Council for Agricultural Research and Economics, Research Centre for Cereal and Industrial Crops, S.S. 673 Km 25,200, 71122, Foggia, Italy.
Palazzo Sistemi Elettronici (PSE) S.r.l., Via Mione, 39, 71122, Foggia, Italy.
BMC Plant Biol. 2019 Oct 7;19(1):411. doi: 10.1186/s12870-019-1987-4.
The presence and persistence of water on the leaf can affect crop performance and thus might be a relevant trait to select for or against in breeding programmes. Low-cost, rapid and relatively simple methods are of significant importance for screening of large populations of plants for moisture analysis of detached leaves. Leaf moisture can be detected using an electric circuit, where the resistance changes are proportional to the moisture of the measured surface. In this study, we present a protocol to analyse genotypic differences through the electrical properties of living or stored tissues, performed using a commercial device. Expanded and non-expanded leaves were compared to determine the effects of leaf maturity on these data. Two wheat genotypes that differ in tissue affinity for bound water were used to define the influence of water status.
The device indirectly estimates leaf moisture content using two electrodes applied to the leaf lamina of fresh and stored samples. Single moisture readings using this moisture meter had mean execution time of ~ 1.0 min. Exponential associations provided good fits for relationships between the moisture meter reading (MMR) and the electrical resistance applied to the electrodes. MMR normalised for the water/ dry matter ratio (MMRnorm) was lower for mature leaves of the water-mutant than those of wild-type, for the fully hydrated fresh leaves. MMR of fully mature leaves when partially dehydrated and measured after 10 min at 27 °C and 40% relative humidity was greater for the water-mutant than the wild-type.
This case study provides a low-cost tool to compare electrical-resistance estimates of leaf moisture content, together with a promising and rapid phenotyping protocol for genotypic screening of wheat under standard environmental conditions. Measurement of changes in MMR with time, of fresh and partially dehydrated leaves, or of MMR normalised to tissue water content allowed for differentiation between the genotypes. Furthermore, the differences observed between genotypes that here relate particular to tissue affinity for bound water suggest that not only the free-water fraction, but also other water fractions, can affect these electrically estimated leaf moisture measures.
叶片上水的存在和持续时间会影响作物的性能，因此在育种计划中选择或反对可能是一个相关的特征。对于从大量植物中筛选用于叶片水分分析的低成本、快速和相对简单的方法具有重要意义。可以使用电路检测叶片水分，其中电阻变化与测量表面的水分成正比。在这项研究中，我们提出了一种使用商业设备分析活体或储存组织电特性的基因型差异的方案。比较展开和未展开的叶片，以确定叶片成熟度对这些数据的影响。使用两种对结合水亲和力不同的小麦基因型来定义水状态的影响。
该设备通过施加到新鲜和储存样本叶片叶表皮的两个电极间接估计叶片的水分含量。使用该水分计进行单次水分读数的平均执行时间约为 1.0 分钟。水分计读数（MMR）与施加到电极的电阻之间的指数关系提供了很好的拟合。对于完全水合的新鲜叶片，成熟叶片的 MMR 归一化与水分/干物质比（MMRnorm）比野生型低。当完全成熟的叶片部分脱水并在 27°C 和 40%相对湿度下测量 10 分钟后，水分突变体的 MMR 比野生型高。
本案例研究提供了一种低成本的工具，用于比较叶片水分含量的电阻估计值，并提供了一种有前途的快速表型筛选协议，用于在标准环境条件下对小麦进行基因型筛选。测量新鲜和部分脱水叶片的 MMR 随时间的变化，或 MMR 归一化到组织水分含量，可区分基因型。此外，观察到的基因型之间的差异，特别是与结合水亲和力相关的差异，表明不仅自由水部分，而且其他水部分，都可以影响这些电估计的叶片水分测量值。
