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Sapindus mukorossi is an environmentally friendly plant and renewable energy source whose fruit has been widely used for biomedicine, biodiesel, and biological chemicals due to its richness in saponin and oil contents. Here, we report the first chromosome-scale genome assembly of S. mukorossi (covering ~391 Mb with a scaffold N50 of 24.66 Mb) and characterize its genetic architecture and evolution by resequencing 104 S. mukorossi accessions. Population genetic analyses showed that genetic diversity in the southwestern distribution area was relatively higher than that in the northeastern distribution area. Gene flow events indicated that southwest species may be the donor population for the distribution areas in China. Genome-wide selective sweep analysis showed that a large number of genes are involved in defense responses, growth and development, including SmRPS2, SmRPS4, SmRPS7, SmNAC2, SmNAC23, SmNAC102, SmWRKY6, SmWRKY26, and SmWRKY33. We also identified several candidate genes controlling six agronomic traits by genome-wide association studies, including SmPCBP2, SmbHLH1, SmCSLD1, SmPP2C, SmLRR-RKs, and SmAHP. Our study not only provides a rich genomic resource for further basic research on Sapindaceae woody trees but also identifies several economically significant genes for genomics-enabled improvements in molecular breeding.

Background Three dimensional speckle tracking echocardiography (3D STE) is a novel technique combining 3D echocardiography and speckle tracking analysis. 3D STE software dedicated to the left atrium (LA) was recently available. Our study aimed to assess (1) atrial fibrillation (AF) related LA morpho-functional remodeling using 3D STE and (2) value of LA function parameters in identifying paroxysmal AF (PAF). Methods One hundred thirty-nine PAF, 109 persistent AF (Per-AF) and 59 non-AF subjects underwent 3D STE. LA phasic volumes and total LA emptying fraction (LAEF) were obtained and used to calculate passive (pLAEF) and active LA emptying fraction (aLAEF) based on atrial contraction. LA longitudinal and circumferential strain representing reservoir (LASr/LASrc), conduit (LAScd/LAScdc) and pump (LASct/LASctc) function were also assessed. Results 3D STE was found to have good reproducibility. Increase of LA volumes and decrease of parameters representing LA reservoir and pump function were independently associated with AF as well as AF burden. The correlations between LA emptying fraction and LA circumferential strain representing the same function were always stronger than those with LA longitudinal strain (p 0.8) with great sensitivity and specificity. Conclusions Assessing LA remodeling in AF using 3D STE was feasible. AF and AF burden were independently associated with LA enlargement and impairment of reservoir and pump function but not conduit function. LA function parameters can indicate underlying PAF and thus can guide AF screening strategy.

The germination rate of conventional seed treatment for Acer fabri is relatively low. It is of great significance to study seed propagation methods to improve germination rate of A. fabri. The seeds of A. fabri should be harvested in November and stored in wet sand till February or March next year. Cool storage or room temperature storage is not conducive to the germination of A. fabri. After pregermination, the seeds can be sown in sandy soil and the germination rate could reach more than 70%. The cutting scions of A. fabri may not be processed, or may be treated by 100 PPM Indolebutyric acid on the scion base, and the rooting rate reached 94%, the average number of lateral roots per plant reached 3.6, and the average lateral root length reached 5.3 cm. Too many roots generated while the base of scions was treated with 1000 PPM or 2000 PPM Indolebutyric acid, and the plantlets grew slowly. A. fabri contains high endogenous hormone, so low concentration IBA or no growth regulator treatment is beneficial to root and later growth. The results provide practical mass production techniques for A. fabri.

The frequency and intensity of heat waves (HWs) has increased in subtropical regions in recent years. The mechanism underlying the HW response of subtropical trees remains unclear. In this study, we conducted an experiment with broad-leaved Schima superba (S. superba) and coniferous Cunninghamia lanceolata (C. lanceolata) seedlings to examine HW (5-day long) effects on stem water transport, leaf water use efficiency (WUE), morphology and growth, and to elucidate differences in the responses of both species. Our results indicated that HWs can significantly reduce hydraulic conductivity in both species. C. lanceolata experienced significant xylem embolism, with the percentage loss of conductivity (PLC) increasing by 40%, while S. superba showed a non-significant increase in PLC (+25%). Furthermore, HW also caused a reduction in photosynthesis rates (An), but transpiration rates (Tr) increased on the 5th day of the HW, together leading to a significant decrease in leaf WUE. From diurnal dynamics, we observed that the HW caused significant decrease of S. superba An only in the morning, but nearly the all day for C. lanceolata. During the morning, with a high vapor pressure deficit (VPD) environment, the HW increased Tr, which contributed a lot to latently cooling the foliage. In comparing the two tree species, we found that HW effects on S. superba were mostly short-term, with leaf senescence but limited or no xylem embolism. The surviving S. superba recovered rapidly, forming new branches and leaves, aided by their extensive root systems. For C. lanceolata, continued seedling growth initially but with subsequent xylem embolism and withering of shoots, led to stunted recovery and regrowth. In conclusion, apart from the direct thermal impacts caused by HW, drought stress was the main cause of significant negative effects on plant water transport and the photosynthetic system. Furthermore, S. superba and C. lanceolata showed clearly different responses to HW, which implies that the response mechanisms of broad-leaved and coniferous tree species to climate change can differ.

Tea tree oil is extracted from the leaves and twigs of Melaleuca alternifolia (Maiden & Betche) Cheel, and it is widely used in medicines, food preservatives, cosmetics and health care products. Traditional propagation of M. alternifolia from seeds does not necessarily transfer the desired characteristics from their mother trees, the seedlings are not uniform, and the multiplication rate from cuttings is relatively low. For these reasons, it is necessary to develop tissue culture techniques for this species. This study showed that an efficient explant initiation medium for M. alternifolia was MS 1/2 + BA 0.6 mg L−1 + NAA 0.1 mg L−1 + sucrose 30 g L−1, which yielded a 75.9 % initiation rate. An efficient multiplication medium was MS + BA 0.3 mg L−1 + NAA 0.15 mg L−1 + sucrose 30 g L−1, which yielded a 4.3 multiplication rate and 3.2 cm shoot length. The rooting medium was MS 1/2 + IBA 0.1–0.25 mg L−1 + sucrose 15 g L−1, which yielded a 100 % rooting rate, 2.94–3.32 roots per individual and 1.36–1.44 cm root length. Local red-core soil was suitable as a transplant medium, and yielded 98 % survival. This study improved the tissue culture technique for mass-propagation of M. alternifolia, enabling the production of high quality plants for market.

In breeding programs, the variations and relationships among main traits need to be understood to develop selection and breeding strategies. Resin is considered as one of most important non-timber production of P. massoniana which can privides terpenes used in the chemical industry. The present study assessed the genetic variations in growth, morphologic traits, and resin yield, as well as the phenotypic and genetic correlations between these traits of 45 half-sib families of eight-year-old Pinus massoniana trees. All traits show highly significant family effects. The individual heritability for diameter at breast height (DBH) was the highest (hi 2=0.55). Heritabilities for resin yield, tree height, crown depth, and the height to the live crown were slightly lower than DBH, ranging from 0.32 to 0.45. The other traits were under weak genetic control and heritabilities ranged from 0.17 to 0.20. All growth and morphologic traits were significantly correlated genetically with resin yield. Number of living branches had the highest genetic correlation with resin yield (rg=0.99), followed by DBH and number of living whorls (rg=0.73 and 0.70). Only a moderate positive genetic correlation with resin yield was found with the other traits (rg=0.47-0.57), except for height under the living branches (rg=-0.45). The results of this study indicate that both resin yield and growth can be improved simultaneously in the next generation. Of the traits assessed DBH was the optimum trait for indirectly selecting high-yielding resin trees.

Osmotin plays an important role in plant response to low temperature and pathogen infection . To date l ittle is known on existence and full function of OSM genes in genome-wide. I n this study, based on an OSM expression sequence tag identified from a drought-treated subtractive library, StOSMs in the potato genome were identified and characterized in response to a water deficit gradient. BLAST and bioinformatic analysis revealed that there are at least eleven StOSMs in the potato genome . Among eleven StOSMs ,eight StOSM mRNAs accumulated in leaf at the drought-lethal critical point (DLP ) were at least 4-fold higher than in the control. The peak StOSM- 8E mRNA accumulation was 49-fold higher than the control. Three StOSM mRNAs in leaf at DLP were 9.2-f old lower than in the control. This result of qRT-PCR quantification was identical with the FPKM values of all eleven StOSMs examined in the the Potato Genome Sequence database (PGSD) . In conclusion, water deficiency does induce the regulation of the expression of the eleven StOSMs. Either up or downregulated by water deficiency, StOSM s play a positive role in enhancing potato tolerance to drought stress. Therefore, osmotins can be considered to be drought responsive molecules involved in withstanding water deficits. The result provides an evidence to reveal how potato adapts to drought stress.

Fisher Linear Discriminant (FLD) is a well-known method for dimensionality reduction and classification that projects high-dimensional data onto a low-dimensional space where the data achieves maximum class separability. To improve the learning performance of FLD algorithm, in this paper we introduce Markov sampling algorithm to generate uniformly ergodic Markov chain samples from a given i.i.d. data of finite size by following the enlightening idea from MCMC methods. Through simulation studies and numerical studies on benchmark repository using FLD algorithm, we found that FLD algorithm based on uniformly ergodic Markov samples generated by the markov sampling algorithm introduced in this paper can provide smaller mean square error compared to the i.i.d. sampling from the same data.