Casarrubias-Castillo Kena, Montero-Vargas Josaphat M, Dabdoub-González Nicole, Winkler Robert, Martinez-Gallardo Norma A, Zañudo-Hernández Julia, Avilés-Arnaut Hamlet, Délano-Frier John P
Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Jalisco, Mexico.
Departamento de Investigación en Inmunogenética y Alergia, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Mexico City, Mexico.
PeerJ. 2020 Apr 16;8:e8888. doi: 10.7717/peerj.8888. eCollection 2020.
Arbuscular mycorrhizal fungi (AMF) colonization, sampled at 32-50 days post-inoculation (dpi), was significantly reduced in mutant tomato plants impaired in the ω-3 () gene that limits the generation of linolenic acid and, consequently, the wound-responsive jasmonic acid (JA) burst. Contrary to wild-type (WT) plants, JA levels in root and leaves of mutants remained unchanged in response to AMF colonization, further supporting its regulatory role in the AM symbiosis. Decreased AMF colonization in plants was also linked to alterations associated with a disrupted FAD7 function, such as enhanced salicylic acid (SA) levels and SA-related defense gene expression and a reduction in fatty acid content in both mycorrhizal roots and leaves. Transcriptomic data revealed that lower mycorrhizal colonization efficiency in mutants coincided with the modified expression of key genes controlling gibberellin and ethylene signaling, brassinosteroid, ethylene, apocarotenoid and phenylpropanoid synthesis, and the wound response. Targeted metabolomic analysis, performed at 45 dpi, revealed augmented contents of L-threonic acid and DL-malic acid in colonized roots which suggested unfavorable conditions for AMF colonization. Additionally, time- and genotype-dependent changes in root steroid glycoalkaloid levels, including tomatine, suggested that these metabolites might positively regulate the AM symbiosis in tomato. Untargeted metabolomic analysis demonstrated that the tomato root metabolomes were distinctly affected by genotype, mycorrhizal colonization and colonization time. In conclusion, reduced AMF colonization efficiency in mutants is probably caused by multiple and interconnected JA-dependent and independent gene expression and metabolomic alterations.
丛枝菌根真菌（AMF）的定殖情况在接种后32 - 50天进行采样，在ω-3（）基因受损的突变番茄植株中显著降低，该基因限制了亚麻酸的生成，进而限制了创伤响应茉莉酸（JA）的爆发。与野生型（WT）植株相反，突变体植株根和叶中的JA水平在AMF定殖时保持不变，这进一步支持了其在丛枝菌根共生中的调节作用。突变体植株中AMF定殖的减少也与FAD7功能破坏相关的变化有关，如水杨酸（SA）水平升高、SA相关防御基因表达增强以及菌根化根和叶中脂肪酸含量降低。转录组数据显示，突变体中较低的菌根定殖效率与控制赤霉素和乙烯信号传导、油菜素内酯、乙烯、类胡萝卜素和苯丙烷合成以及创伤响应的关键基因表达改变相吻合。在接种后45天进行的靶向代谢组分析显示，定殖的突变体根中L-苏糖酸和DL-苹果酸含量增加，这表明不利于AMF定殖。此外，根中甾体糖生物碱水平（包括番茄碱）随时间和基因型的变化表明，这些代谢产物可能对番茄中的丛枝菌根共生起正向调节作用。非靶向代谢组分析表明，番茄根代谢组明显受基因型、菌根定殖和定殖时间的影响。总之，突变体中AMF定殖效率降低可能是由多种相互关联的依赖JA和不依赖JA的基因表达及代谢组改变引起的。
