JOil (S) Pte Ltd, 1 Research Link, Singapore 117604.
BMC Plant Biol. 2010 Nov 23;10:259. doi: 10.1186/1471-2229-10-259.
There is a growing interest in Jatropha curcas L. (jatropha) as a biodiesel feedstock plant. Variations in its morphology and seed productivity have been well documented. However, there is the lack of systematic comparative evaluation of distinct collections under same climate and agronomic practices. With the several reports on low genetic diversity in jatropha collections, there is uncertainty on genetic contribution to jatropha morphology.
In this study, five populations of jatropha plants collected from China (CN), Indonesia (MD), Suriname (SU), Tanzania (AF) and India (TN) were planted in one farm under the same agronomic practices. Their agronomic traits (branching pattern, height, diameter of canopy, time to first flowering, dormancy, accumulated seed yield and oil content) were observed and tracked for two years. Significant variations were found for all the agronomic traits studied. Genetic diversity and epigenetic diversity were evaluated using florescence Amplified Fragment Length Polymorphism (fAFLP) and methylation sensitive florescence AFLP (MfAFLP) methods. Very low level of genetic diversity was detected (polymorphic band <0.1%) within and among populations. In contrast, intermediate but significant epigenetic diversity was detected (25.3% of bands were polymorphic) within and among populations. More than half of CCGG sites surveyed by MfAFLP were methylated with significant difference in inner cytosine and double cytosine methylation among populations. Principal coordinates analysis (PCoA) based on Nei's epigenetic distance showed Tanzania/India group distinct from China/Indonesia/Suriname group. Inheritance of epigenetic markers was assessed in one F1 hybrid population between two morphologically distinct parent plants and one selfed population. 30 out of 39 polymorphic markers (77%) were found heritable and followed Mendelian segregation. One epiallele was further confirmed by bisulphite sequencing of its corresponding genomic region.
Our study confirmed climate and practice independent differences in agronomic performance among jatropha collections. Such agronomic trait variations, however, were matched by very low genetic diversity and medium level but significant epigenetic diversity. Significant difference in inner cytosine and double cytosine methylation at CCGG sites was also found among populations. Most epigenetic differential markers can be inherited as epialleles following Mendelian segregation. These results suggest possible involvement of epigenetics in jatropha development.
麻风树（Jatropha curcas L.，麻风树）作为生物柴油原料植物的兴趣日益浓厚。其形态和种子生产力的变化已有详细记录。然而，在相同的气候和农业实践下，对不同收集品系的系统比较评估却缺乏。鉴于麻风树收集品系遗传多样性较低的报道，遗传因素对麻风树形态的贡献存在不确定性。
本研究收集了来自中国（CN）、印度尼西亚（MD）、苏里南（SU）、坦桑尼亚（AF）和印度（TN）的五个麻风树种群，在同一农场按照相同的农业实践进行种植。对它们的农艺性状（分枝模式、高度、冠层直径、首次开花时间、休眠、累积种子产量和油含量）进行了两年的观察和跟踪。研究发现所有农艺性状均存在显著差异。使用荧光扩增片段长度多态性（fAFLP）和甲基化敏感荧光 AFLP（MfAFLP）方法评估了遗传多样性和表观遗传多样性。种群内和种群间的遗传多样性水平非常低（多态带<0.1%）。相比之下，种群内和种群间检测到中等但显著的表观遗传多样性（25.3%的带多态性）。通过 MfAFLP 检测到的超过一半的 CCGG 位点被甲基化，种群间的内胞嘧啶和双胞嘧啶甲基化存在显著差异。基于 Nei 的表观遗传距离的主坐标分析（PCoA）显示坦桑尼亚/印度群体与中国/印度尼西亚/苏里南群体明显不同。在两个形态上明显不同的亲本植物之间的一个 F1 杂种群体和一个自交群体中评估了表观遗传标记的遗传。在 39 个多态标记中（77%）发现了 30 个可遗传标记，遵循孟德尔分离。一个表观等位基因通过其相应基因组区域的亚硫酸氢盐测序进一步证实。
本研究证实了在麻风树收集品系中，气候和实践独立的农艺表现存在差异。然而，这种农艺性状的变化与遗传多样性非常低和中等水平但显著的表观遗传多样性相匹配。种群间 CCGG 位点的内胞嘧啶和双胞嘧啶甲基化也存在显著差异。大多数表观遗传差异标记可以作为遵循孟德尔分离的表观等位基因遗传。这些结果表明表观遗传可能参与了麻风树的发育。
