Abstract

Heterosis has been widely exploited in plants and animals, and also revolutionized agriculture by improving important agronomic traits. However, the molecular mechanism is still remaining elusive. Though different classical models, viz., dominance, overdominance and epistasis still holds true, the recent studies on epigenomics, transcriptomic, proteomic, metabolomics and circadian model have provided new insights. Multigene models have been proposed as the basis of complementation of allelic and gene expression variation, which is a major probable contributor to heterosis. The evolving epigenetic and genomic field put forward the role of interaction of alleles from different parental genomes in reprogramming the genes involved in stress tolerance, fitness and growth of hybrids. In the majority of the studies, transcriptomic, proteomic and metabolomic studies have found many complex regulatory network changes in genetic, epigenetic, regulatory and biochemical levels and only a few patterns could be established. Thus, heterosis is the outcome of the series of interactions in the genomes. Furthermore, epigenetic modifications of the circadian clock genes and their reciprocal regulators were reported to regulate the expression of downstream genes and pathways leading to more product accumulation in hybrids. Moreover, the majority of the epigenetic studies are limited to Arabidopsis thaliana and Zea mays, however, such studies on different crops may further bring more insights on the role of epigenetic mechanisms in determining heterosis. Further, none of the models is capable to explain heterosis alone which reflects the limitations of the individual model. The present review critically assesses different theories from different fields and also unravels the existing rapid methods to exploit them.

摘要

杂种优势已在植物和动物中得到广泛利用，并且通过改善重要的农艺性状也彻底改变了农业。然而，分子机制仍然难以捉摸。虽然不同的经典模型，即.、支配、过度支配和上位性仍然成立，最近对表观基因组学、转录组学、蛋白质组学、代谢组学和昼夜节律模型的研究提供了新的见解。已提出多基因模型作为等位基因和基因表达变异互补的基础，这是杂种优势的主要可能因素。不断发展的表观遗传和基因组领域提出了来自不同亲本基因组的等位基因的相互作用在重编程参与胁迫耐受性、适应性和杂种生长的基因中的作用。在大多数研究中，转录组学、蛋白质组学和代谢组学研究在遗传、表观遗传、调控和生化水平上发现了许多复杂的调控网络变化，但只能建立少数模式。因此，杂种优势是基因组中一系列相互作用的结果。此外，据报道，生物钟基因及其相互调节因子的表观遗传修饰可调节下游基因和途径的表达，从而导致杂种中更多的产物积累。此外，大多数表观遗传研究仅限于然而，拟南芥和玉米对不同作物的研究可能会进一步深入了解表观遗传机制在决定杂种优势中的作用。此外，没有一个模型能够单独解释杂种优势，这反映了单个模型的局限性。本综述批判性地评估了来自不同领域的不同理论，并揭示了利用它们的现有快速方法。