Metabolomics allows the identification of biochemical markers that have important roles in plant resistance to pests and diseases by which breeders can select plants based on differences in these compounds. This study examines the range of compounds associated with plant defense against nematodes. Resistant tomato genotypes, GM2 and F1 (GM2 × Hawai 7996), and susceptible genotypes, Gondol Putih and Gondol Hijau, were used in this study. Peroxidase activity was measured colorimetrically using a spectrophotometer. ¹H-NMR (nuclear magnetic resonance) spectroscopy combined with orthogonal projections to latent structures discriminant analysis was used to analyze the metabolites involved in the tomato-nematode interactions. Identified signals were semi-quantitatively calculated by scaling the intensity of the ¹H-NMR to the signals of an internal standard (trimethyl silyl-3-propionic acid) at 0.00 ppm. Resistant plants showed a higher peroxidase activity than susceptible plants. Chemical compounds that differentiated between susceptible and resistant plants were glucose and caffeic acid. Resistant tomatoes were observed to have seven times higher level of glucose than susceptible plants. Glucose is the primary metabolite that acts in the signaling pathways in plant defense mechanisms. Caffeic acid is one of the phenolic compounds alleged to have a negative effect on the nematode.

Three primary species from the Begomovirus genus, Pepper yellow leaf curl Indonesia virus (PepYLCIV), Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV), and Tomato leaf curl New Delhi virus (ToLCNDV), are suspected of spreading throughout pepper production centers, and plants are infected by a single species or a combination of two or three species. This study was conducted to provide complete information about the symptoms, incidence and severity, whitefly biotypes, as well as the dominance status of the three Begomovirus species in pepper-producing areas in Java. A DNA analysis was carried out on leaf samples to identify Begomovirus species and biotypes of B. tabaci collected from 18 areas (16 districts) in lowlands (700 m asl). The DNA analysis showed that B. tabaci biotype B was the most commonly detected in all locations compared to the A, AN, and Q biotypes. The incidence of begomovirus infection was at a high level, 93% and 88.78% in the lowlands and highlands, respectively. However, the severity of begomovirus infection was significantly higher in the lowlands (54.50%) than in the highlands (38.11%). A single infection of PepYLCIV was most dominant in all locations sampled and caused severe infection, followed by a mixed infection with TYLCKaV. Therefore, the current status of begomovirus infection, especially PepYLCIV, can provide advice to farmers using more tolerant and resistant varieties as well as a breeding strategy for resistant pepper varieties.

It is predicted that drought will be more frequent and sustained in the future, which may affect the decline of rubber tree production. Therefore, it is critical to research some of the variables related to the drought-resistance mechanism of the rubber tree. As a result, it can be used to guide the selection of new rubber drought-resistance clones. The goal of this study was to identify drought-resistance mechanisms in rubber clones from the high drought factor index (DFI) group using ecophysiological and biochemical variables. The treatments consist of two factors, namely water deficit and contrasting clones based on the DFI variable. The first factor consisted of three levels, namely normal (fraction of transpirable soil water (FTSW) > 0.75), severe water deficit (0.1 < FTSW < 0.20), and recovery condition (FTSW > 0.75 after rewatering). The second factor consisted of seven clones, namely clones G239, GT1 (low DFI), G127, SP 217, PB 260 (moderate DFI), as well as G206 and RRIM 600 (high DFI). RRIM 600 had the highest DFI among the other clones as a drought-tolerance mechanism characteristic. Furthermore, clones RRIM 600, GT1, and G127 had lower stomatal conductance and transpiration rate than drought-sensitive clone PB 260. As a result, as drought avoidance mechanisms, clones RRIM 600, GT1, and G127 consume less water than clone PB 260. These findings indicated that clone RRIM 600 was a drought-resistant clone with drought tolerance and avoidance mechanisms.

Ralstonia solanacearum is the pathogen responsible for wilting, yield losses, and death in tomato plants. The use of resistant cultivars has been proven as the most appropriate solution to controlling this pathogen. Therefore, further study of host-plant resistance mechanisms in tomatoes is urgently needed. ¹H-NMR (nuclear magnetic resonance) spectroscopy combined with multivariate data analysis has been used to identify the biochemical compounds that play a crucial role in the defense mechanisms of tomato against bacterial wilt. Eleven metabolites consisting of amino acids, sugars and organic acids were identified and presented at different concentrations in each cultivar. Leucine and valine were determined as distinguishable metabolites of resistant and susceptible cultivars. Permata and Hawaii 7996 as resistant cultivars had a significant decrease of valine after inoculation about 1.5–2 times compared to the susceptible cultivar (GM2). Meanwhile, the resistant cultivars had a higher level of leucine, about 1.3–1.5 times compared to the susceptible ones. Synthesis of leucine and valine are linked as a member of the pyruvate family. Therefore, the decrease in valine may be related to the higher need for leucine to form the leucine-rich receptor, which plays a role in the plant’s immune system against the bacterial wilt.

Sari IA, Murti RH, Misnawi, Putra ETS, Susilo AW. 2021. Sensory profiles of cocoa genotypes in Indonesia. Biodiversitas 23: 648-654. The Cocoa flavor is influenced by genetic factors and has an important role in increasing the added value of beans as specialty products. For this reason, superior genotypes with specific and unique flavors should be identified as fine flavor cocoa (FFC) products. This study was conducted to obtain genotypes with sensory quality and specific profiles. Ten clones under three groups were used: Forastero (KW 516 and KEE 2), Trinitario with purple beans (ICCRI 03, ICCRI 07, ICCRI 09, MCC 02, Sulawesi 1, Sulawesi 2, and TSH 858), and Trinitario with white beans (DR 2). Genotypes were assigned using a completely randomized block design with three replications. A sensory test was performed by three trained and certified panelists using the Indonesian Coffee and Cocoa Research Institute (ICCRI) and Guittard Chocolate Company standards. The attributes, acidity, bitterness, astringency, fresh fruit, browned fruit, floral aroma, woody aroma, spicy, nutty taste, and browned/roasted appearance of cocoa were evaluated on a scale of 1-10. Data were examined through ANOVA, flavor character profiling, PCA Biplot, and dendrogram analysis in STAR 2.0.1, Microsoft Excel 2019, and R Studio. Results showed that the genotypes significantly influenced the chemical content of the beans, and each genotype had a specific flavor character. The genotypes were classified into three groups based on flavor characters via PCA biplot and dendrogram analysis. Two groups of aromatic genotypes had the potential to develop FFC products with weak (DR 2) and strong cocoa taste (ICCRI 09, ICCRI 03, ICCRI 07, MCC 02, and TSH 858). Conversely, the nonaromatic cocoa groups with strong taste were KEE 02, KW 516, Sulawesi 1, and Sulawesi 2. Therefore, the intensity of floral and nutty aromas significantly affected the overall quality of cocoa flavor.