Raúl Herrera

The agro-industrial sector generates large volumes of fruit waste each year, leading to environmental concerns and sustainability challenges. In this study, we evaluate the potential of fruit residues—apple, pear, blueberry, tomato, papaya, and a mixed fruit juice blend—as alternative sources of high-value polysaccharides, including pectins, hemicelluloses, and cellulose. Additionally, white strawberry, included as a reference from fresh fruit rather than agro-industrial waste, was analyzed to expand the comparative framework. These biopolymers, naturally derived from the plant cell wall, are renewable and biodegradable, and they possess physicochemical properties suitable for applications in food, pharmaceutical, cosmetic, textile, and bioenergy industries. Using a combination of cell wall fractionation, biochemical characterization, and immunodetection of specific structural domains, we identified significant variability in polysaccharide composition and structure among the samples. Blueberry, pear, and apple residues showed high levels of rhamnogalacturonan-I (RG-I) with extensive branching, while variations in rhamnogalacturonan-II (RG-II) dimerization and the degree of methylesterification of homogalacturonan were also observed. These structural differences are key to determining the gelling properties and functional potential of pectins. In the hemicellulose fractions, xylans and xyloglucans with distinct substitution patterns were especially abundant in apple and pear waste. Our findings demonstrate that fruit processing waste holds significant promise as a sustainable source of structurally diverse polysaccharides. These results support the reintegration of agro-industrial residues into production chains and emphasize the need for environmentally friendly extraction methods to enable industrial recovery and application. Overall, this study contributes to advancing a circular bioeconomy by transforming underutilized plant waste into valuable functional materials.

A novel MADS-box transcription factor from Pinus radiata D. Don was characterized. PrMADS11 encodes a protein of 165 amino acids for a MADS-box transcription factor belonging to group II, related to the MIKC protein structure. PrMADS11 was differentially expressed in the stems of pine trees in response to 45° inclination at early times (1 h). Arabidopsis thaliana was stably transformed with a 35S::PrMADS11 construct in an effort to identify the putative targets of PrMADS11. A massive transcriptome analysis revealed 947 differentially expressed genes: 498 genes were up-regulated, and 449 genes were down-regulated due to the over-expression of PrMADS11. The gene ontology analysis highlighted a cell wall remodeling function among the differentially expressed genes, suggesting the active participation of cell wall modification required during the response to vertical stem loss. In addition, the phenylpropanoid pathway was also indicated as a PrMADS11 target, displaying a marked increment in the expression of the genes driven to the biosynthesis of monolignols. The EMSA assays confirmed that PrMADS11 interacts with CArG-box sequences. This TF modulates the gene expression of several molecular pathways, including other TFs, as well as the genes involved in cell wall remodeling. The increment in the lignin content and the genes involved in cell wall dynamics could be an indication of the key role of PrMADS11 in the response to trunk inclination.

Hormones act as master ripening regulators. In non-climacteric fruit, ABA plays a key role in ripening. Recently, we confirmed in Fragaria chiloensis fruit that in response to ABA treatment the fruit induces ripening-associated changes such as softening and color development. In consequence of these phenotypic changes, transcriptional variations associated with cell wall disassembly and anthocyanins biosynthesis were reported. As ABA stimulates the ripening of F. chiloensis fruit, the molecular network involved in ABA metabolism was analyzed. Therefore, the expression level of genes involved in ABA biosynthesis and ABA perception was quantified during the development of the fruit. Four NCED/CCDs and six PYR/PYLs family members were identified in F. chiloensis. Bioinformatics analyses confirmed the existence of key domains related to functional properties. Through RT-qPCR analyses, the level of transcripts was quantified. FcNCED1 codifies a protein that displays crucial functional domains, and the level of transcripts increases as the fruit develops and ripens, in parallel with the increment in ABA. In addition, FcPYL4 codifies for a functional ABA receptor, and its expression follows an incremental pattern during ripening. The study concludes that FcNCED1 is involved in ABA biosynthesis; meanwhile, FcPYL4 participates in ABA perception during the ripening of F. chiloensis fruit.

Hormones act as master ripening regulators. In non-climacteric fruit ABA plays a key role in ripening. Recently we confirmed in Fragaria chiloensis fruit that in response to ABA treatment the fruit induces ripening associated changes such as softening and color development. In consequence with these phenotypic changes, transcriptional variations associated with cell wall disassembly and anthocyanins biosynthesis were reported. As ABA stimulates ripening of F. chiloensis fruit, the molecular network involved in ABA metabolism was analyzed. Therefore, the expression level of genes involved in ABA biosynthesis and ABA perception were quantified during development of the fruit. Four NCED/CCDs and 6 PYR/PYLs family members were identified in F. chiloensis. Bioinformatics analyses confirmed the existence of key domains related to functional properties. Through RT-qPCR analyses the level of transcripts were quantified. FcNCED1 codifies a protein that displays crucial functional domains and the level of transcripts increased as the fruit develops and ripens, in parallel with the increment in ABA. In addition, FcPYL4 codifies for a functional ABA receptor and its expression follows an incremental pattern during ripening. The study concludes that FcNCED1 is involved in ABA biosynthesis, meanwhile FcPYL4 participates in ABA perception during ripening of F. chiloensis fruit.

Ozone depletion at southern latitudes has recently increased the fluence of ultraviolet-B (UV-B) radiation striking the ground. This phenomenon has sparked much interest in unravelling the effects of this harmful radiation on living systems. UV-B radiation triggers several responses that affect plant physiology, morphology and biochemistry. In this study, the effect of supplemental UV-B radiation on DNA profile and chlorophyll a (CHl a) fluorescence characteristics were analyzed. An increase in the genetic variability of irradiated plants was observed in the Inter Sequence Simple Repeats products. The effect on photosynthesis was studied through fluorescence emissions. The obtained data showed that photochemical quenching (qP) decreased in irradiated plants. This effect may be attributed to a decrease in the number of open reaction centers of photosystem II (PSII) as suggested by the decreased values of minimal and maximal fluorescence. Likewise, non-photochemical quenching (NPQ) increased in both control and irradiated groups, but treated plants presented lower NPQ values than controls. The heat dissipation mechanism was also altered, probably due to a decrease in the yield of Fm´. According to these findings, UV-B radiation affects the CHl a fluorescence mechanisms and modifies DNA profile. Consequently, these changes influence the yield and growth of plants, which is an important consideration given the current climate change situation.

Fragaria chiloensis (Chilean strawberry) is a native species that produces fruit with an exotic pinkish color and a fruity aroma. It has a non-climacteric pattern of fruit ripening, and it is the mother of the commercial Fragaria x ananassa. The ripening of F. chiloensis fruit seems stimulated by ABA, and a complete set of genes participate in its softening, color, and aroma development. In addition, a set of transcription factors regulate the entire process, but few of them have been described. Over the last two decades, RNA-seq was used to identify genes at three fruit development/ripening stages, named C2 (unripe, large green) to C4 (full ripe), in whole fruit and fruit without achenes. A total of 204,754 contigs were assembled considering all samples, obtaining an N50 of 1.125 bp. Differentially expressed genes (DEGs) between two samples were identified, obtaining a total of 77,181 DEGs. Transcripts for genes involved in ABA biosynthesis present high and differential expression during the C2, C3, and C4 stages. Besides, contigs corresponding to ABA receptors, which interact with a regulatory network, are also differentially expressed. Genes associated with cell wall remodeling and those involved in flavonoid synthesis were also differentially expressed. An interaction network was built considering differentially expressed genes for the phenylpropanoid and flavonoid molecular pathways and having FcMYB1 as a transcription factor regulator. Identifying key genes could give an option to control the ripening of this non-climacteric fruit.