واکنش سیستم دفاع هورمونی دو پایه مهم پسته ایران به آلودگی نماتد ریشه گرهی Meloidogyne javanic

Pistachio (Pistacia vera L) is one of the most important horticultural products in the world, and it has
high economic and nutritional values. In the last decade, there have been many reports on the damage
of root-knot nematodes, especially Meloidogyne javanica, to mature pistachio trees resulting in a
significant reduction in its production. Using tolerant rootstocks to root-knot nematodes is a
promising approach to confronting root-knot nematode damage in the pistachio orchards. In the
current study, to investigate the phytohormonal defense reactions (jasmonic acid and salicylic acid
hormones) of pistachio seedlings infected with M. javanica, the seeds of two widely used pistachio
rootstocks in Iran, namely “Badami-riz” (susceptible to the nematode) and “Qazvini” (tolerant to the
nematode) was grown in plastic pots containing five kg of a soil mixture consisting of silty soil,
cocopeat and perlite (in a ratio of 5:3:2). The inoculation was carried out with a suspension containing
20000 nematode eggs near the collar region of seedlings when they grow to the eighth real leaf stage.
The experiment was conducted in a completely randomized design with 6 replications. After four
months, the hormonal content of the roots and leaves of the seedlings was assessed using a UPLC/MS
device, and the results were analyzed with SAS 9.4 software (P≤ 0.01). The results of ANOVA and
the mean comparison showed that the biosynthesis and accumulation of both jasmonic acid and
salicylic acid hormones were increased significantly in both rootstocks. However, the “Qazvini”
rootstock displayed a robust hormonal defense system, compared with the “Badami-riz” rootstock.
Indeed, the content of salicylic acid in the “Qazvini” rootstock (57.26 and 43.5 ng/g) was 40% and
64.2% higher respectively in the roots and leaves compared to “Badami-riz” rootstock (38.15 and
22.35 ng/g) roots and leaves respectively. Likewise, the accumulation of jasmonic acid in the roots
and leaves of the “Qazvini” rootstock (71.8 and 36.1 ng/g) was 41.6% and 48.4% higher than its
content in the “Badami-riz” rootstock (47.06 and 22.8 ng/g). The results showed that the
phytohormonal defense system in the “Qazvini” seedlings, which is known as an Iranian root-knot
nematode tolerant rootstock, is significantly augmented than the susceptible rootstock of the “Badami-
riz”, which can be considered an important mechanism inducing root-knot nematode tolerance in
pistachio.