University of the Philippines Visayas Tacloban College , Tacloban City, Leyte , Philippines.
AoB Plants. 2010;2010:plq010. doi: 10.1093/aobpla/plq010. Epub 2010 Jun 29.
Purple nutsedge (Cyperus rotundus L.) is a major weed of upland crops and vegetables. Recently, a flood-tolerant ecotype evolved as a serious weed in lowland rice. This study attempted to establish the putative growth and physiological features that led to this shift in adaptation.
Tubers of upland C. rotundus (ULCR) and lowland C. rotundus (LLCR) ecotypes were collected from their native habitats and maintained under the respective growth conditions in a greenhouse. Five experiments were conducted to assess the variation between the two ecotypes in germination, growth and tuber morphology when grown in their native or 'switched' conditions. Carbohydrate storage and mobilization, and variation in anaerobic respiration under hypoxia were compared.
Tubers of LLCR were larger than those of ULCR, with higher carbohydrate content, and larger tubers developed with increasing floodwater depth. Stems of LLCR had larger diameter and proportionally larger air spaces than those of ULCR: a method of aerating submerged plant parts. The LLCR ecotype can also mobilize and use carbohydrate reserves under hypoxia, and it maintained relatively lower and steadier activity of alcohol dehydrogenase (ADH) as a measure of sustained anaerobic respiration. In contrast, ADH activity in ULCR increased faster upon a shift to hypoxia and then sharply decreased, suggesting depletion of available soluble sugar substrates. The LLCR ecotype also maintained lower lactate dehydrogenase activity under flooded conditions, which could reduce chances of cellular acidosis.
These adaptive traits in the LLCR ecotype were expressed constitutively, but some of them, such as tuber growth and aerenchyma development, are enhanced with stress severity. The LLCR ecotype attained numerous adaptive traits that could have evolved as a consequence of natural evolution or repeated management practices, and alternative strategies are necessary because flooding is no longer a feasible management option.
紫茎泽兰（Cyperus rotundus L.）是旱地作物和蔬菜的主要杂草。最近，一种耐涝生态型在水稻低地成为一种严重的杂草。本研究试图确定导致这种适应转变的潜在生长和生理特征。
从其原生境中采集旱地紫茎泽兰（ULCR）和低地紫茎泽兰（LLCR）生态型的块茎，并在温室中分别在各自的生长条件下维持。进行了五项实验，以评估在其原生或“转换”条件下生长时，两种生态型在萌发、生长和块茎形态上的差异。比较了碳水化合物的储存和动员以及缺氧下无氧呼吸的变化。
LLCR 的块茎比 ULCR 的大，碳水化合物含量更高，随着洪水深度的增加，块茎也更大。LLCR 的茎直径较大，空气空间比例较大，比 ULCR 的大：这是一种为淹没植物部分充气的方法。LLCR 生态型在缺氧条件下也可以动员和利用碳水化合物储备，并且其维持相对较低且稳定的酒精脱氢酶（ADH）活性，作为持续无氧呼吸的衡量标准。相比之下，ULCR 在转换到缺氧时 ADH 活性增加得更快，然后急剧下降，表明可用可溶性糖底物耗尽。LLCR 生态型在水淹条件下也保持较低的乳酸脱氢酶活性，这可以减少细胞酸中毒的机会。
这些 LLCR 生态型的适应性特征是组成性表达的，但其中一些特征，如块茎生长和通气组织的发育，随着胁迫的严重程度而增强。LLCR 生态型获得了许多适应性特征，这些特征可能是自然进化或反复管理实践的结果，需要采取替代策略，因为洪水不再是可行的管理选择。
