Гетерозис: современные тенденции в изучении молекулярных механизмов

Гетерозис как феномен превосходства гибридов F1 над родителями служит основным механизмом повышения продуктивности в сельскохозяйственном производстве, но при этом остается одним из наиболее интригующих явлений с точки зрения генетики. Первые попытки выяснения его генетических основ базировались на использовании теоретических моделей, которые, хотя и были приняты научным сообществом, но не могли в полной мере охарактеризовать это уникальное явление. С разработкой и распространением молекулярных маркеров основные усилия были направлены на поиск геномных регионов, ответственных за формирование гетеротического ответа в F1, и выяснение перспектив использования оценки молекулярной дивергенции исходных родительских форм для предсказания урожайного потенциала гибридного потомства. Несмотря на некоторые успехи, эффективность такого подхода для практического использования оказалась ограниченной. Выполненные исследования подтвердили, что генетическая гетерогенность необходима, но не достаточна для получения гетерозисного фенотипа. Развитие современных методологических подходов функциональной геномики и смежных дисциплин обеспечило новые возможности для изучения основополагающих механизмов гетерозиса на уровне генома, транскриптома, метаболома и эпигенома в связи с различными типами взаимодействия генов (доминированием, сверхдоминированием, эпистазом). К настоящему времени описаны различия в геномной организации, генной экспрессии и эпигенетическом статусе гибридов F1 и их родителей. На геномном уровне обнаружены QTL, ассоциированные с гетерозисом, изучена роль дивергенции ДНК в реализации генетического потенциала F1. На уровне транскриптома у гибридов, по сравнению с инбредными родителями, выявлены изменения в регуляции экспрессии генов, осуществляемой с участием генов циркадных часов. Опре-делена важная роль эпигенетической модификации ДНК и геномного импринтинга в проявлении гетерозиса. Вся совокупность данных, накопленных к настоящему времени, свидетельствует о том, что гетерозис невозможно объяснить единственным общим механизмом, так как этот сложный феномен включает множественные компоненты, кумулятивный эффект которых приводит к формированию выдающегося фенотипа.

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