Genomic analysis of allelopathic response to low nitrogen and barnyardgrass competition in rice (Oryza sativa L.)

Agroecological Institute/School of Life Sciences, Fujian Agriculture and Forestry University (FAFU), 350002 Fuzhou, People’s Republic of China
Plant Growth Regulation (Impact Factor: 1.63). 07/2010; 61(3):277-286. DOI: 10.1007/s10725-010-9475-8

ABSTRACT To explore the molecular mechanism of allelopathic rice in response to low nitrogen (N) supply or accompanying weed stress,
allelopathic rice PI 312777 and its counterpart Lemont were grown under low N supply or co-cultured with barnyardgrass [Echinochloa crus-galli (L.) Beauv.] in hydroponics. The suppression subtractive hybridization (SSH) technique was employed to isolate the up-regulated
genes in the treated rice accession. The results indicated that the expression of the genes associated with N utilization
was significantly up-regulated in allelopathic rice PI 312777, and the higher efficiency of N uptake and its utilization were
also detected in PI 312777 than that in Lemont when the two rice accessions were exposed to low N supply. This result suggested
that the allelopathic rice had higher ability to adapt to low N stress than its non-allelopathic counterpart. However, a different
response was observed when the allelopathic rice was exposed to accompanying weed (barnyardgrass) co-cultured in full Hoagland
solution (normal N supply). It showed that the expression of the genes associated with allelochemical synthesis and its detoxification
were all up-regulated in the allelopathic rice when co-cultured with the target weed under normal N supply. The results suggested
that the allelopathic rice should be a better competitor in the rice-weed co-culture system, which could be attributed to
increasing de novo biosynthesis and detoxification of allelochemicals in rice, consequently resulting in enhanced allelopathic
effect on the target and preventing the autotoxicity in this process. These findings suggested that the accompanying weed,
barnyardgrass is not only the stressful factor, but also one of the triggers in activating allelopathy in rice. This implies
that the allelopathic rice is sensible of the existing target in chemical communication.

KeywordsAllelopathy-Barnyardgrass-Gene expression-Low nitrogen-Plant defense-Rice

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