[Disease resistance signal transfer between roots of different tomato plants through common arbuscular mycorrhiza networks].
Common mycorrhizal networks (CMNs) are the underground conduits of nutrient exchange between plants. However, whether the CMNs can serve as the underground conduits of chemical communication to transfer the disease resistance signals between plants are unknown. By inoculating arbuscular mycorrhizal fungus (AMF) Glomus mosseae to establish CMNs between 'donor' and 'receiver' tomato plants, and by inoculating Alternaria solani, the causal agent of tomato early blight disease, to the 'donor' plants, this paper studied whether the potential disease resistance signals can be transferred between the 'donor' and 'receiver' plants roots. The real time RT-PCR analysis showed that after inoculation with A. solani, the AMF-inoculated 'donor' plants had strong expression of three test defense-related genes in roots, with the transcript levels of the phenylalanine ammonia-lyase (PAL), lipoxygenase (LOX) and chitinase (PR3) being significantly higher than those in the roots of the 'donor' plants only inoculated with A. solani, not inoculated with both A. solani and AMF, and only inoculated with AMF. More importantly, in the presence of CMNs, the expression levels of the three genes in the roots of the 'receiver' plants were significantly higher than those of the 'receiver' plants without CMNs connection, with the connection blocking, and with the connection but the 'donor' plants not A. solani-inoculated. Compared with the control (without CMNs connection), the transcript level of the PAL, LOX and PR3 in the roots of the 'receiver' plants having CMNs connection with the 'donor' plants was 4.2-, 4.5- and 3.5-fold higher, respectively. In addition, the 'donor' plants activated their defensive responses more quickly than the 'receiver' plants (18 and 65 h vs. 100 and 140 h). These findings suggested that the disease resistance signals produced by the pathogen-induced 'donor' tomato plant roots could be transferred to the 'receiver' plant roots through CMNs.
State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources/Ministry of Agriculture Key Laboratory of Tropical Agro-environment/Institute of Tropical & Subtropical Ecology, South China Agricultural University, Guangzhou 510642, China. Xielijuntxt@yahoo.com.cn
Li-Jun
LJ
Xie
Yuan-Yuan
YY
Song
Ren-Sen
RS
Zeng
Rui-Long
RL
Wang
Xiao-Chen
XC
Wei
Mao
M
Ye
Lin
L
Hu
Hui
H
Zhang
D000528:Alternaria / Q000472:pathogenicity; D060467:Disease Resistance; D018551:Solanum lycopersicum / Q000254:growth & development / Q000382:microbiology*; D038821:Mycorrhizae / Q000378:metabolism / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control*; D018517:Plant Roots / Q000382:microbiology*; D013559:Symbiosis