerance to drought stress in Brachypodium. Overexpression of BdASR5 resulted in higher relative water content and chlorophyll content, and lower ion leakage than WT plants under drought stress conditions. Moreover, overexpression of BdASR5 displayed increased antioxidant enzyme activity and upregulated expression of ROS-related, stress-related, and ABA-dependent pathway genes under drought stress condition. In addition, overexpression of BdASR5 showed hypersensitive to exogenous ABA at the germination stage. Moreover, overexpression of BdASR5 showed increased stomatal closure and decreased stomata conductance under ABA conditions. Collectively, these results suggest that BdASR5 functions as a positive regulator in response to drought stress.