IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

17 th International Congress on Nitrogen Fixation
Fremantle, Western Australia
27 November – 1 December 2011
Title Rice growth promotion after inoculation of Sinorhizobium melilotii 1021 and its mechanism
Authors Mingfeng Yang, Wenpeng Zhang, Shihua Shen and Yuxiang Jing
Poster Board Number 9
Key Laboratory of Plant Resource Research and Development, the Chinese Academy of
Sciences, Beijing 100093, China.
The studies have shown that the endophytic association of rhizobia with non-legumes, such as rice, wheat,
maize, rape, lettuce, etc is of benefit to their growth with increased grains or/and biomass. Our previous study
indicated that the bacteria of Sinorhizobium melilotii 1021, etc which were inoculated to rice seedlings not only
entered into root interior through lateral root emergence and root hairs, but also ascended into stem base, leave
shealth and leaves where they developed high population. Finally, they made rice increase its biomass and
grains (Chi F. et al, 2005). Recently, we found the key point time that the rice seedlings inoculated with rhizobia
grew more significantly than the controls based on rice morphology was at 5 days postinoculation(dpi). The
observation under laser confocal microscope pointed out that the gfp-tagged rhizobia moved so fast that they
arrived in rice leaves at the 5-8 dpi, and located in the intercellular space, and some of them even got into
diachyma cells after isolation of leaf cell protoplasm. Microarray-gene chip and quantitative real-time PCR
determined the gene expression of rice seedlings, showing that the related genes of DNA replication, cell division
and cell wall formation, etc were up-reguated at 2 dpi, then some of photosynthetic genes, carbohydrate
anabolism genes, defense and resistant genes were also up-regulated at 5, 8 dpi. These results indicate the
molecular basis and the mechanism that the rhizobia could promote rice growth. The following step in future is to
look for the reasons of molecular interaction between rhizobia and rice plants through metabolomics.
Feng Chi, Shi-Hua Shen, Hai-Ping Cheng, Yu-Xiang Jing,* Youssef G. Yanni, and Frank B. Dazzo. Ascending
Migration of Endophytic Rhizobia, from Roots to Leaves, inside Rice Plants and Assessment of Benefits to Rice
Growth Physiology. AEM, 2005, 71: 7271–7278.
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