Ancient association with Fagaceae in the aphid tribe Greenideini (Hemiptera: Aphididae: Greenideinae)

Aphids are intimately associated with their host plants. Evolutionary lability of host association is common within heteroecious aphid lineages, whereas our knowledge of host‐use evolution in non‐host‐alternating aphids is limited. In the present study, we construct the first detailed molecular phylogeny of the monoecious aphid tribe Greenideini based on three mitochondrial genes (COI, COII and Cytb) and one nuclear gene (EF‐1α), and investigated its history of host association. Maximum likelihood and Bayesian phylogenies strongly support the monophyly of Greenideini and most constituent genera. Divergence time estimates and character reconstructions suggest that Greenideini may have originated during the Late Cretaceous to early Paleogene, which accompanies the origin of its ancestral host, members of the family Fagaceae. Colonisation of novel host plants has occurred multiple times during the evolutionary history of Greenideini, thereby leading to current patterns of host association. We suggest that directly shifting to novel hosts, together with expanding host range onto pre‐existing, unused plants, has probably promoted diversification in this tribe.     

Identification of quantitative trait loci and a candidate locus for freezing tolerance in controlled and outdoor environments in the overwintering crucifer Boechera stricta

Development of chilling and freezing tolerance is complex and can be affected by photoperiod, temperature and photosynthetic performance; however, there has been limited research on the interaction of these three factors. We evaluated 108 recombinant inbred lines of Boechera stricta, derived from a cross between lines originating from Montana and Colorado, under controlled long day (LD), short‐day (SD) and in an outdoor environment (OE). We measured maximum quantum yield of photosystem II, lethal temperature for 50% survival and electrolyte leakage of leaves. Our results revealed significant variation for chilling and freezing tolerance and photosynthetic performance in different environments. Using both single‐ and multi‐trait analyses, three main‐effect quantitative trait loci (QTL) were identified. QTL on linkage group (LG)3 were SD specific, whereas QTL on LG4 were found under both LD and SD. Under all conditions, QTL on LG7 were identified, but were particularly predictive for the outdoor experiment. The co‐localization of photosynthetic performance and freezing tolerance effects supports these traits being co‐regulated. Finally, the major QTL on LG7 is syntenic to the Arabidopsis C‐repeat binding factor locus, known regulators of chilling and freezing responses in Arabidopsis thaliana and other species.     

气候变化背景下橡胶树物候研究进展

橡胶树(Heveabrasiliensis)是广布于热带地区的经济林木，是战略物资天然橡胶的主要来源，其物候学的研究对胶园生产管理和评估热带地区植被对全球气候变化的响应方面具有重要意义。早期的物候研究主要服务于苗木繁育、割胶规划和抗逆栽培等生产应用；利用遥感监测植被物候日趋成熟，已广泛应用于橡胶树并成为主流的物候监测方法；橡胶树物候具有明显的时空异质性，对气候变化的响应较为复杂，其中温度和降水是关键影响因子，同时内因(品系、基因和树龄等)和外因(种植密度、地理位置和农业措施等)也共同影响了其物候。为更好服务天然橡胶产业的可持续发展和热区气候变化科学研究，未来的橡胶树物候研究应重点关注多源遥感数据的协同重建、物候指标提取算法的普适化和遥感预测模型的精准化。该文系统梳理了橡胶树物候的监测方法、服务价值、时空格局，提出了存在问题及未来研究方向。