Genome-Wide Identification of the Aconitase Gene Family in Tomato (Solanum lycopersicum) and CRISPR-Based Functional Characterization of SlACO2 on Male-Sterility.

Tomato (Solanum lycopersicum) is one of the most cultivated vegetables in the world due to its consumption in a large variety of raw, cooked, or processed foods. Tomato breeding and productivity highly depend on the use of hybrid seeds and their higher yield, environmental adaption, and disease tolerance. However, the emasculation procedure during hybridization raises tomato seed production costs and labor expenses. Using male sterility is an effective way to reduce the cost of hybrid seeds and ensure cultivar purity. Recent developments in CRISPR genome editing technology enabled tomato breeders to investigate the male sterility genes and to develop male-sterile tomato lines. In the current study, the tomato Acotinase (SlACO) gene family was investigated via in silico tools and functionally characterized with CRISPR/Cas9-mediated gene disruption. Genome-wide blast and HMM search represented two SlACO genes located on different tomato chromosomes. Both genes were estimated to have a segmental duplication in the tomato genome due to their identical motif and domain structure. One of these genes, SlACO2, showed a high expression profile in all generative cells of tomato. Therefore, the SlACO2 gene was targeted with two different gRNA/Cas9 constructs to identify their functional role in tomatoes. The gene was mutated in a total of six genome-edited tomato lines, two of which were homozygous. Surprisingly, pollen viability was found to be extremely low in mutant plants compared to their wild-type (WT) counterparts. Likewise, the number of seeds per fruit also sharply decreased more than fivefold in mutant lines (10-12 seeds) compared to that in WT (67 seeds). The pollen shape, anther structures, and flower colors/shapes were not significantly varied between the mutant and WT tomatoes. The mutated lines were also subjected to salt and mannitol-mediated drought stress to test the effect of SlACO2 on abiotic stress tolerance. The results of the study indicated that mutant tomatoes have higher tolerance with significantly lower MDA content under stress conditions. This is the first CRISPR-mediated characterization of ACO genes on pollen viability, seed formation, and abiotic stress tolerance in tomatoes.

Chemical and structural quality traits during postharvest ripening regulated by chromosome segments from a wild relative of tomato Solanum pennellii IL4-2 and IL5-1.

Tomato is usually harvested at an early ripening stage with high firmness suitable for storage and transportation but lacks many quality parameters such as sugars, organic acids, and phenolics. In a recent study, we have selected introgression lines (ILs) IL4-2 and IL5-1, developed from a cross between the Solanum pennellii and the Solanum lycopersicum M82, that exhibit differentiated postharvest shelf-life characteristics in the fruit compared to M82 and the rest of the ILs. Here, we first structurally and biochemically characterized IL4-2, IL5-1, and their parent M82 to decipher the cell wall mechanistic difference between soft (IL4-2) and firm (IL5-1) lines at two postharvest ripening periods. Generally, IL4-2 had more active cell wall modifications in terms of ripening-related gene expression, water-soluble pectin, and cell wall structure under the microscope, which probably makes this line softer than IL5-1. We also evaluated these lines based on commercial quality parameters, sugars, phenolics, organic, and amino acids to gain insight into their commercial and functional quality and reveal noticeable differences. In summary, the contribution of the S. pennellii IL5-1 and IL4-2 to the shelf life of the tomato was structurally characterized, and the component differences meeting the quality criteria were revealed.

Pectate lyases: Their role in plants and importance in fruit ripening.

Plant cell walls are complex structures that are modified throughout development. They are a major contributor to the properties of plant structure and act as barriers against pathogens. The primary cell walls of plants are composed of polysaccharides and proteins. The polysaccharide fraction is divided into components cellulose, hemicelluloses and pectin, are all modified during fruit ripening. Pectin plays an important role in intercellular adhesion and controlling the porosity of the wall. A large number of pectin degrading enzymes have been characterised from plants and they are involved in numerous aspects of plant development. The role of pectate lyases in plant development has received little attention, probably because they are normally associated with the action of plant pathogenic organisms. However their importance in plant development and ripening is now becoming well established and new information about the role of pectate lyases in plant development forms the focus of this review.

Health benefits and bioactive compounds of eggplant.

Eggplant is a vegetable crop that is grown around the world and can provide significant nutritive benefits thanks to its abundance of vitamins, phenolics and antioxidants. In addition, eggplant has potential pharmaceutical uses that are just now becoming recognized. As compared to other crops in the Solanaceae, few studies have investigated eggplant's metabolic profile. Metabolomics and metabolic profiling are important platforms for assessing the chemical composition of plants and breeders are increasingly concerned about the nutritional and health benefits of crops. In this review, the historical background and classification of eggplant are shortly explained; then the beneficial phytochemicals, antioxidant activity and health effects of eggplant are discussed in detail.

Fruit Softening: Revisiting the Role of Pectin.

Fruit softening, which is a major determinant of shelf life and commercial value, is the consequence of multiple cellular processes, including extensive remodeling of cell wall structure. Recently, it has been shown that pectate lyase (PL), an enzyme that degrades de-esterified pectin in the primary wall, is a major contributing factor to tomato fruit softening. Studies of pectin structure, distribution, and dynamics have indicated that pectins are more tightly integrated with cellulose microfibrils than previously thought and have novel structural features, including branches of the main polymer backbone. Moreover, recent studies of the significance of pectinases, such as PL and polygalacturonase, are consistent with a causal relationship between pectin degradation and a major effect on fruit softening.

Genetic improvement of tomato by targeted control of fruit softening.

Controlling the rate of softening to extend shelf life was a key target for researchers engineering genetically modified (GM) tomatoes in the 1990s, but only modest improvements were achieved. Hybrids grown nowadays contain 'non-ripening mutations' that slow ripening and improve shelf life, but adversely affect flavor and color. We report substantial, targeted control of tomato softening, without affecting other aspects of ripening, by silencing a gene encoding a pectate lyase.