The low grain water content (GWC) at harvest is a prerequisite to mechanical harvesting in maize, or otherwise would cause massive broken kernels and increase drying costs. The GWC at harvest in turn depends on GWC at the physiological maturity (PM) stage and grain dehydration rate (GDR). Both GWC and GDR are very complex traits, governed by multiple quantitative trait loci (QTL) and easily influenced by environmental conditions. So far, a number of experiments have been conducted to reveal numbers of GWC and GDR QTL, however, very few QTL have been confirmed, and no QTL has been fine-mapped or even been cloned. We demonstrated that GWCs after PM were positively correlated with GWC at PM, whereas negatively with GDRs after PM. With a recombinant inbred line (RIL) population, we identified totally 31 QTL related to GWC and 17 QTL related to GDR in three field trials. Seven GWC QTL were consistently detected in at least two of the three field trials, each of which could explain 6.92–24.78% of the total GWC variation. Similarly, one GDR QTL was consistently detected, accounting for 9.44–14.46% of the total GDR variation. Three major GWC QTL were found to overlap with three GDR QTL in bins 1.05/06, 2.06/07, and 3.05, respectively. One of the consistent GWC QTL, namely qGwc1.1, was fine-mapped from a 27.22 Mb to a 2.05 Mb region by using recombinant-derived progeny test. The qGwc1.1 acted in a semi-dominant manner to reduce GWC by 1.49–3.31%. A number of consistent GWC and GDR QTL have been identified, and one of them, QTL-qGwc1.1, was successfully refined into a 2.05 Mb region. Hence, it is realistic to clone the genes underlying the GWC and GDR QTL and to make use of them in breeding of maize varieties with low GWC at harvest.

中文翻译：

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玉米机械收获相关籽粒含水量和脱水率的遗传解析

收获时谷物含水量（GWC）较低是玉米机械收割的先决条件，否则会导致大量碎粒并增加干燥成本。收获时的 GWC 又取决于生理成熟 (PM) 阶段的 GWC 和谷物脱水率 (GDR)。GWC和GDR都是非常复杂的性状，受多个数量性状基因座（QTL）控制，并且容易受到环境条件的影响。到目前为止，已经进行了大量的实验来揭示GWC和GDR QTL的数量，但是，被证实的QTL很少，并且没有QTL被精细定位甚至被克隆。我们证明，PM 后的 GWC 与 PM 时的 GWC 呈正相关，而与 PM 后的 GDR 呈负相关。在重组自交系（RIL）群体中，我们在三个田间试验中总共鉴定了31个与GWC相关的QTL和17个与GDR相关的QTL。三个田间试验中的至少两个一致检测到 7 个 GWC QTL，每个 QTL 都可以解释总 GWC 变异的 6.92-24.78%。同样，一致检测到一个 GDR QTL，占总 GDR 变异的 9.44-14.46%。发现三个主要 GWC QTL 分别与 bin 1.05/06、2.06/07 和 3.05 中的三个 GDR QTL 重叠。通过使用重组衍生的后代测试，一致的 GWC QTL 之一，即 qGwc1.1，从 27.22 Mb 区域精细定位到 2.05 Mb 区域。qGwc1.1以半显性方式发挥作用，使GWC降低了1.49-3.31%。已鉴定出许多一致的GWC和GDR QTL，其中之一QTL-qGwc1.1已成功细化为2.05 Mb区域。因此，克隆 GWC 和 GDR QTL 的基因并将其用于育种收获时 GWC 较低的玉米品种是现实的。