Meuriot Frédéric, Noquet Carine, Avice Jean-Christophe, Volenec Jeffrey J., Cunningham Suzanne M., Sors Thomas G., Caillot Sébastien, Ourry Alain
UMR INRA UCBN 950 Physiologie et Biochimie Végétales, Institut de Recherche en Biologie Appliquée, Université, 14032 Caen Cedex, France Department of Agronomy, Purdue University, West Lafayette, IN 47907-1150, USA.
Physiol Plant. 2004 Jan;120(1):113-123. doi: 10.1111/j.0031-9317.2004.0210.x.
This study presents the effects of methyl jasmonate (MeJA) on growth, N uptake, N partitioning, and N storage in taproots of non-nodulated alfalfa (cv. Lodi). When compared to untreated plants, addition of 100 micro M MeJA to the nutrient solution for 14 days reduced total growth and modified biomass partitioning between shoots and roots in favour of taproots and lateral roots. MeJA decreased N uptake (after 7 days) and increased N partitioning towards roots after 14 days. This preferential N partitioning to roots was accompanied by increased N storage in taproots as soluble proteins. Compared to total soluble proteins, VSP accumulation occurred earlier (7 days), and was greater (2-fold increase) in plants treated with 100 micro M MeJA. Steady-state transcript levels for two VSPs (32 and 57 kDa) also increased markedly (about 4-fold) in roots of plants treated with 100 micro M MeJA. This suggests that MeJA could act directly (transcriptional regulation) or indirectly (via the changes of N partitioning among alfalfa organs) on N storage as soluble proteins and in particular, VSPs. Because the deduced amino acid sequence of the 32 kDa VSP clone reveals high homology with Class III chitinases, we propose that the 32 kDa VSP may have a role in pathogen defense, in addition to its function as a storage protein.
本研究展示了茉莉酸甲酯（MeJA）对未结瘤紫花苜蓿（品种洛迪）主根生长、氮吸收、氮分配和氮储存的影响。与未处理的植株相比，在营养液中添加100微摩尔的MeJA并持续14天，会降低总生长量，并改变地上部和根部之间的生物量分配，有利于主根和侧根。MeJA降低了氮吸收（7天后），并在14天后增加了向根部的氮分配。这种向根部的优先氮分配伴随着主根中作为可溶性蛋白质的氮储存增加。与总可溶性蛋白质相比，VSP积累出现得更早（7天），并且在100微摩尔MeJA处理的植株中更大（增加了2倍）。在100微摩尔MeJA处理的植株根部，两种VSP（32 kDa和57 kDa）的稳态转录水平也显著增加（约4倍）。这表明MeJA可以直接（转录调控）或间接（通过苜蓿器官间氮分配的变化）作用于作为可溶性蛋白质尤其是VSP的氮储存过程。由于32 kDa VSP克隆的推导氨基酸序列与III类几丁质酶具有高度同源性，我们推测32 kDa VSP除了作为储存蛋白的功能外，可能在病原体防御中发挥作用。
