Integrative Analysis of the Metabolome and Transcriptome of a Cultivated Pepper and Its Wild Progenitor Chiltepin (Capsicum annuum L. var. glabriusculum) Revealed the Loss of Pungency During Capsicum Domestication

Pungency is a unique characteristic of chili peppers (Capsicum spp.) caused by capsaicinoids. The evolutionary emergence of pungency is thought to be a derived trait within the genus Capsicum. However, it is not well-known how pungency has varied during Capsicum domestication and specialization. In this study, we applied a comparative metabolomics along with transcriptomics analysis to assess various changes between two peppers (a mildly pungent cultivated pepper BB3 and its hot progenitor chiltepin) at four stages of fruit development, focusing on pungency variation. A total of 558 metabolites were detected in two peppers. In comparison with chiltepin, capsaicinoid accumulation in BB3 was almost negligible at the early stage. Next, 412 DEGs associated with the capsaicinoid accumulation pathway were identified through coexpression analysis, of which 18 genes (14 TFs, 3 CBGs, and 1 UGT) were deemed key regulators due to their high coefficients. Based on these data, we speculated that downregulation of these hub genes during the early fruit developmental stage leads to a loss in pungency during Capsicum domestication (from chiltepin to BB3). Of note, a putative UDP-glycosyltransferase, GT86A1, is thought to affect the stabilization of capsaicinoids. Our results lay the foundation for further research on the genetic diversity of pungency traits during Capsicum domestication and specialization.

Seed treatment using rhizobacteria as plant growth promotion of two chili variety (Capsicum annuum L.)

The research aims to find out the effect of pre-germination treatment seeds using rhizobacteria as plant growth promotion of two varieties of red chili peppers in the field. The experiment used a randomized design of factorial groups. Factors studied were varieties (V) and rhizobacteria types (R). The variety factor consists of 2 varieties namely PM999 (V1) and Kiyo F1 (V2). While the type of rhizobacteria factor tried consists of 8 treatment, namely, control (R0), Azotobacter sp. (R1), B. megaterium (R2), P. atmuta (R3), B. alvei (R4), Flavobacterium sp. (R5), B. coagulans (R6), B. firmus (R7) and B. pilymixa (Rs). Each treatment was repeated 3 times, so there were 48 experimental units. Each unit of experiment is represented by 5 sample plants. The data was analyzed using ANOVA and continued with DMRT test at real level α = 0.05. The results showed that vegetative growth and production of chili plants until the age of 45 days after planting in each variety is not dependent on the pre-germination treatment of seeds with rhizobacteria. But the varieties of chili plants used affect vegetative growth and production. PM999 varieties are superior to the Kiyo F1 variety. Pre-germination treatment of seeds using rhizobacteria is relatively effective in improving vegetative growth and yield of chili plants. Among the 8 isolates rizobacteria isolate Azotobacter sp., B. megaterium, B. coagulants, Flavobacterium sp., and P. atmuta relatively effective to provide an increased effect on the growth and production of chili plants.

Chili pepper genotypes assay approach for resistance to Aphis gossypii (Hemiptera: Aphididae)

The cotton aphid (Aphis gossypii), is one of the most devastating insect pests for chili pepper that damages the crop and transmits several viruses. Thus far, there is no commercial chili cultivar with effective resistance to cotton aphids (CA). The present study aimed to develop a reliable and practical screening protocol in chili peppers for aphids resistance in the tropical areas. Three no-choice test methods i.e., seedling cage, detached leaf, and clip cage tests have been developed. The experiment was conducted in a randomized complete block design (RCBD) with four replications in a greenhouse at the Gunung Putri, Bogor, West Java, Indonesia. Seven chili pepper genotypes belong to the species Capsicum annuum L. provided by the Department of Agronomy and Horticulture, IPB University, Bogor, Indonesia were used in this study. Chili pepper resistance to aphids was observed through the number of aphids progeny, and aphids fecundity among the genotypes. Two chili genotypes consistently showed low infestation while other genotypes showed the highest infestation with three screening methods. All the methods have a high heritability value (90%–91%), indicating that the evaluated chili genotypes could be used to determine effective screening methods. The correlation between the detached leaf and clip cage tests was significant (r = 0.84, P ≤ 0.05). Therefore, the clip cage test could be used as a reliable and practical screening test for the assay of chili peppers resistance to CA infestation. These information will be helpful in the development of aphid resistant cultivars in the future.

Importance of the Natural Incidence of the Fusarium Genus in Food Crops Established in Northern México

The incidence of the Fusarium genus causing root rot is reviewed in crops showing high importance for food supply and to obtain regular income by farmers in the highlands of Northern México. Pathogen incidence was evaluated under field conditions in multiple sampling locations for common beans (Phaseolus vulgaris L.) and several chili peppers (Capsicum annuum) local cultivars (landraces and bred cultivars). Five commercial plots for registered and certified seed were also evaluated in common beans to be used in the ‘seed refreshing program’ implemented for the cultivar Pinto Saltillo, considered as the main variety sown in the highlands of México. High Fusarium genus incidence and its interactions with other fungi species, such as Rhizoctonia solani and Pythium spp., cause high losses in plant population, commercial yield and seed quality in food crops grown in Northern México. The natural incidence of plant disease caused by the Fusarium genus and its negative effect on crop survival and the reduction of commercial yield and seed quality is fully reviewed. Plant disease resistance, crop breeding and the influence of the environmental conditions were also considered.

The science of “smell” and the noble for “hugs:” making “sense?”

David Julius and Ardem Patapoutian were jointly awarded the 2021 Nobel Prize in Physiology and Medicine for their discoveries of receptors for temperature and touch. It was a phenomenal moment for the scientific community, more for the discovery that forms the basic fabric of our everyday life—ever imagined how life would have been without feeling the aroma around? Or even the dangers of accidentally touching a heated object. Dr Julius and Dr Patapoutian, independently discovered key mechanisms of how living organisms sense heat, cold, and touch. The journey started when Dr Julius, at the University of California, San Francisco, used a key ingredient in hot chili peppers to identify a protein in nerve cells that respond to these stimuli. Using capsaicin, the pungent component of chili peppers, he provided fundamental insights into mechanisms of pain. Then using a meticulous cDNA library-based functional screening from sensory neurons to search for the gene(s) that could confer capsaicin sensitivity, Dr Julius identified for the first time a novel ion channel (now called transient receptor potential [TRP] vanilloid 1) belonging to the family of TRP ion channels associated with the pain sensitivity. A painful exercise indeed! While Prof Julius was exploring the oceans and skies to hunt for sensory pain pathways, quite independently, Dr Patapoutian of Scripps Research Institute La Jolla, California, was searching for a similar thing that seemed to bother him equally. How do we sense touches? After all, there are so many emotions packaged in this small five-letter word, touch. The mother’s touch is the first sensation that every single of us always cherishes. Dr Patapoutian research is centered around finding candidate genes in a mechanosensitive cell line that could respond to mechanical stimuli. After a thorough search, the team identified two mechanically-activated ion channels, PIEZO1 and PIEZO2, representing an entirely novel class of mechanical sensors-based ion channels. What is fascinating is the idea that discovery of the smell and touch receptor stretches far beyond just touch and temperature sensations only. Mutations in other TRP channels are involved in neurodegenerative disorders and skeletal dysplasia, while mutations in PIEZO channels help control critical functions such as respiration and blood pressure regulation. So now, the mysterious world surrounding us looks more transparent and clearer. The molecular landscape is defined with precision. We now have a chemical entity behind all these emotions and intuition. The warm hug that makes our day is now millions of ions crisscrossing the ion channels. There is a different side to this too. How will the world look if everything is defined as a chemical entity? Won’t we lose the charm? After all, so much within the subtleness remains charmful when wrapped within the veil of ignorance. Knowing too much about something steals the show.

Transcriptional Regulation of Ripening in Chili Pepper Fruits (Capsicum spp.)

Chili peppers represent a very important horticultural crop that is cultivated and commercialized worldwide. The ripening process makes the fruit palatable, desirable, and attractive, thus increasing its quality and nutritional value. This process includes visual changes, such as fruit coloration, flavor, aroma, and texture. Fruit ripening involves a sequence of physiological, biochemical, and molecular changes that must be finely regulated at the transcriptional level. In this review, we integrate current knowledge about the transcription factors involved in the regulation of different stages of the chili pepper ripening process.