School of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 701-702, Korea.
J Microbiol Biotechnol. 2011 Sep;21(9):893-902. doi: 10.4014/jmb.1103.03012.
Endophytic fungi are little known for their role in gibberellins (GAs) synthesis and abiotic stress resistance in crop plants. We isolated 10 endophytes from the roots of field-grown soybean and screened their culture filtrates (CF) on the GAs biosynthesis mutant rice line - Waito-C. CF bioassay showed that endophyte GMH-1B significantly promoted the growth of Waito-C compared with controls. GMH-1B was identified as Penicillium minioluteum LHL09 on the basis of ITS regions rDNA sequence homology and phylogenetic analyses. GC/MS-SIM analysis of CF of P. minioluteum revealed the presence of bioactive GA(4) and GA(7). In endophyte-soybean plant interaction, P. minioluteum association significantly promoted growth characteristics (shoot length, shoot fresh and dry biomasses, chlorophyll content, and leaf area) and nitrogen assimilation, with and without sodium chloride (NaCl)-induced salinity (70 and 140 mM) stress, as compared with control. Field-emission scanning electron microcopy showed active colonization of endophyte with host plants before and after stress treatments. In response to salinity stress, low endogenous abscisic acid and high salicylic acid accumulation in endophyte-associated plants elucidated the stress mitigation by P. minioluteum. The endophytic fungal symbiosis of P. minioluteum also increased the daidzein and genistein contents in the soybean as compared with control plants, under salt stress. Thus, P. minioluteum ameliorated the adverse effects of abiotic salinity stress and rescued soybean plant growth by influencing biosynthesis of the plant's hormones and flavonoids.
内生真菌在赤霉素（GA）合成和作物抗非生物胁迫方面的作用鲜为人知。我们从田间生长的大豆根系中分离出 10 种内生真菌，并在赤霉素生物合成突变体水稻系 - Waito-C 上筛选其培养滤液（CF）。CF 生物测定表明，内生真菌 GMH-1B 与对照相比，显著促进了 Waito-C 的生长。根据 ITS 区 rDNA 序列同源性和系统发育分析，GMH-1B 被鉴定为 Penicillium minioluteum LHL09。CF 的 GC/MS-SIM 分析表明存在生物活性 GA(4)和 GA(7)。在内生菌-大豆植物相互作用中，与对照相比，P. minioluteum 关联显著促进了生长特性（茎长、茎鲜重和干重、叶绿素含量和叶面积）和氮同化，无论是否存在氯化钠（NaCl）诱导的盐度（70 和 140 mM）胁迫。场发射扫描电子显微镜显示，内生菌在胁迫处理前后与宿主植物的积极定殖。对盐胁迫的响应，内生菌相关植物中低内源脱落酸和高水杨酸积累阐明了 P. minioluteum 的胁迫缓解作用。与对照植物相比，盐胁迫下内生真菌 P. minioluteum 的共生也增加了大豆中的大豆苷元和染料木黄酮含量。因此，P. minioluteum 通过影响植物激素和类黄酮的生物合成，减轻了非生物盐胁迫的不利影响，并挽救了大豆植物的生长。
