Resistant Pepper Carrying N, Me1, and Me3 have Different Effects on Penetration and Reproduction of Four Major Meloidogyne species

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 resistant pepper lines/cultivars (Mellow Star, Yolo Wonder B, Charleston Belle, HDA-149, HDA-330, PM-217, and PM-687) differing in the presence or absence of resistant genes. The penetration and resistance responses of these pepper 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 resistant lines 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 different nematode resistance genes 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. Although, all the Meloidogyne-resistant pepper lines evaluated were resistant to M. javanica and M. haplanaria, the susceptible cultivar Mellow Star was a good host for all nematode species having an RF ranging from 8.1 to 34.7. The N, Me1, and Me3 genes controlled resistance to reproduction of all species of Meloidogyne examined.

Differences in parasitism of root-knot nematodes (Meloidogyne spp.) on oilseed radish and oat

“…Least-squares means (LS-means) t-tests demonstrating if the mean was significantly different from 0 were used to determine whether the nematode Rf was different from 1 (the base 10 algorithm of 1 is 0). Therefore, single t-tests that showed the treatment mean was significantly different from 0 indicated that the Rf deviated significantly from 1 (Hajihassani et al, 2020).…”

“…Management of plant-parasitic nematodes in vegetable plasticulture or bare-ground systems in the southern US relies heavily on pre-plant fumigation of soil with 1,3-dichloropropene (Telone II), Chloropicrin or metam sodium (Vapam), followed by in-season application of non-fumigant nematicides (Hajihassani, Davis, and Timper, 2019). One of the alternative management methods is the use of nematodesuppressive cover/trap crops to reduce nematode populations in soil.…”

“…The absence of nematodes and giant cells in the resistant cultivars may be attributed to inhibition of juvenile development in the root tissues. In contrast, the root tissues of susceptible oilseed and oat cultivars had several hypertrophied and multinucleated cells due to root-knot nematode development (Cabasan et al, 2014;Hajihassani et al, 2020). Giant cells serve as an important source of nutrients for nematode growth and reproduction.…”

“…Cross sections 4 to 5 µm thick were prepared using a rotary microtome (RM2125 RTS, Leica Biosystems, Nussloch, Germany), and then mounted on glass slides. The sections were stained with Hematoxylin-Eosin (HE), evaluated microscopically at 40 to 100 × magnifications (Olympus BX43, Olympus, Tokyo, Japan) and images captured using a digital camera (Olympus DP73, Olympus, Tokyo, Japan) (Hajihassani et al, 2020).…”

“…Meloidogyne spp. are serious pathogens of multiple vegetable crops in the southern United States and worldwide ( Johnson et al, 1992 ; Jones et al, 2013 ; Hajihassani, Davis, and Timper, 2019 ; Hajihassani, Rutter, and Luo, 2019 ). In Georgia, more than 66% of vegetable growing areas are infested with at least one species of root-knot nematodes at the level of one nematode per 100 cm 3 of soil where management is needed to achieve economically reasonable yields ( Marquez and Hajihassani, 2019 ).…”