摘要
以黑麦草为实验对象 ,研究了干旱胁迫条件下内生真菌感染对植株叶片含水量和叶内游离脯氨酸含量的影响 ,同时对渗透胁迫条件下植株叶内 ABA含量的变化进行了分析。结果表明 :1内生真菌的感染有助于使叶片保持较高的含水量 ;2在两种形式的水分胁迫下 ,前期至中期高感染种群的叶片游离脯氨酸含量低于低感染种群 ,而在末期则有高出低感染种群的趋势 ;3内生真菌感染对黑麦草叶内
Endophytes or Endophytic fungi are a kind of fungi that live inside plant. They widely exist in higher plants, particularly in grasses. The fungi are members of class Ascomycetes, family Clavicipitaceae, tribe Balansiae, including some imperfect fungi that are in close relationship with tribe Balansiae, such as fungi of Acremonium. It has been well documented that endophytes and their host plants are mutually symbiotic. On one hand, plants provide photosynthates for the fungi; on the other hand, endophytes may enhance the host's growth and resistance to abiotic stresses (such as drought, high temperature) and biotic stresses (such as herbivore graze).Although the mechanisms of how endophytes enhance the drought resistance of host plant are still unknown, it is clear that endophytes benefit their host through affecting its substance metabolism, or through producing physiologically activated substances (i.e. alkaloid, hormone). Some researchers have found that the infected plants have greater ability of osmotic regulation, so as to maintain a higher turgor pressure and thus keep growing under water stress. Most of these studies, however, were focused on polyols. Two important molecules in osmotic regulation, proline and ABA, have seldom been mentioned. A comparative study of HI (highly-infected) and LI (low-infected) populations were conducted under two different water stress conditions. Physiological characteristics related to drought resistance of plants, including leaf water content (LWC), free proline content and abscisic acid (ABA) content, were determined.. Seeds of Lolium perenne\% cv Pinnacle (from Oregon Seed Company, USA) were treated in two different ways: some were placed on moist filter paper and germinated under room temperature to get HI plants, others were exposed to heat treatment in bath (43℃15min, then 57℃ 35min) and then placed on moist filter paper to get LI plants. The experiment was conducted on the campus of Nankai University, Tianjin, China. There were 18 plots, 40cm×50cm in size each, and 15cm wide interspaces between plots. HI and LI seedlings were transplanted into each of the nine plots, respectively. The drought stress (without watering) was imposed to the plots from September 18 to September 30, 1999, and the plots were fully watered a week before the experiment started. HI and LI plants were transplanted into culture pot, which was filled with 500ml 1/2 Hoagland solution. One week later, osmoticum (PEG6000) was added to impose osmotic stress (control, mild stress and severe stress). PEG content for the above stresses is 0%, 10%, 20%, respectively. Newly expanded leaves were taken for the determination of water content, free proline and ABA concentration. In field experiment, leaf samples were taken between 2:30 and 3:00 pm on daily basis or at 3～4 day intervals. In PEG osmotic stress experiment, the sampling work was carried out between 9:00 and 9:30 am at 1～3 day intervals. Immediately after leaf blade was cut off the plant, the sample was taken to laboratory and fresh weight was measured. The sample was then placed in an oven at 105℃ for a quick termination of enzyme activity before it was kept at 60℃ for 24h, and then the dry weight was measured. Proline was determined following the procedure by Zhang DZ et al\%. (1990). ABA concentration of leaf was determined with ELISA and the kits were purchased from Nanjing Agricultural University, China. The soil water content (SWC) and leaf water content (LWC) decreased progressively during drought stress. The LWC of both HI and LI plants changed in similar way, but the LWC of HI plants was higher in the middle and later stages of stress, which indicated that HI plants could maintain higher LWC under prolonged water stress. The SWC and LWC of plants were positively correlated (correlation equations are as follows: HI\ y 1=0.6509x 1+0.6796, r 1=0.78, P<0.01; LI\ y 2=0.9493x 2+0.6254, r 2=0.79,P<0.01). The changes of proline concentration of HI and LI plants were similar and both showed a wave -like increase. After two wa
出处
《生态学报》
CAS
CSCD
北大核心
2001年第12期1964-1972,共9页
Acta Ecologica Sinica
基金
国家重点基础研究发展规划项目 (编号 G2 0 0 0 0 1 86 0 1 )
国家自然科学基金 (编号 39870 1 4 2 )资助项目
