No abstract

Black pepper (Piper nigrum) is a spice commonly used in kitchens throughout the world. Black pepper production is devastated by a range of pathogenic agents, including Phytophthora capsici and Meloidogyne incognita. Many efforts have been directed towards finding black pepper cultivars that are resistant to these pathogens. In this work, a 39‐accession germplasm panel of species in the Piper family collected throughout Vietnam was described. Preliminary tests using P. capsici inoculation onto leaves were carried out to identify potentially resistant accessions. Next, candidate plants were inoculated with P. capsici mycelial suspension and survival rates were assessed 15, 30 and 45 days postinoculation. In addition, Piper plants were challenged with M. incognita by adding larvae/juveniles to growing pots. Resistance to M. incognita was determined by the number of root galls and the percentage of plants with yellow leaves 1, 2 and 4 months after treatment. Piper accessions were also subjected to a 4‐day waterlogged treatment. Two accessions (HUIB_PH30 and HUIB_PD36) demonstrated high levels of resistance to all biological and water stresses. Micromorphological characterizations revealed that the amount of intercellular spaces in the root cortex correlated with the resistance to P. capsici and waterlogging tolerance. Hence, the abundance of intercellular spaces can serve as a guide for further selection of black pepper accessions that are resistant to common diseases and tolerant to waterlogged conditions.

Black pepper is a well-known export commodity in Vietnam, but pepper production has been decreasing in recent years. The lack of knowledge about the origin and genetic characteristics of pepper varieties may create variety degradation and loss of product quality. Therefore, it is necessary to study the genetic diversity of existing local and imported pepper varieties and effectively propagate and create new varieties with high yields and quality. In this study, RAPD markers were used with 100 RAPD UBC primers to study genetic diversity. Twelve RAPD primers were selected to amplify 39 pepper cultivars, and 40 polymorphic DNA bands were created with sizes ranging from 200 to 1400 bp. Five of the 12 primers amplified all 39 cultivars. The genetic diversity of lines/cultivars in the pepper population is relatively high. The phylogenetic tree of the 39 cultivars has two branches showing similarity ranging from 41.8 to 51%. The first branch includes five pepper individuals, and the second consists of 34 individuals. There is a high diversity among the pepper cultivars in the same population.