Abstract
Heterosis refers to the increase in biomass, stature, fertility, and other characters that impart superior performance to the F1 progeny over genetically diverged parents. The manifestation of heterosis brought an economic revolution to the agricultural production and seed sector in the last few decades. Initially, the idea was exploited in cross-pollinated plants, but eventually acquired serious attention in self-pollinated crops as well. Regardless of harvesting the benefits of heterosis, a century-long discussion is continued to understand the underlying basis of this phenomenon. The massive increase in knowledge of various fields of science such as genetics, epigenetics, genomics, proteomics, and metabolomics persistently provide new insights to understand the reasons for the expression of hybrid vigor. In this review, we have gathered information ranging from classical genetic studies, field experiments to various high-throughput omics and computational modelling studies in order to understand the underlying basis of heterosis. The modern-day science has worked significantly to pull off our understanding of heterosis yet leaving open questions that requires further research and experimentation. Answering these questions would possibly equip today’s plant breeders with efficient tools and accurate choices to breed crops for a sustainable future.
Highlights
Heterosis, alternatively known as ‘outbreeding enhancement’, is characterized by the increase in vigor, biomass, speed of development and fertility relative to the average ofThe genetically diverged two parents [1]
Heterosis is frequently encountered in allogamous plants that are prone to inbreeding depression, rather than autogamous plants that prefer selfing [6]
According to East, the extent of the heterotic effect is proportional to the genetic distance between the two parental lines, but this relationship ceases at an optimum level and declines beyond that point due to either reproductive barriers or lack of adaptation of the parents
Summary
Alternatively known as ‘outbreeding enhancement’, is characterized by the increase in vigor, biomass, speed of development and fertility relative to the average of. Heterosis in plant breeding is often described with different terms andextended definitions Alternative terminologies such as ‘Heterobeltiosis’ and ‘Commercial Heterosis’ are used to indicate superior performance of a hybrid compared to either better-performing parents or a control cultivar, respectively. The occurrence of heterosis can be discerned as a ‘system-wide’ phenomenon that results in enhanced size, vigor, resistance to pest/disease, or climatic factors influencing crop performance on a crop and is taken as an overall ‘effect’ This standpoint of heterosis has made plant breeders benefit from this phenomenon to breed better crops but has given rise to the search for a unifying theory and investigations on various scientific levels to understand the underpinnings of hybrid vigor. The three most important models are Dominance, Over-dominance and Pseudo-overdominance model (Figure 2). 4Inofa1d8dition, Epistasis has been under discussion as an underlying reason for crop heterosis (Figure 2, IV)
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