Laboratoire d'adaptation des plantes aux stress abiotiques, centre de biotechnologie, technopole de Borj Cédria, BP 901, Hammam-Lif 2050, Tunisia.
C R Biol. 2010 Mar;333(3):205-13. doi: 10.1016/j.crvi.2009.12.010. Epub 2010 Mar 2.
The effects of water stress were investigated in two Tunisian Medicago truncatula populations collected from arid (Mt-173) and sub-humid (Mt-664) climates and two Tunisian M. laciniata populations originating from arid (Ml-173) and semi-arid (Ml-345) regions. After a pre-treatment phase (24 days after sowing, DAS) of watering at 100% of field capacity (FC), the plants were either irrigated at 100% FC or at only 33% FC. After 12 days of treatment (36 DAS), one lot of dehydrated plants was rewatered at 100% FC. A final harvest was carried out after 24 days of treatment (48 DAS). Measured parameters were total dry weight (TDW), root shoot ratio (RSR), leaf relative water content (RWC), osmotic potential (OP), photosynthetic parameters (CO(2) net assimilation A, stomatal conductance g(s) and transpiration E), malondialdehyde (MDA) concentration and leaf contents in inorganic (Na(+) and K(+)) and organic solutes (proline and soluble sugars). Under water deficit conditions, compared to M. laciniata, M. truncatula populations showed a higher reduction in TDW, A, g(s) and RWC associated with a higher increase in MDA concentration. Thus, the relative tolerance of M. laciniata populations to water shortage would be related to their lower intrinsic growth rate and stomatal control of gas exchange. TDW, A, g(s), E and RWC were more decreased by water deficit in Ml-345 than in Ml-173. Drought tolerance of Ml-173 was found to be associated with a more pronounced decrease of OP and a lower reduction in RWC due to the accumulation of solutes such as proline, soluble sugars and K(+). In addition, Ml-173 showed the highest water use efficiency values (WUE) and the lowest MDA concentrations under water deficit stress.
研究了来自干旱（Mt-173）和亚湿润（Mt-664）气候的两个突尼斯蒺藜苜蓿群体以及来自干旱（Ml-173）和半干旱（Ml-345）地区的两个突尼斯 M. laciniata 群体的水分胁迫效应。在播种后 24 天（24 DAS）的预处理阶段，对植物进行了 100%田间持水量（FC）的浇水，然后对植物进行 100% FC 或 33% FC 的灌溉。在 12 天的处理（36 DAS）后，一批脱水植物重新浇 100% FC。在处理 24 天后（48 DAS）进行最后一次收获。测量的参数包括总干重（TDW）、根冠比（RSR）、叶片相对含水量（RWC）、渗透势（OP）、光合参数（CO（2）净同化 A、气孔导度 g（s）和蒸腾 E）、丙二醛（MDA）浓度和叶片中的无机（Na（+）和 K（+））和有机溶质（脯氨酸和可溶性糖）含量。在水分亏缺条件下，与 M. laciniata 相比，M. truncatula 种群的 TDW、A、g（s）和 RWC 降低幅度更大，MDA 浓度升高幅度更大。因此，M. laciniata 种群对水分短缺的相对耐受性与它们较低的内在生长率和气孔对气体交换的控制有关。在 Ml-345 中，TDW、A、g（s）、E 和 RWC 受水分亏缺的影响比在 Ml-173 中更大。发现 Ml-173 的耐旱性与 OP 更明显降低以及由于脯氨酸、可溶性糖和 K（+）等溶质的积累导致 RWC 降低幅度较小有关。此外，Ml-173 在水分胁迫下表现出最高的水分利用效率值（WUE）和最低的 MDA 浓度。
