Agronomic Traits And Salt Tolerance Of Soybean-NDHB Subunit-overexpressed Rice Lines

Rice is a maj or food crop to feed more than one third population all over the word. Rice can grow normally in appropriate conditions but not under some abiotic stresses, such as high temperature, low temperature, highlight, drought and so on. Because there is a large area of saline-alkali land in the word, Salt stress is also an important limiting factor for rice growth.The defective of subunits in chloroplast NDH complex has great impact on plant growth in adverse conditions. This conclusion has been proved by many researches. However, there are only a few reports about effect of NDHB subnit on rice growth in salt stress condition.In this work, we compared Oryza sativa L. cultivar Nipponbare (WT) with two NDHB overexpressed lines (NDHB3 and NDHB4), whose NDHB gene derived from a salt-resistant wild soybean. We not only analyzed agronomic characters of WT and two overexpressed rice lines but also measured photosynthetic and fluorescence relevant parameters in both non-stress condition and 160mM salt stress condition.As an imprtant agronomic characters, the tillering and the heading stages of the overexpressed lines were both earlier than those of WT. Compared with WT, overexpressed lines had more tillers and lower plant height. Besides, panicles per plant and filled grains per ear of overexpressed lines were more than those of WT. So the overexpression of NDHB gene modified rice seed production.In non-stress condition, there were no significant differences in photosynthetic and fluorescence relevant parameters between overexpressed lines and WT. Nevertheless, when treated with 160mM NaCl, the rate of P700+ re-reduction after turning off of the far-red light in overexpressed lines was higher than that in WT, and the amplitude of the postillumination increase in Chl fluorescence was enhanced in overexpressed lines.In addition, the significant stimulation of CEF in overexpressed lines might protect PSâ…¡ from oxidative damage, thus improving the ability of salt resistance in plants.In conclusion, overexpressed NDHB of soybean in rice could affect the agronomic characters and increase net photosynthetic rate under salt stress condition. NDHB gene of soybean may play a role not only in soybean but also in other plants in enhancing the resistance of plants to salt stress.