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It is of great importance to combine stress tolerance and plant quality for breeding research. In this study, the role of phytoene desaturase (PDS), z-carotene desaturase (ZDS) and carotene isomerase (CRTISO) in the carotenoid biosynthesis are correlated and compared. The three genes were derived from Lycium chinenses and involved in the desaturation of tetraterpene. Their over-expression significantly increased carotenoid accumulation and enhanced photosynthesis and salt tolerance in transgenic tobacco. Up-regulation of almost all the genes involved in the carotenoid biosynthesis pathway and only significant down-regulation of lycopene e-cyclase (e-LCY) gene were detected in those transgenic plants. Under salt stress, proline content, and activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) were significantly increased, whereas malonaldehyde (MDA) and hydrogen peroxide (H 2 O 2) accumulated less in the transgenic plants. The genes encoding ascorbate peroxidase (APX), CAT, POD, SOD, and pyrroline-5-carboxylate reductase (P5CR) were shown to responsive up-regulated significantly under the salt stress in the transgenic plants. This study indicated that LcPDS, LcZDS, and LcCRTISO have the potential to improve carotenoid content and salt tolerance in higher plant breeding.

As a novel family of 2D materials, MXenes have drawn intensive interests owing to its fascinating property profile. The ability to grow high‐quality MXenes in a controllable way would in turn further promote the development of fabrication techniques and expand wide advanced applications. Then 2D MXenes crystals are highly desirable and many approaches have been explored to realize the mass production. Chemical vapor deposition (CVD) provides compelling benefits over other alternatives in controllability, uniformity and scalability. In this review, the recent advances in growth of MXenes crystals by CVD method will comprehensively present. Several typical kinds of MXenes crystals are demonstrated to be fabricated with a precise control in terms of size, morphology and thickness. Further, a series of MXenes heterostructures are constructed including vertical and lateral spatial orientations. Then, the properties and applications of MXenes crystals are exhibited, of which superconductivity and electrochemical catalysts will be mainly emphasized. Finally, the authors put forward views on the future development in the synthesis of MXenes. With continuous efforts devoted, a bright future of MXenes crystals prepared by CVD is expected.

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benefits over other approaches, including mechanical exfoliation, epitaxial growth on SiC substrate, reduction of graphene oxides and molecular self-assembly. It has been widely recognized that the approach for scaled fabrication of 2D materials should have advantages both on quantities and quality for further advanced industrial uses. [8-10] In brief, CVD can make largescale and high-quality of 2D materials on a metal substrate at high temperature. The key point of the CVD approach lies in that it can realize fine control over nucleation and growth stages of 2D materials by purposely modulating CVD growth parameters. Currently, the reported size of single-crystal 2D materials has been reached up to meterscale, [11] paving the way toward industrial production and scaled applications. In the whole CVD growth process for 2D materials, there usually exist several para meters that can largely affect the final growth of materials, such as temperature, pressure, gas flow rate, catalyst and growth time and so on. Of all those parameters, the catalysts have been considered as the most important one for fabrication of large-sized and high-quality 2D materials. [12-14] Two reasons are recognized to support the viewpoint, both of which are highly related to the nucleation and growth stages of 2D crystals. Graphene growth on surface of catalysts is taken as an example. Large-scale and high-quality 2D materials have been an emerging and promising choice for use in modern chemistry and physics owing to their fascinating property profile. The past few years have witnessed inspiringly progressing development in controlled fabrication of large-sized and singlecrystal 2D materials. Among those production methods, chemical vapor deposition (CVD) has drawn the most attention because of its fine control over size and quality of 2D materials by modulating the growth conditions. Meanwhile, Cu has been widely accepted as the most popular catalyst due to its significant merit in growing monolayer 2D materials in the CVD process. Herein, very recent advances in preparing large-sized 2D single crystals on Cu substrates by CVD are presented. First, the unique features of Cu will be given in terms of ultralow precursor solubility and feasible surface engineering. Then, scaled growth of graphene and hexagonal boron nitride (h-BN) crystals on Cu substrates is demonstrated, wherein different kinds of Cu surfaces have been employed. Furthermore, the growth mechanism for the growth of 2D single crystals is exhibited, offering a guideline to elucidate the in-depth growth dynamics and kinetics. Finally, relevant issues for industrialscale mass production of 2D single crystals are discussed and a promising future is expected.

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