New sights into lipid metabolism regulation by low temperature in harvested Torreya grandis nuts.

BACKGROUND: Torreya grandis, a large evergreen coniferous tree with oil-rich nuts, undergoes a crucial ripening stage after harvest that results in oil accumulation, finally giving rise to the nut that is edible in roasted form. To understand lipid metabolism in T. grandis nuts during the post-harvest ripening period, the effects of low temperature on lipid content, fatty acid composition, lipid biosynthesis and degradation were investigated. RESULTS: The lipid content increased during ripening at room temperature and a low temperature slowed down this increase. Linoleic acid content increased at low temperature, which was accompanied by an increase in the microsomal oleate desaturase (FAD2) activity and FAD2 expression. Furthermore, a low temperature attenuated lipid peroxidation as indicated by lower contents of malondialdehyde, hydroperoxide and total free fatty acid in T. grandis nuts during the ripening stage, as well as the down-regulation of gene expression of lipid degradation-related enzymes such as phospholipase D and lipoxygenases. CONCLUSION: The findings of the present study indicate that a low temperature increased polyunsaturated fatty acid contents by increasing FAD2 biosynthesis and decreasing lipid peroxidation, thereby improving the oil yield in T. grandis nuts during the post-harvest ripening period. © 2019 Society of Chemical Industry.

Origin of the Taxaceae aril: evolutionary implications of seed-cone teratologies in Pseudotaxus chienii.

Background and Aims: Fleshy structures that promote biotic dispersal by ingestion have evolved many times in seed plants. Within the yew family Taxaceae sensu lato (six genera, including Cephalotaxus), it remains controversial whether the characteristic fleshy structure surrounding the seed is interpreted as a novel outgrowth of the base of the ovule (i.e. an aril) or a fleshy seed coat that is entirely derived from the integument (i.e. a sarcotesta). This paper presents a detailed study of both wild-type and teratological seed cones of Pseudotaxus chienii, including morphology, anatomy and ontogeny. Methods: Wild-type and teratological seed cones were investigated with the classical paraffin technique and subsequent astrablue/safranin staining and scanning electron microscopy. Key Results: The wild-type seed cone of Pseudotaxus possesses a fleshy white aril that is cup-like and not entirely fused to the seed. In the teratological seed cones investigated, the aril was bilobed and consisted of two free halves. In both wild-type and teratological cones, the aril was initiated as two lateral primordia in a transverse plane, but in wild-type cones the two primordia became extended into a ring primordium, which grew apically, leading to the cup-like shape. The teratological seed cones lacked a ring primordium and the two lateral aril lobes remained free throughout their entire ontogeny, alternating with the scale-like leaves inserted below them on the same branch; in some cases, these leaves also became fleshy. Conclusions: Based on the ontogeny and arrangement of the two fleshy aril lobes in the teratological seed cones of Pseudotaxus, we suggest that the typical aril of Taxaceae could be readily interpreted as a fused pair of strongly swollen leaves rather than a modified integument. Our investigations of the cup-like aril of Pseudotaxus demonstrate a similarity not only with other Taxaceae but also with relatively distantly related conifers such as Phyllocladus (Podocarpaceae).

[Microbial biodiversity in rhizospheric soil of Torreya grandis 'Merrillii' relative to cultivation history]. / ä¸åŒç§æ¤å¹´é™é¦™æ¦§æ ¹é™ åœŸå£¤å¾®ç”Ÿç‰©å¤šæ ·æ€§.

To examine the effects of different cultivation history (5 a,10 a, and 15 a) on soil microbial communities, we used Illumina sequencing to investigate the diversity and structure of soil bacterial and fungal communities from Torreya grandis 'Merrillii' fields. The results showed that bacterial Shannon index, the richness estimators Chao1 and ACE were lower in soil in 15 year-old stand than those in other cultivation histories, while Simpson index showed no significant variation. Results from bacterial community NMDS showed that cultivation history played a vital role in driving the changes of soil bacteria communitiy structure. The bacterial communities in 5 and 10 year-old stand had the similar composition. The variations of bacterial richness and diversity as well as community structure (comprised basically of Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi) were significantly correlated with soil organic matters, soil C/N, and total nitrogen. The fungi richness estimators of Chao1 and ACE were significantly decreased with increasing cultivation history. Shannon and Simpson indices were significantly higher in soil with 10 year-old stand than soils with other cultivation history. Fungal NMDS could be clustered in the same era. Fungal communities were comprosed of Ascomycota, Basidiomycota and Zygomycota. Changes in fungal richness/diversity and community structure were mainly controlled by the variation of soil organic matter. In conclusion, the predominant factors affecting soil microbial communities were the cultivation history, soil C/N, total nitrogen and organic matter, respectively.

Genetic linkage map construction and QTL identification of juvenile growth traits in Torreya grandis.

Torreya grandis Fort. ex Lindl, a conifer species widely distributed in Southeastern China, is of high economic value by producing edible, nutrient seeds. However, knowledge about the genome structure and organization of this species is poorly understood, thereby limiting the effective use of its gene resources. Here, we report on a first genetic linkage map for Torreya grandis using 96 progeny randomly chosen from a half-sib family of a commercially cultivated variety of this species, Torreya grandis Fort. ex Lindl cv. Merrillii. The map contains 262 molecular markers, i.e., 75 random amplified polymorphic DNAs (RAPD), 119 inter-simple sequence repeats (ISSR) and 62 amplified fragments length polymorphisms (AFLP), and spans a total of 7,139.9 cM, separated by 10 linkage groups. The linkage map was used to map quantitative trait loci (QTLs) associated with juvenile growth traits by functional mapping. We identified four basal diameter-related QTLs on linkage groups 1, 5 and 9; four height-related QTLs on linkage groups 1, 2, 5 and 8. It was observed that the genetic effects of QTLs on growth traits vary with age, suggesting the dynamic behavior of growth QTLs. Part of the QTLs was found to display a pleiotropic effect on basal diameter growth and height growth.

[Genetic diversity of natural and planted Glyptostrobus pensilis populations: a comparative study].

Glyptostrobus pensilis is a rare and endangered relict species in China. To make a comparative study on the genetic diversity and genetic structure of natural and planted G. pensilis populations would have significance in the conservation and proliferation of the species. Samples from the main distribution regions of G. pensilis were analyzed by ISSR (inter simple sequence repeats) molecular marker. A total of 95 discernible DNA fragments were detected with 10 ISSR primers, of which, polymorphic loci occupied 39.0%, suggesting that the genetic variation in the test G. pensilis populations was at a very low level, compared with other endangered gymnosperm. The genetic differential index (G(st) = 0.3982) and the gene flow (N(m) = 0.3778) indicated that there existed genetic differentiation among populations but the differentiation dominated within populations. There was a significant positive correlation between genetic distance and geographical distance. The mean values of polymorphic loci (P), Nei's gene index (H(e)), and Shannon information index (I) of natural populations (P = 39.9%, H(e) = 0.1499, I = 0.2202) were much higher than those of planted G. pensilis populations (P = 30.7%, H(e) = 0.1265, I = 0.1759), and the coefficient of gene differentiation (G(st)) and genetic distance (D) of natural populations (G(st) = 0.4513, D = 0.0301) were also much higher than those of the planted populations (G(st) = 0.3025, D = 0.0192).

[Genetic diversity of endangered plant Torreya jackii: a study with RAPD markers].

With random amplified polymorphic DNA (RAPD) techniques, this paper studied the genetic diversity and genetic differentiation of Torreya jackii, an endangered plant endemic to China. In the 180 individuals of 9 T. jackii natural populations, 180 repetitive loci were detected by using 12 random primers, among which, 119 were polymorphic. At species level, the percentage of polymorphic loci (P) was 66.11%, and the genetic diversity estimated by Shannon information index (I) and Nei's index (h) was 0.3087 and 0.2015, respectively, suggesting that the genetic diversity at species level was relatively high. However, at population level, the genetic diversity was relatively low (P = 23.76% , I = 0.1221, and h = 0.0813). The analysis of molecular variance (AMOVA) showed that 42.57% of genetic variance was found within populations, and 57.43% of it was resided among populations. The coefficient of gene differentiation (G(st)) was 0.5965, indicating the high genetic differentiation among the populations of T. jackii, and the gene flow among the populations was quite low, being 0.3382. The bottleneck effect, population isolation, and low gene flow among populations would have contributed to such a population genetic structure in T. jackii. The averaged genetic distance among 9 T. jackii populations was 0.1630. By using the unweighted pair group method with arithmetic mean (UPGMA), the 9 populations could be divided into two groups, i. e., Zhejiang group and Fujian group. It was proposed that in the ex situ conservation of T. jackii, the gcrmplasm transferring among populations should be avoided.

[Population structure and community characteristics of Pseudotaxus chienii in Fengyangshan National Natural Reserve].

Pseudotaxus chienii, an endemic plant in China, is one of the second grade state protection wild plants, and distributes in Fengyangshan Natural Reserve as one of its concentrative dwelling places. A survey in the region was carried out on 10 communities, which were dominated by P. chienii. The analysis on its size structure, spatial distribution pattern and community characteristics showed that the populations of P. chienii could grow in the communities dominated by Rhododendron simiarum, Fokienia hodginsii-R. simiarum, and evergreen broad-leaved forests. In R. simiarum communities, the size structure, survival curve, and overwhelming community distribution pattern of P. chienii showed a sustaining development, while in communities dominated by F. hodginsii-R. simiarum, though the size structure was declining, the survival curve was Deevy- III type. Plenty of plantlets were still existed, and the populations kept steady. Two types were considered to be the most suitable ones for P. chienii populations. The important value of P. chienii reached 5% - 10%. In evergreen broad-leaved forests, the populations of P. chienii showed to be a declining type, and the survival curve was Deevy- II type. The distribution pattern was random, indicating that P. chienii populations could not fit for survive in this kind of communities. Correlation analysis showed that P. chienii populations had a positive correlation with R. simiarum and F. hodginsii, but a negative correlation with Cyclobalanopsis stewardiana and Schima superba. P. chienii could associate to the habits with the community canopy density of about 0.6 - 0.8. From the results mentioned above, the populations of P. chienii could be able to sustain and develop, and the existing habitat in Fengyangshan should be protected effectively. The protection of P. chienii requires more basic work to establish efficient measures to protect its habitat.