Tejeda-Sartorius Miriam, Martínez de la Vega Octavio, Délano-Frier John Paul
Unidad de Biotecnología e Ingeniería Genética de Plantas (Cinvestav-Campus Guanajuato), Km 9.6 del Libramiento Norte Carretera Irapuato-León, Apartado Postal 629, C.P. 36821, Irapuato, Guanajuato, México.
Physiol Plant. 2008 Jun;133(2):339-53. doi: 10.1111/j.1399-3054.2008.01081.x. Epub 2008 Mar 5.
The role of jasmonic acid (JA) on mycorrhizal colonization by Glomus fasciculatum in tomato plants was examined using mutant plants overexpressing prosystemin (PS) or affected in the synthesis of JA (suppressor of prosystemin-mediated responses 2, spr2). The degree of mycorrhizal colonization was determined by measuring frequency (F%) and intensity (M%) of colonization and arbuscule abundance (A%). Gene expression and biochemical analyses were also performed in roots to detect changes in carbon (C) partitioning. Colonization was similar in mycorrhizal PS and wild-type roots, except for a higher A% in the former. Conversely, colonization was severely reduced in roots of spr2 mutants. No association was found between levels of expression of genes coding for systemic wound responsive proteins (or SWRPs) and other defense-related proteins in roots and mycorrhization levels in these plants. On the other hand, the degree of mycorrhizal colonization correlated with changes in the transcriptional regulation of a number of genes involved in sucrose hydrolysis and transport, cell wall invertase activity and mycorrhizal-specific fatty acid content in roots. The results obtained suggest that one of the mechanisms by which JA might operate to modulate the mycorrhization process could be through its influence on the regulation of C partitioning in the plant. The significant colonization increase observed in mycorrhizal spr2 plants supplied with exogenous methyl jasmonate supports its role as a positive regulator of the symbiosis.
利用过表达系统素（PS）的突变体植株或茉莉酸（JA）合成受影响的植株（系统素介导反应抑制因子2，spr2），研究了JA在丛枝菌根真菌（Glomus fasciculatum）对番茄植株菌根定殖中的作用。通过测量定殖频率（F%）、定殖强度（M%）和丛枝丰度（A%）来确定菌根定殖程度。还对根系进行了基因表达和生化分析，以检测碳（C）分配的变化。菌根PS植株和野生型植株的定殖情况相似，只是前者的A%较高。相反，spr2突变体植株的根系定殖严重减少。在这些植株中，根系中编码系统创伤反应蛋白（或SWRP）和其他防御相关蛋白的基因表达水平与菌根化水平之间没有关联。另一方面，菌根定殖程度与根系中一些参与蔗糖水解和运输、细胞壁转化酶活性以及菌根特异性脂肪酸含量的基因转录调控变化相关。所得结果表明，JA调节菌根化过程的机制之一可能是通过其对植物中C分配调控的影响。在供应外源茉莉酸甲酯的菌根spr2植株中观察到的显著定殖增加支持了其作为共生正调控因子的作用。
