New York 14853 (R.P.M., J.J.G.)Color changes often accompany the onset of ripening, leading to brightly colored fruits that serve as attractants to seeddispersing organisms. In many fruits, including tomato (Solanum lycopersicum) and pepper (Capsicum annuum), there is a sharp decrease in chlorophyll content and a concomitant increase in the synthesis of carotenoids as a result of the conversion of chloroplasts into chromoplasts. The green-flesh (gf) and chlorophyll retainer (cl) mutations of tomato and pepper, respectively, are inhibited in their ability to degrade chlorophyll during ripening, leading to the production of ripe fruits characterized by both chlorophyll and carotenoid accumulation and are thus brown in color. Using a positional cloning approach, we have identified a point mutation at the gf locus that causes an amino acid substitution in an invariant residue of a tomato homolog of the STAY-GREEN (SGR) protein of rice (Oryza sativa). Similarly, the cl mutation also carries an amino acid substitution at an invariant residue in a pepper homolog of SGR. Both GF and CL expression are highly induced at the onset of fruit ripening, coincident with the ripening-associated decline in chlorophyll. Phylogenetic analysis indicates that there are two distinct groups of SGR proteins in plants. The SGR subfamily is required for chlorophyll degradation and operates through an unknown mechanism. A second subfamily, which we have termed SGR-like, has an as-yet undefined function.

BackgroundRosea1 (Ros1) and Delila (Del) co-expression controls anthocyanin accumulation in snapdragon flowers, while their overexpression in tomato strongly induces anthocyanin accumulation. However, little data exist on how Del expression alone influences anthocyanin accumulation.ResultsIn tobacco (Nicotiana tabacum ‘Xanthi’), Del expression enhanced leaf and flower anthocyanin production through regulating NtCHS, NtCHI, NtF3H, NtDFR, and NtANS transcript levels. Transgenic lines displayed different anthocyanin colors (e.g., pale red: T0-P, red: T0-R, and strong red: T0-S), resulting from varying levels of biosynthetic gene transcripts. Under salt stress, the T2 generation had higher total polyphenol content, radical (DPPH, ABTS) scavenging activities, antioxidant-related gene expression, as well as overall greater salt and drought tolerance than wild type (WT).ConclusionWe propose that Del overexpression elevates transcript levels of anthocyanin biosynthetic and antioxidant-related genes, leading to enhanced anthocyanin production and antioxidant activity. The resultant increase of anthocyanin and antioxidant activity improves abiotic stress tolerance.

Factors affecting shoot regeneration were optimized in order to develop an efficient protocol for shoot regeneration in leaf explants of the chrysanthemum (Chrysanthemum morifolium Ramat) cultivar Shinma. The maximum number of shoots per explant (9.7) was regenerated in leaf explants of 6-week-old donor plants cultured on Murashige-Skoog medium containing a combination of 0.5 mg L -1 6-benzyladenine and 0.5 mg L -1 a-naphthaleneacetic acid with initial dark treatment for 7 days. Among the different auxins tested, indolebutyric acid was the most effective for root induction and development, whereas the presence of ethylene inhibitors strongly suppressed shoot regeneration. Ploidy levels were analyzed by flow cytometry: there was no ploidy variation between the regenerated plants and the mother plant grown under greenhouse conditions. The new protocol will facilitate genetic transformation and micropropagation of chrysanthemum cv. Shinma.

Background As strawberries are susceptible to somaclonal variation when propagated by tissue culture techniques, it is challenging to obtain the true-to-type plants necessary for continuous production of fruits of stable quality. Therefore, we aimed to develop an in vitro propagation method for the production of true-to-type plants of five different strawberry cultivars from meristems cultured in media containing different concentrations of kinetin (Kn). Results For all the cultivars, shoot induction was successful only in the meristems cultured in the medium without Kn and the medium containing 0.5 mg L −1 Kn. The shoots obtained from explants cultured in media supplemented with 0.5 mg L −1 Kn exhibited better plant growth parameters than those cultured in media without Kn and were genetically stable when compared with conventionally propagated plants for all the cultivars. Vegetative and sexual characters and fruit quality attributes observed in the plants derived from meristems cultured on 0.5 mg L −1 Kn and the conventionally propagated plants were not significantly different when grown for three continuous growing seasons under greenhouse conditions. Conclusion The culture of meristems in the medium containing 0.5 mg L −1 Kn is suitable for the efficient propagation of true-to-type plants of different strawberry cultivars and continuous production of fruits with stable quality. Hence, we expect that the method presented in this study will be helpful for the commercial production of true-to-type plants generated in vitro for other strawberry cultivars. Electronic supplementary material The online version of this article (10.1186/s13007-019-0421-0) contains supplementary material, which is available to authorized users.

BackgroundLIM (Lin-11, Isl-1 and Mec-3 domains) genes have been reported to trigger the formation of actin bundles, a major higher-order cytoskeletal assembly, in higher plants; however, the stress resistance related functions of these genes are still not well known. In this study, we collected 22 LIM genes designated as Brassica rapa LIM (BrLIM) from the Brassica database, analyzed the sequences, compared them with LIM genes of other plants and analyzed their expression after applying biotic and abiotic stresses in Chinese cabbage.ResultsUpon sequence analysis these genes were confirmed as LIM genes and found to have a high degree of homology with LIM genes of other species. These genes showed distinct clusters when compared to other recognized LIM proteins upon phylogenetic analysis. Additionally, organ specific expression of these genes was observed in Chinese cabbage plants, with BrPLIM2a, b, c, BrDAR1, BrPLIM2e, f and g only being expressed in flower buds. Furthermore, the expression of these genes (except for BrDAR1 and BrPLIM2e) was high in the early flowering stages. The remaining genes were expressed in almost all organs tested. All BrDAR genes showed higher expression in flower buds compared to other organs. These organ specific expressions were clearly correlated with the phylogenetic grouping. In addition, BrWLIM2c and BrDAR4 responded to Fusarium oxysporum f. sp. conglutinans infection, while commonly two BrDARs and eight BrLIMs responded to cold, ABA and pH (pH5, pH7 and pH9) stress treatments in Chinese cabbage plants.ConclusionTaken together, the results of this study indicate that BrLIM and BrDAR genes may be involved in resistance against biotic and abiotic stresses in Brassica.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-641) contains supplementary material, which is available to authorized users.