Resistant pepper carrying N, Me1, and Me3 have different effects on penetration and reproduction of four major meloidogyne species

Authors: HAJIHASSANI, ABOLFAZL - University Of Georgia; Rutter, William; LUO, XUELIN - University Of Georgia

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2018
Publication Date: 1/1/2019
Citation: Hajihassani, A., Rutter, W.B., Luo, X. 2019. Resistant pepper carrying N, Me1, and Me3 have different effects on penetration and reproduction of four major meloidogyne species. Journal of Nematology. 51:1-9. https://doi.org/359780.

Interpretive Summary: Root-knot nematodes (genus Meloidogyne) are a serious pest of pepper around the world. Although there are pepper genes that provide resistance against these pests, each plant gene provides resistance to only a limited number of root-knot nematode species and/or isolates and they function in different ways. Understanding the mechanism by which specific plant resistance genes function to defend against specific pathogen isolates can help pathologists and breeders design and deploy cultivators in the field that have more durable resistance. In this study we tested pepper lines with different and well-defined sets of root-knot nematode resistance genes by infecting them with isolates from 4 different root-knot nematode species collected from the southeastern US. Each pepper line was assessed for its resistance to nematode penetration, nematode induced galling, and nematode reproduction. The results provide new data on penetration rates of nematodes into plants with different resistance genes, and provide data indicating that all of these pepper resistance genes are effective against Meloidogyne haplanaria, a species that is known to overcome other resistance genes in tomato. These data contribute to the body of knowledge of how root-knot nematode resistance in peppers functions, and could help researchers and breeders develop new root-knot nematode resistant pepper lines.

Technical Abstract: Root-knot nematode (Meloidogyne spp.) exhibits a substantial problem in pepper production, causing reduction in yield throughout the world. Continued assessment for root-knot resistance is important for developing new resistance cultivars. In this study, the effect of Me and N genes on the penetration and reproduction of M. incognita race 3, M. arenaria race 1, M. javanica, and M. haplanaria was examined under controlled greenhouse conditions using susceptible and resistance cultivars, and four isogenic pepper lines (HDA-149, HDA-330, PM-217, and PM-687) differing in presence or absence of resistant genes. The penetration and resistance responses of pepper cultivars/lines differed depending on the nematode species. More second-stage juveniles penetrated roots of susceptible control cultivar Mellow Star than roots of resistant cultivars/lines. Although, there was no significant difference in the nematode penetration among lines carrying resistance genes 1 and 3 days after inoculation (DAI), variability in the penetration of M. incognita, M. javanica and M. haplanaria was observed 5 DAI. This demonstrates the variability among pepper cultivar/lines to invasion by Meloidogyne spp. Based on nematode gall index (GI) and reproduction factor (RF), Charleston Belle, HDA-149, PM-217 and PM-687 showed very high resistance (GI < 1 and RF < 0.1) to M. incognita, M. arenaria, and M. javanica. HDA-330 was also highly resistant to M. arenaria and M. javanica, but it was found resistant to M. incognita, with an RF value of 0.90. Although, all the Meloidogyne-resistant pepper lines evaluated were resistant to M. haplanaria, the susceptible cultivar Mellow Star was a good host for the nematode having an RF value of 8.1. The N, Me1, Me2, Me3, Me4, and Me7 genes controlled resistance to reproduction of all species of Meloidogyne examined.