Color and pungency are the two main factors of chili peppers that determine their quality and final market price. In this study, we investigated the effect of light-emitting diodes (LEDs) on fruit color and primary and secondary metabolites (capsaicinoids) in Capsicum annuum L. cv. Cheonyang. High-performance liquid chromatography analysis of acetonitrile extract of chili fruits revealed enhanced capsaicinoid contents in blue LEDs (180 ± 6.32 mg/100 g) when compared with fluorescent light (54 ± 3.12 mg/100 g). However, color of chili pepper was remarkably changed under different light treatments. Among these, high ASTA color values and chromatic parameters (L*, a*, b*, C*, and H°) were recorded under red plus blue LED, further indicating red plus blue LED is responsible for most vivid color development compared with monochromatic red or blue LEDs. In addition, we found total carbohydrate [22.32 mg·g−1 fresh weight (FW)], reducing sugars (8.27 mg·g−1 FW), starch (14.05 mg·g–1 FW), carotenoids (6.15 mg·g−1 FW), and protein (4.83 mg·g−1 FW) were significantly high under red plus blue LED. These results showed that there were significant differences of plant growth and production of various metabolites among the different LEDs. Furthermore, blue LED showed a relatively higher rate of capsaicinoid production and red plus blue LED produced striking color development in chili peppers. Therefore, the results presented here might serve as an alternative strategy for nutritional improvement (color, oleoresin, and pungency) of chili peppers.

Abiotic stresses such as heat, drought, and salinity are major environmental constraints that limit potato (Solanum tuberosum L.) production worldwide. Previously, we found a potential thermo-tolerance gene, named StnsLTP1 from potato using yeast functional screening. Here, we report the functional characterization of StnsLTP1 and its role in multiple abiotic stresses in potato plants. Computational analysis of StnsLTP1 with other plant LTPs showed eight conserved cysteine residues, and four α-helices stabilized by four disulfide bridges. Expression analysis of StnsLTP1 gene showed differential expression under heat, water-deficit and salt stresses. Transgenic potato lines over-expressing StnsLTP1 gene displayed enhanced cell membrane integrity under stress conditions, as indicated by reduced membrane lipid per-oxidation, and hydrogen peroxide content relative to untransformed (UT) control plants. In addition, transgenic lines over-expressing StLTP1 also exhibited increased antioxidant enzyme activity with enhanced accumulation of ascorbates, and up-regulation of stress-related genes including StAPX, StCAT, StSOD, StHsfA3, StHSP70, and StsHSP20 compared with the UT plants. These results suggests that StnsLTP1 transgenic plants acquired improved tolerance to multiple abiotic stresses through enhanced activation of antioxidative defense mechanisms via cyclic scavenging of reactive oxygen species and regulated expression of stress-related genes.

The present study aims to investigate the numerous factors influencing Agrobacterium tumefaciens-mediated genetic transformation of Chinese cabbage (Brassica rapa ssp. pekinensis). Factors affecting transformation efficiency, such as age of explants, Agrobacterium concentration, and effect of acetosyringone, pre-cultivation, infection and co-cultivation time of Agrobacterium were examined. The pre-cultured hypocotyls from young seedlings prior to exposure to Agrobacterium showed higher shoot regeneration. The plant transformation with the modest A. tumefaciens concentrations (0.8 OD) and the 3 days co-cultivation periods increased transformation efficiency. Plant growth hormones [1-naphthyl acetic acid (NAA) and 6-benzyl amino purine (BAP)] were essential for callus and shoot formation. Root formation was effective in half strength MS medium without supplementation of root-inducing hormones. To maintain selection pressure, plant subculture was carried out every 2 weeks with selective antibiotics. The putative transgenic plants were acclimatized in the greenhouse. Polymerase chain reaction was performed to confirm the integration of T-DNA into the genome of transgenic plants. A transformation efficiency of 15 % was obtained. This protocol allows effective transformation and indirect regeneration of Brassica rapa.

Potato (S. tuberosum) is a highly heat-sensitive crop; a slight rise from optimal temperature can lead to drastic decline in tuber yield. Despite several advancements made in breeding for thermo-tolerant potato, molecular mechanisms governing thermo-tolerance is poorly understood. The first step towards understanding the thermo-tolerance mechanism is to identify the key genes involved in it. Here we used a yeast-based functional screening method to identify, characterize and classify potato genes with potentials to impart heat tolerance. We constructed two cDNA expression libraries from heat-stressed potato plants (35 °C) after 2 and 48 h of treatment. 95 potential candidate genes were identified based on enhanced ability of yeast cells over-expressing heterologous potato cDNA sequences to tolerate heat stress. Cross-resistance analysis of these heat-tolerant yeast clones to other abiotic stresses indicated that 20 genes were responsive to drought, 14 to salt and 11 to heat/drought/salt stresses. Comparison of 95 genes with reported whole potato transcriptome data showed that majority of them have varying expression patterns under heat, drought and salt stresses. The expression pattern was validated by analyzing the expression of 22 randomly selected genes under various stresses using qPCR. Gene ontology (GO) enrichment analysis of these 95 genes indicated that most of them are involved in various cellular metabolism, signal transduction, response to stress and protein folding, suggesting possible role of these genes in heat tolerance of potato. Genes identified from this study can be potential candidates for engineering heat tolerance as well as broad-spectrum abiotic stress tolerance of potato.

Simple sequence repeats (SSRs) derived from expressed sequence tags (ESTs) are important resources for gene discovery and mapping. In this study, we developed EST-based SSR (eSSRs) markers and assessed their ability in mapping and transferability. A total of 10 800 unigenes were detected from 18 522 pea EST sequences (December 2009). Screening of 10 800 unigenes by MISA (MIcroSAtellite) revealed 2612 (14.1%) eSSRs in 2395 (12.9%) SSR-containing ESTs from which 577 (24.1%) primer pairs were designed. The most abundant repeat motif identified in eSSR was mononucleotide (85.2%), followed by trinucleotide (10.6%) and dinucleotide (2.8%). Among 108 randomly selected primer pairs, 40 were assessed for mapping and 68 to test cross-species transferability in six leguminous species. Out of 40 primer pairs, 85% produced amplicons, 60% showed polymorphism and 47.5% were mapped. Furthermore, 68 primer pairs revealed high rate of transferability (48-85%) in leguminous species. High levels of polymorphism, reproducibility, presence of alleles (3.8/locus) and transferability revealed the potential use of these eSSR markers in molecular mapping, quantitative trait loci (QTL) analysis and comparative mapping in pea and other legumes.