| A decrease in the ozone layer could lead to a significant increase in ultraviolet-B (UV-B) radiation (280-320nm) reaching the earth’s surface. Recently an "ozone hole" has been discovered above the Qinghai-Tibet Plateau inChina. In order to examine the effects of the enhanced UV-B radiation on the growth and reproduction of the alpine species on Qinghai-Tibet Pleteau, we use wild legume forages-Vicia unijuga A as research materials in laboratory conditions with the UV-B radiation level was6.4K.J.m-2.d-1(simulating a9%ozone depletion over Gannan,China34。55’N,2900m). The growth and development, physiology and biochemistry, gene expression under UV-B radiation were explored in this study. The plant height, aboveground biomass, leaf area, endogenous hormones, plant nutrients, lignin synthesis-related gene expression levels and other indicators were measured. The results showed:1) Enhanced UV-B radiation made the leafes of Vicia unijuga A skew, asymmetries, brown spots on the surface, and lignin deposition thickened in stems. In the central of stem, the medullary cavity was increase.2) A short time of enhanced UV-B treatment (10days) had no significant effect in plant height and aboveground biomass of Vicia unijugaA, with the accumulation of UV-B treatment time and the amount of radiation, they was lower than that of the control group significantly. Early UV-B radiation treatment has a stronger inhibitory effect on the growth of root of Vicia unijuga A, in the later period, it was the root growth frist. And UV-B radiation reduced the leaves area of Vicia unijuga A significantly.3) In10days of UV-B treatment, the plant endogenous hormones ZT,6-BA, GAs, IAA were higher than the control group significantly.10days later, the content of them were decreased rapidly and significantly lower than the control group with the irradiation time. Changes in the content of GAs and IAA were most dramatic. UV-B treatment increased the ABA content significantly.4) Total nitrogen content was higher than that of the control group in the first10days, but with the time extension of UV-B treatment, the rate of decline of total nitrogen is faster than the control group, which indicated that UV-B irradiation accelerated the consumption of plant total nitrogen. The content of organic carbon was higher than the control group significantly in the first10days of UV-B irradiation treatment, after which, the content was no significant difference between the control group. The content of total phosphorus is consistent with the changes in the content of organic carbon, which showed that the content of organic carbon and nitrogen of Vicia unijuga A have a less affected by UV-B irradiation enhanced.5) In the whole process of UV-B radiation, the express of CAD gene was lower than the control group, the expression is suppressed, it’s more sensitive to UV-B radiation. Despite the express of F5H gene has an increase in the whole process of the UV-B, compared to the expression level of the control group, it’s still suppressed. Gene expression of CCOAOMT in the whole process of UV-B radiation presents a rising trend, which shows that the gene is susceptible to UV-B radiation excited, and it is the key gene in lignin synthesis.At the same time, we constructed a full-length cDNA Library of Vicia unijuga A by SMART technique. According to the evaluation on quality, The titer of primary library was2.3×106pfu·mL-1, while the amplified library has a high titer of6.2×109pfu·mL-1and92.7%recombinant percentage.16plaques were randomly picked from the amplified library, after amplified by PCR identification, the results showed that the inserted fragment is mostly distributed between500to2500bp. The3’end full-length cDNA of CAD, a Vicia unijuga A gene related with lignin synthesis cloned by RACE method in the past, was amplified in this cDNA Library by PCR, which indicated that the cDNA library for leaves of Vicia unijuga had been constructed successfully by using the SMART technique. |
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