A tandem array of ent-kaurene synthases in maize with roles in gibberellin and more specialized metabolism

While most commonly associated with its role in gibberellin (GA) phytohormone biosynthesis, ent-kaurene also serves as an intermediate in more specialized diterpenoid metabolism, as exemplified by the more than 800 known derived natural products. Among these are the maize kauralexins. However, no ent-kaurene synthases (KSs) have been identified from maize. The maize GA-deficient dwarf-5 (d5) mutant has been associated with a loss of KS activity. The relevant genetic lesion has been previously mapped, and was found here to correlate with the location of the KS-like gene ZmKSL3. Intriguingly, this forms part of a tandem array with two other terpene synthases (TPSs). Although one of these, ZmTPS1, has been previously reported to encode a sesquiterpene synthase, and both ZmTPS1 and that encoded by the third gene, ZmKSL5, have lost the N-terminal γ-domain prototypically associated with KS(L)s, all three genes fall within the KS(L) or TPS-e sub-family. Here it is reported that all three genes encode enzymes that are targeted to the plastid in planta, where diterpenoid biosynthesis is initiated, and which all readily catalyze the production of ent-kaurene. Consistent with the closer phylogenetic relationship of ZmKSL3 with previously identified KSs from cereals, only transcription of this gene is affected in d5 plants. On the other hand, the expression of all three of these genes is inducible, suggesting a role in more specialized metabolism, such as that of the kauralexins. Thus, these results clarify not only gibberellin phytohormone, but also diterpenoid phytoalexin biosynthesis in this important cereal crop plant

The Temporal and Spatial Evolution Characteristics of the Ecosystem Service Value and Conversion Rate in China’s Key State-Owned Forest Regions

To achieve a sustainable development path that harmonizes ecological and economic considerations, China has advocated the “two mountains” concept: “lucid waters and lush mountains are invaluable assets”. This idea posits that those who protect the environment can economically benefit by selling pristine landscapes and utilizing rich ecological resources. This paper use “the equivalence factor method” to calculate ecological benefits, introduces a technical measure—the conversion rate of ecosystem service value—and analyzes its temporal and spatial evolution from 2003 to 2020 in the operational areas of 87 state-owned forestry enterprises in Northeast China. The findings show: (1) a significant improvement in ecosystem-service quality, with its value increasing from 404.7 to 850.2 billion CNY between 2003 and 2020. The restoration of the ecological environment in China’s KSFR provides a foundation for economic and social development. (2) A decrease in the economic gains derived by operators from developing protected ecosystems, with the most significant decline observed in economic benefits generated from the supply product, including timber harvesting. However, the industrial structure in KSFR shifted from being dominated by timber production to diversified development, with non-timber forest resources becoming an important part of regional economic growth. (3) Significant potential for realizing the value of ecosystem services, evidenced by an increasing trend in the conversion rates of cultural, regulatory, and supporting services. These findings underscore the effectiveness of China’s natural forest protection and restoration policies in optimizing forest ecology and realizing the “two mountains” concept through appropriate market transactions and ecological compensation mechanisms

A tandem array of ent-kaurene synthases in maize with roles in gibberellin and more specialized metabolism

While most commonly associated with its role in gibberellin (GA) phytohormone biosynthesis, ent-kaurene also serves as an intermediate in more specialized diterpenoid metabolism, as exemplified by the more than 800 known derived natural products. Among these are the maize kauralexins. However, no ent-kaurene synthases (KSs) have been identified from maize. The maize GA-deficient dwarf-5 (d5) mutant has been associated with a loss of KS activity. The relevant genetic lesion has been previously mapped, and was found here to correlate with the location of the KS-like gene ZmKSL3. Intriguingly, this forms part of a tandem array with two other terpene synthases (TPSs). Although one of these, ZmTPS1, has been previously reported to encode a sesquiterpene synthase, and both ZmTPS1 and that encoded by the third gene, ZmKSL5, have lost the N-terminal γ-domain prototypically associated with KS(L)s, all three genes fall within the KS(L) or TPS-e sub-family. Here it is reported that all three genes encode enzymes that are targeted to the plastid in planta, where diterpenoid biosynthesis is initiated, and which all readily catalyze the production of ent-kaurene. Consistent with the closer phylogenetic relationship of ZmKSL3 with previously identified KSs from cereals, only transcription of this gene is affected in d5 plants. On the other hand, the expression of all three of these genes is inducible, suggesting a role in more specialized metabolism, such as that of the kauralexins. Thus, these results clarify not only gibberellin phytohormone, but also diterpenoid phytoalexin biosynthesis in this important cereal crop plant.This is a manuscript of an article published as A Tandem Array of ent-Kaurene Synthases in Maize with Roles in Gibberellin and More Specialized Metabolism. Jingye Fu, Fei Ren, Xuan Lu, Hongjie Mao, Meimei Xu, Jörg Degenhardt, Reuben J. Peters, Qiang Wang. Plant Physiology Feb 2016, 170 (2) 742-751, DOI: 10.1104/pp.15.01727. Posted with permission.</p

The Aggravation of Summertime Nocturnal Ozone Pollution in China and Its Potential Impact on the Trend of Nitrate Aerosols

Abstract Tropospheric ozone (O3) concentration continued to increase over past years, thereby becoming a growing environmental concern in China. Most studies have focused on the analysis of daily maximum 8‐hr O3 concentration, while there is still a dearth of investigations of nocturnal O3. Here, by analyzing the data of 1,313 sites from the China National Environmental Monitoring Center, we show a remarkable increase in the nocturnal O3 concentration during summertime of 2015–2019 in most regions of China, revealing an aggravation of nocturnal O3 pollution. Combining with a GeoDetector model and statistical analysis, we clarify that the aggravation of nocturnal O3 pollution is mainly caused by reduction in both ambient nitrogen dioxide (NO2) concentration and wet scavenging in recent years. We further reveal that the increasing O3 may have enhanced the nocturnal particulate nitrate (NO3−) formation through N2O5 heterogeneous hydrolysis, and thereby driving the variation and long‐term trend of nocturnal NO3−