Genome assembly of autotetraploid Actinidia arguta highlights adaptive evolution and enables dissection of important economic traits.

Actinidia arguta, the most widely distributed Actinidia species and the second cultivated species in the genus, can be distinguished from the currently cultivated Actinidia chinensis on the basis of its small and smooth fruit, rapid softening, and excellent cold tolerance. Adaptive evolution of tetraploid Actinidia species and the genetic basis of their important agronomic traits are still unclear. Here, we generated a chromosome-scale genome assembly of an autotetraploid male A. arguta accession. The genome assembly was 2.77 Gb in length with a contig N50 of 9.97 Mb and was anchored onto 116 pseudo-chromosomes. Resequencing and clustering of 101 geographically representative accessions showed that they could be divided into two geographic groups, Southern and Northern, which first diverged 12.9 million years ago. A. arguta underwent two prominent expansions and one demographic bottleneck from the mid-Pleistocene climate transition to the late Pleistocene. Population genomics studies using paleoclimate data enabled us to discern the evolution of the species' adaptation to different historical environments. Three genes (AaCEL1, AaPME1, and AaDOF1) related to flesh softening were identified by multi-omics analysis, and their ability to accelerate flesh softening was verified through transient expression assays. A set of genes that characteristically regulate sexual dimorphism located on the sex chromosome (Chr3) or autosomal chromosomes showed biased expression during stamen or carpel development. This chromosome-level assembly of the autotetraploid A. arguta genome and the genes related to important agronomic traits will facilitate future functional genomics research and improvement of A. arguta.

A Risk Score System for Myopia Symptom Warning.

Myopia is the leading cause of visual impairments worldwide. Some studies revealed that visual experience in early life affected the final myopia, indicating that environmental factors play an impellent role in the development of myopia. However, risk factors of myopia are still not identified among adolescents in China. A total of 4104 cases of myopia symptom and 3306 emmetropia controls were selected from students in primary and middle schools in Wuhan in 2008. We identified the risk factors associated with myopia symptom by multivariate logistic regression in this cross-sectional study and constructed a risk score system for myopia symptom. The value of the area under the receiver operating characteristic curve (ROC) was 0.735. Furthermore, we followed up 93 students aged 7-9 years for one year and calculated the total points using the score system. We found no significant difference between the final myopia symptom and the results predicted by the total points by pair chi-square test (P>0.05). The score system had a modest ability to estimate the risk factors of myopia symptom. Using this score system, we could identify the students who are at risk of myopia symptom in the future according to their behaviors and environmental factors, and take measures to slow the progress of myopia symptom.

[Changes of non-structural carbohydrates and its impact factors in trees: a review].

Non-structural carbohydrates (NSCs) are an important energy source for the metabolism of plants. The size of the NSC pool is likely to mirror the overall carbon supply status and its dynamics strongly influences physiological processes in plants. In order to predict the response and adaptation of trees to climate change, this review summarized the current understanding of NSC pool in trees, and mainly focused on its seasonal and spatial variation for analyzing the relationships between environmental factors and NSC allocation. Moreover, the response and adaptation strategies of NSC pool in trees to climate change were also discussed. Finally, some suggestions were proposed for the potential study orientation of NSC pool in trees in future climate conditions.

[Obstacles for natural regeneration of Larix olgensis plantations in montane regions of eastern Liaoning Province, China].

Based on the field investigations about the seed bank, seed germination, seedling emergence, and seedling survival and growth in the Larix olgensis plantations with different thinning intensities and various ground preparations in the montane regions of eastern Liaoning Province, the main factors affecting the natural regeneration of L. olgensis were analyzed in this paper. The results showed that in the seed rain of 40 years old L. olgensis plantation, 30% of the seeds had viability, which could meet the needs of natural regeneration. The seeds in soil seed bank mainly distributed in litter layer, and the seedlings younger than one-year old emerged in April and reached the peak in June. The accumulative emergence rate of the seedlings had no significant correlation with thinning intensities, but was affected by ground preparations. The average survival rate of appeared seedlings increased with increasing thinning intensities, but the seedling growth was generally slow in the plantation stands, e.g., the seedling height was less than 6 cm, and most of the seedlings disappeared in September. In the plantation stands, it was difficult to find the L. olgensis seedlings elder than one-year; but in the clear-cut area with enough light and less ground cover, more seedlings could survive and grew well. Based on the above mentioned results, it was concluded that the main obstacles for the natural regeneration of L. olgensis plantations in montane regions of eastern Liaoning Province could be light intensity and ground cover.