Grafting is a widely used technique for asexual plant reproduction, especially in agriculture and forestry. This procedure is used to shorten the seedling period, improve the structure of scion branches, and help plants adapt to difficult environments. Although grafting has numerous benefits, several obstacles remain to be overcome. The connection between scion and rootstock is regulated by various factors, including phytohormones and molecular mechanisms, which are crucial for graft healing. This review provides an overview of recent advances in the field of grafting, with a specific focus on the factors and regulatory pathways that influence graft healing. The ultimate goal is to aid understanding of how to achieve successful grafting between plants and create desirable grafting chimeras. We provide an overview of the latest developments in plant grafting, covering aspects related to morphology, physiology, and molecular biology. We also discuss research directions in polyploid breeding and long-distance transfer of small molecules in grafted plants.

Sapindus mukorossi is a native tree in southern China that has multiple useful functions, including high landscaping, ecological, esthetic, and economic values. More importantly, its fruits are being rapidly developed as raw materials for bioenergy and saponin production in southern China. To provide a standardized phenological description of the species, this study firstly used the BBCH (Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie) scale. In total, eight principal stages—i.e., bud, leaf and shoot development, inflorescence emergence, flowering, fruit development, fruit maturity, senescence and beginning of dormancy—and 58 secondary stages were described. It ranges from vegetative bud dormancy to the onset of the next beginning of the dormancy, using a two-digit numerical coding system. In addition to the descriptions, we provide photographic images of some major developmental stages to standardize morphological characteristics and the phenological observation of S. mukorossi. This study will be an asset for biological researches and cultivation management in Sapindus, and will provide valuable information for other fruit trees.

The ecosystems across the Tibetan Plateau are changing rapidly in response to climate change, which poses unprecedented challenges for the control and mitigation of desertification on the Tibetan Plateau. Sophora moorcroftiana (Benth.) Baker is a drought-resistant plant species that has great potential to be used for desertification and soil degradation control on the Tibetan Plateau. In this study, using a maximum entropy (MaxEnt) niche model, we characterized the habitat distribution of S. moorcroftiana on the Tibetan Plateau under both current and future climate scenarios. To construct a robust model, 242 population occurrence records, gathered from our field surveys, historical data records, and a literature review, were used to calibrate the MaxEnt model. Our results showed that, under current environmental conditions, the habitat of S. moorcroftiana was concentrated in regions along the Yarlung Tsangpo, Lancang, and Jinsha rivers on the Tibetan Plateau. Elevation, isothermality, and minimal air temperature of the coldest month played a dominant role in determining the habitat distribution of S. moorcroftiana. Under future climate scenarios, the increased air temperature was likely to benefit the expansion of S. moorcroftiana over the short term, but, in the long run, continued warming may restrict the growth of S. moorcroftiana and lead to a contraction in its habitat. Importantly, the Yarlung Tsangpo River valley was found to be the core habitat of S. moorcroftiana, and this habitat moved westwards along the Yarlung Tsangpo River under future climate scenarios, but did not detach from it. This finding suggests that, with the current pace of climate change, an increase in efforts to protect and cultivate S. moorcroftiana is necessary and critical to control desertification on the Tibetan Plateau.

Summary: Sapindus is an important forest tree genus with utility in biodiesel, biomedicine, biochemistry and forestry. Similar to many perennial crop plants, its breeding is hampered by long generation times and lack of genetic resources. To understand the genome evolution underlying the important bioeconomic traits, we carried out a common garden experiment with 100 Sapindus core germplasm individuals representing three endemic species and 60 populations sampled throughout China. Whole genome sequencing identified a split into six populations according to species and geography. The previously uncharacterized S. delavayi and S. rarak are diploid species, and here we propose hypotheses for their speciation. Selective sweeps suggested stress responses as well as alleles of the genes CYP716A, CAMTA and HD‐ZIP involved in triterpenoid saponin biosynthesis to have been under selection in natural populations, while genome‐wide association analysis revealed several homologues of fatty acid biosynthesis genes to be associated with kernel fatty acid quality. Our findings elucidate the genetic structure of Sapindus in China, provide target loci for selection and suggest cultivar materials for genetic improvement.

Biodiesel has many advantages, yet its high price has become the main obstacle to market acceptance. Selecting non-edible woody oil plant resources and optimizing the oil extraction process will contribute to the effective utilization of raw materials and development of the related biodiesel industry. This study presents a detailed evaluation of two Sapindus species (Sapindus delavayi (Franch.) Radlk. and Sapindus mukorossi Gaertn.) as promising feedstocks for biodiesel production. As ultrasonic-assisted extraction (UAE) is considered a green and efficient oil extraction method, the process was optimized by response surface methodology (RSM) using a Box–Behnken design (BBD) in our study. The kernel oil yield of S. delavayi was up to 43.67% ± 0.16% under the optimized extraction conditions (the ultrasonic power was 109W, extracting at 65 °C for 25 min, and the liquid–solid ratio was 9 mL·g⁻¹). The kernel oil yield of S. mukorossi was as high as 45.96% ± 0.21% under the optimized extraction conditions (the ultrasonic power was 114W, extracting at 68 °C for 26 min, and the liquid–solid ratio was 9 mL·g⁻¹). The fatty acid profiles of S. delavayi and S. mukorossi kernel oils showed a high percentage of monounsaturated fatty acids (74.91% and 76.32%, respectively) and a low percentage of polyunsaturated fatty acids (11.11% and 7.83%, respectively) and saturated fatty acids (13.98% and 15.85%, respectively). Most of the properties of the two biodiesels conformed to EN 14214:2014, ASTM D6751–2018 and GB 25199–2017 standards, except for oxidation stability. In general, the results provided the optimized extraction method using ultrasound for the two species oil extraction and proved that the two kernel oils are potentially useful feedstocks for high-quality and low-cost biodiesel production.