Morphological and molecular investigation of the reactions of some colored bean genotypes against the root-knot nematode Meloidogyne javanica

The bean plant (Phaseolus vulgaris) is an important agricultural product both in Turkiye and globally, and during its cultivation, it is exposed to biotic and abiotic stress factors. Among these stress factors, root-knot nematodes (Meloidogyne spp.), which are plant parasitic nematodes, cause damage by inducing galls on the roots of the bean plant. However, the morphological and molecular effects of root-knot nematodes on colored bean genotypes are yet to be fully understood. This study aimed to determine the morphological, molecular, phytochemical, hormonal, and seed protein changes caused by the infection of root-knot nematode Meloidogyne javanica on 21 colored bean genotypes and Barbunya. The result of the study revealed that M. javanica caused morphological changes occurring during the interactions of some colored bean genotypes. The R11 genotype was found to be the most susceptible (with the highest nematode population increase), while the R12 genotype had a lower nematode population compared to the initial population. Furthermore, it was determined that the root-knot nematode M. javanica had negative effects on the development parameters of bean genotypes. Through genome-wide identification, the gene expression of the OPR gene family at 1, 3, 7, and 14 days post-infection showed differences between the susceptible (R11) and tolerant (R12) plants. Phenolic compounds varied between control and nematode-infected plants. Nematode infection also led to changes in phenolic compounds and amino acids among genotypes. Additionally, the protein content in the seeds was found to be higher in the nematode-infected plants. The nematode infection has increased the total protein level from 17.5% to 23.4%. Under nematode stress, phenolic compounds (e.g., chlorogenic acid, resveratrol) have increased, contributing to the development of resistance. Additionally, the increase in amino acids such as L-lysine and L-proline has been found to be effective in combating biotic stress. This study represents an important step toward a more detailed understanding of the relationship between root-knot nematodes and colored bean genotypes in Turkiye and is expected to guide future breeding studies.