Minc03328 effector gene downregulation severely affects Meloidogyne incognita parasitism in transgenic Arabidopsis thaliana.

MAIN CONCLUSION: Minc03328 effector gene downregulation triggered by in planta RNAi strategy strongly reduced plant susceptibility to Meloidogyne incognita and suggests that Minc03328 gene is a promising target for the development of genetically engineered crops to improve plant tolerance to M. incognita. 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.

Genetic Approaches for Iron and Zinc Biofortification and Arsenic Decrease in Oryza sativa L. Grains.

Rice is the staple diet to half of the world's population, being a major source of carbohydrates, vitamins, and some essential elements. However, rice naturally contains low amounts of essential minerals such as iron (Fe) and zinc (Zn), which are drastically decreased after milling. Thus, populations that consume mostly rice may have micronutrient deficiency, which is associated with different diseases. On the other hand, rice irrigated by flooding has a high ability to accumulate arsenic (As) in the grain. Therefore, when rice is grown in areas with contaminated soil or irrigation water, it represents a risk factor for consumers, since As is associated with cancer and other diseases. Different strategies have been used to mitigate micronutrient deficiencies such as Fe and Zn and to prevent As from entering the food chain. Each strategy has its positive and its negative sides. The development of genetically biofortified rice plants with Fe and Zn and with low As accumulation is one of the most promising strategies, since it does not represent an additional cost for farmers, and gives benefits to consumers as well. Considering the importance of genetic improvement (traditional or molecular) to decrease the impact of micronutrient deficiencies such as Fe and Zn and contamination with As, this review aimed to summarize the major efforts, advances, and challenges for genetic biofortification of Fe and Zn and decrease in As content in rice grains.

Recent Findings in Azaphilone Pigments.

Filamentous fungi are known to biosynthesize an extraordinary range of azaphilones pigments with structural diversity and advantages over vegetal-derived colored natural products such agile and simple cultivation in the lab, acceptance of low-cost substrates, speed yield improvement, and ease of downstream processing. Modern genetic engineering allows industrial production, providing pigments with higher thermostability, water-solubility, and promising bioactivities combined with ecological functions. This review, covering the literature from 2020 onwards, focuses on the state-of-the-art of azaphilone dyes, the global market scenario, new compounds isolated in the period with respective biological activities, and biosynthetic pathways. Furthermore, we discussed the innovations of azaphilone cultivation and extraction techniques, as well as in yield improvement and scale-up. Potential applications in the food, cosmetic, pharmaceutical, and textile industries were also explored.

Insights Into Genetic and Molecular Elements for Transgenic Crop Development.

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.

Insights obtained using different modules of the cotton uceA1.7 promoter.

MAIN CONCLUSION: The structure of the cotton uceA1.7 promoter and its modules was analyzed; the potential of their key sequences has been confirmed in different tissues, proving to be a good candidate for the development of new biotechnological tools. 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.

Cloning and molecular characterization of a putative habanero pepper SERK1 cDNA expressed during somatic and zygotic embryogenesis

Background: Plant gene homologs that control cell differentiation can be used as biotechnological tools to study the in vitro cell proliferation competence of tissue culture-recalcitrant species such as peppers. It has been demonstrated that SERK1 homologs enhance embryogenic competence when overexpressed in transformed tissues; therefore, cloning of a pepper SERK1 homolog was performed to further evaluate its biotechnological potential. Results: A Capsicum chinense SERK full-length cDNA (CchSERK1) was cloned and characterized at the molecular level. Its deduced amino acid sequence exhibits high identity with sequences annotated as SERK1 and predicted-SERK2 homologs in the genomes of the Capsicum annuum CM-334 and Zunla-1 varieties, respectively, and with SERK1 homologs from members of the Solanaceae family. Transcription of CchSERK1 in plant tissues, measured by quantitative RT-PCR, was higher in stems, flowers, and roots but lower in leaves and floral primordia. During seed development, CchSERK1 was transcribed in all zygotic stages, with higher expression at 14 days post anthesis. During somatic embryogenesis, CchSERK1 was transcribed at all differentiation stages, with a high increment in the heart stage and lower levels at the torpedo/cotyledonal stages. Conclusion: DNA sequence alignments and gene expression patterns suggest that CchSERK1 is the C. chinense SERK1 homolog. Significant levels of CchSERK1 transcripts were found in tissues with cell differentiation activities such as vascular axes and during the development of zygotic and somatic embryos. These results suggest that CchSERK1 might have regulatory functions in cell differentiation and could be used as a biotechnological tool to study the recalcitrance of peppers to proliferate in vitro.

Plant transcription factors from the homeodomain-leucine zipper family I. Role in development and stress responses.

In front of stressful conditions plants display adaptation mechanisms leading to changes in their morphology, physiology, development and molecular composition. Transcription factors (TFs) play crucial roles in these complex adaptation processes. This work is focused in the homeodomain-leucine zipper I (HD-Zip I) family of TFs, unique to plants. First discovered in 1991, they were identified and isolated from monocotyledonous and dicotyledonous plants showing high structural similarity and diversified functions. These TFs have, besides the homeodomain and leucine zipper, conserved motifs in their carboxy-termini allowing the interaction with the basal machinery and with other regulatory proteins. The model dicotyledonous plant Arabidopsis thaliana has 17 HD-Zip I members; most of them regulated by external stimuli and hormones. These TFs are involved in key developmental processes like root and stem elongation, rosette leaves morphology determination, inflorescence stem branching, flowering and pollen hydration. Moreover, they are key players in responses to environmental stresses and illumination conditions. Several HD-Zip I encoding genes from different species were protected in patents because their overexpression or mutation generates improved agronomical phenotypes. Here we discuss many aspects about these TFs including structural features, biological functions and their utilization as biotechnological tools to improve crops. © 2017 IUBMB Life, 69(5):280-289, 2017.