Postgrado en Botánica, Colegio de Postgraduados, Carretera México-Texcoco, Km 36.5, Montecillo, México, 56230, Mexico.
Postgrado en Botánica, Colegio de Postgraduados, Carretera México-Texcoco, Km 36.5, Montecillo, México, 56230, Mexico.
Plant Physiol Biochem. 2015 Nov;96:29-37. doi: 10.1016/j.plaphy.2015.07.006. Epub 2015 Jul 13.
In this study, we examined the effects of water deficit on the elongation of radicles of maize seedlings and on the accumulation of solutes in the radicle apices of two maize varieties: VS-22 (tolerant) and AMCCG-2 (susceptible). Sections of radicle corresponding to the first 2 mm of the primary roots were marked with black ink, and the seedlings were allowed to grow for 24, 48, and 72 h in polyvinyl chloride (PVC) tubes filled with vermiculite at three different water potentials (Ψ(w), -0.03, -1.0, and -1.5 MPa). The radicle elongation, sugar accumulation, and proline accumulation were determined after each of the growth periods specified above. The Ψ(w) of the substrate affected the dynamics of primary root elongation in both varieties. In particular, the lowest Ψ(w) (-1.5 MPa) inhibited root development by 72% and 90% for the VS-22 and AMCCG-2 varieties, respectively. The osmotic potential (Ψ(o)) was reduced substantially in both varieties to maintain root turgor; however, VS-22 had a higher root turgor (0.67 MPa) than AMCCG-2 (0.2 MPa). These results suggest that both varieties possess a capacity for osmotic adjustment. Sugar began to accumulate within the first 24 h of radicle apex growth. The sugar concentration was higher in VS-22 root apices compared to AMCCG-2, and the amount of sugar accumulation increased with a decrease in Ψ(w). Significant amounts of trehalose accumulated in VS-22 and AMCCG-2 (29.8 μmol/g fresh weight [FW] and 5.24 μmol/g FW, respectively). Starch accumulation in the root apices of these two maize varieties also differed significantly, with a lower level in VS-22. In both varieties, the proline concentration also increased as a consequence of the water deficit. At 72 h, the proline concentration in VS-22 (16.2 μmol/g FW) was almost 3 times greater than that in AMCCG-2 (5.19 μmol/g FW). Trehalose also showed a 3-fold increase in the tolerant variety. Accumulation of these solutes in the root growth zone may indicate an osmotic adjustment (OA) to maintain turgor pressure.
在这项研究中，我们研究了水分亏缺对玉米幼苗胚根伸长和两种玉米品种胚根顶端溶质积累的影响：VS-22（耐）和 AMCCG-2（敏感）。用黑色墨水标记与主根前 2 毫米相对应的胚根部分，将幼苗在填充有珍珠岩的聚氯乙烯（PVC）管中生长 24、48 和 72 小时，在三个不同的水势（Ψ（w），-0.03、-1.0 和-1.5 MPa）下。在上述每个生长阶段后，测定胚根伸长、糖积累和脯氨酸积累。基质的 Ψ（w）影响了两种品种的主根伸长动态。特别是，最低的 Ψ（w）（-1.5 MPa）分别抑制了 VS-22 和 AMCCG-2 品种的根发育 72%和 90%。两种品种的渗透势（Ψ（o））都大幅降低，以维持根膨压；然而，VS-22 的根膨压（0.67 MPa）高于 AMCCG-2（0.2 MPa）。这些结果表明，两种品种都具有渗透调节能力。糖在胚根顶端生长的前 24 小时内开始积累。VS-22 根顶端的糖浓度高于 AMCCG-2，随着 Ψ（w）的降低，糖积累量增加。在 VS-22 和 AMCCG-2 中积累了大量的海藻糖（分别为 29.8 μmol/g 鲜重[FW]和 5.24 μmol/g FW）。这两个玉米品种根顶端的淀粉积累也有显著差异，VS-22 中的淀粉水平较低。在这两个品种中，脯氨酸浓度也随着水分亏缺而增加。在 72 小时时，VS-22 中的脯氨酸浓度（16.2 μmol/g FW）几乎是 AMCCG-2（5.19 μmol/g FW）的 3 倍。在耐品种中，海藻糖也增加了 3 倍。在根生长区积累这些溶质可能表明渗透压调节（OA）以维持膨压。
