Screening And Expression Analysis Of Genes Response To Aluminum Stress In Leaves Of Yunnan Faba Bean

Aluminum (Al) toxicity is one of the major factors limiting the growth of plants in acidic soils. China is an agricultural country with lots of red soils which contain Al. It is very important to explore the mechanism of plant to tolerance Al toxicity. Faba bean is a nutrient-rich plant protein resource next to soybean, which is also an important food, vegetable, subsidiary food and green manure. China is the largest faba bean cultivation country in the world and Yunnan is the largest faba bean cultivation province in China. In recent years, the cultivated area of faba beans in Yunnan province increased rapidly, however, growth of faba bean was affacted by acid soil. Therefore, it is fundamental to explore the effect of Al toxicity on faba bean and the effective way of faba bean to alleviate Al toxicity. Our previous research confirmed that faba bean varietie 83324 in Yunnan Province was an Al-tolerant species. In this study, the mechanism of faba bean 83324 to Al toxicity was investigated. The main results were as follows:1. The effect of Al toxicity on the leaves of faba bean was studied with the hydrobonic growth seedlings. The results showed that malondialdehyde (MDA) content, hydrogen peroxide (H2O2) content, protein carbonyl (PC) content increased with the same trends after different time treatments. Total protein content decreased after 12 h treatment and then decaresed but the content was lower than the plants without Al toxicity in leaves of faba bean. Soluble sugar content increased in 12 h treatment and then decaresed gradually, but the content was higher than the control without Al treatment. With the increasing of Al stress treatment time, the stomatal conductance of the faba bean leaves decreased in the same time period compared to the control without treatment. The ratio of length to width of the stoma in the leaves was higher of the Al stress treatment plants than the control.2. A suppression subtractive hybridization (SSH) library was constructed of faba bean leaves after 50μM and 100μM Al stress treatments for 12,24,48 and 72 h as tester, and leaves without Al treatments of the same time were as driver. After sequenced and Blast in the NCBI database, we got 222 ESTs, of which 198 ESTs have known function and 24 ESTs have unknown function. The 198 ESTs with known function were categorized into 8 groups, i.e., metabolism (52), photosynthesis (36), protein metabolism (28), transcript and signal transduction (25), defense and cell death (20), transport (12), energy (10) as well as cell structure and growth (7), accounted for 26%,18%,14%,13%,10%,6%,5% and 4%, respectively.3. RT-PCR analysis was done for the randomly selected genes to verify the results of SSH cDNA subtractive library. The expression of the light-harvesting chloroplast a/b protein complex, malate dehydrogenase, citrate synthase, ABC1 family protein, peroxidase, 1,5-bisphosphate carboxylase ribulose, sedoheptulose 1,7-bis phosphatase was up regulated after 50μM and 100μM Al stress treatments.