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Climate change and the exploration of new areas of cultivation have impacted the yields of several economically important crops worldwide. Both conventional plant breeding based on planned crosses between parents with specific traits and genetic engineering to develop new biotechnological tools (NBTs) have allowed the development of elite cultivars with new features of agronomic interest. The use of these NBTs in the search for agricultural solutions has gained prominence in recent years due to their rapid generation of elite cultivars that meet the needs of crop producers, and the efficiency of these NBTs is closely related to the optimization or best use of their elements. Currently, several genetic engineering techniques are used in synthetic biotechnology to successfully improve desirable traits or remove undesirable traits in crops. However, the features, drawbacks, and advantages of each technique are still not well understood, and thus, these methods have not been fully exploited. Here, we provide a brief overview of the plant genetic engineering platforms that have been used for proof of concept and agronomic trait improvement, review the major elements and processes of synthetic biotechnology, and, finally, present the major NBTs used to improve agronomic traits in socioeconomically important crops.

Meloidogyne incognita is the most economically important species of root-knot nematodes (RKN) and causes severe damage to crops worldwide. M. incognita secretes several effector proteins to suppress the host plant defense response, and manipulate the plant cell cycle and other plant processes facilitating its parasitism. Different secreted effector proteins have already been identified in M. incognita, but not all have been characterized or have had the confirmation of their involvement in nematode parasitism in their host plants. Herein, we characterized the Minc03328 (Minc3s00020g01299) effector gene, confirmed its higher expression in the early stages of M. incognita parasitism in plants, as well as the accumulation of the Minc03328 effector protein in subventral glands and its secretion. We also discuss the potential for simultaneous downregulation of its paralogue Minc3s00083g03984 gene. Using the in planta RNA interference strategy, Arabidopsis thaliana plants overexpressing double-stranded RNA (dsRNA) were generated to specifically targeting and downregulating the Minc03328 gene during nematode parasitism. Transgenic Minc03328-dsRNA lines that significantly downregulated Minc03328 gene expression during M. incognita parasitism were significantly less susceptible. The number of galls, egg masses, and [galls/egg masses] ratio were reduced in these transgenic lines by up to 85%, 90%, and 87%, respectively. Transgenic Minc03328-dsRNA lines showed the presence of fewer and smaller galls, indicating that parasitism was hindered. Overall, data herein strongly suggest that Minc03328 effector protein is important for M. incognita parasitism establishment. As well, the in planta Minc03328-dsRNA strategy demonstrated high biotechnological potential for developing crop species that could efficiently control RKN in the field.

Transcriptional promoters are among the primary genetic engineering elements used to control genes of interest (GOIs) associated with agronomic traits. Cotton uceA1.7 was previously characterized as a constitutive promoter with activity higher than that of the constitutive promoter from the Cauliflower mosaic virus (CaMV) 35S gene in various plant tissues. In this study, we generated Arabidopsis thaliana homozygous events stably overexpressing the gfp reporter gene driven by different modules of the uceA1.7 promoter. The expression level of the reporter gene in different plant tissues and the transcriptional stability of these modules was determined compared to its full-length promoter and the 35S promoter. The full-length uceA1.7 promoter exhibited higher activity in different plant tissues compared to the 35S promoter. Two modules of the promoter produced a low and unstable transcription level compared to the other promoters. The other two modules rich in cis-regulatory elements showed similar activity levels to full-length uceA1.7 and 35S promoters but were less stable. This result suggests the location of a minimal portion of the promoter that is required to initiate transcription properly (the core promoter). Additionally, the full-length uceA1.7 promoter containing the 5′-untranslated region (UTR) is essential for higher transcriptional stability in various plant tissues. These findings confirm the potential use of the full-length uceA1.7 promoter for the development of new biotechnological tools (NBTs) to achieve higher expression levels of GOIs in, for example, the root or flower bud for the efficient control of phytonematodes and pest-insects, respectively, in important crops.

Wucai (Brassica campestris L. ssp. chinensis var. rosularis Tsen) is a subspecies of Brassica campestris, is a kind of cold-tolerant vegetable widely cultivated in the Yangtze-Huai River Basin of China. To breed new varieties of resistance to stress, it is necessary to study the tolerance of Resistance to different stresses. Transcriptomic data showed that exogenous application of 2, 4-epbrassinolide (EBR) significantly increased the bHLH genes expression in wucai at low temperature, and bHLH57 was up regulated significantly. BHLH (Basic helix-loop-helix) TFs (transcription factor) is a superfamily of TFs with complex functions and related to various plant life activities. In this study, a total of 239 bHLH genes were identified, and their amino acid physicochemical properties, chromosome location, gene structure, phylogeny and cis-acting elements were analyzed by bioinformatics. Phylogenetic analysis showed that bHLH gene families in Brassica rapa and Arabidopsis were divided into six groups, and the distribution of bHLH genes in Brassica rapa was uneven. The BrbHLHs were irregularly mapped in the cultivated B. rapa genome. The maximum number (40) of BrbHLH genes were mapped on Chr09. In addition, there were tandem repeats in some genes. The collinearity analysis showed that 152 AtbHLH genes and 239 BrbHLH protein genes formed 296 collinearity pairs, and the Ka/Ks ratio ofall duplicated BrbHLH gene pairs had a Ka/Ks ratio of < < 1, indicating that the bHLH family genes may have undergone strong purification and selection during the evolution process. Cis-acting elements analysis showed that the promoter region of bHLH family genes in Brassica rapa had more responsive elements related to light, hormone and abiotic stress. The BcbHLH57 overexpressing Arabidopsis thaliana lines were subjected to different stress treatments, and the seed germination rate, root growth, survival rate and various plant physiological indexes were determined. The results showed that the transgenic lines were more tolerant to salt, heat and drought stress. In this study, the response of BcbHLH57 gene to salt, heat and drought stress was reported for the first time, which provided a basis for further research on the function of BcbHLH57 in abiotic stress.Key messageBcbHLH57 overexpressing Arabidopsis thaliana lines showed strong tolerance to salt, heat and drought stress, which provided a basis for further research on the function of BcbHLH57 in abiotic stress.