研究發(fā)現(xiàn)，雜種不僅繼承了雙親的遺傳和表觀遺傳特征，獲得了更豐富的基因資源和更多的染色質(zhì)可及性區(qū)域，還能利用優(yōu)勢(shì)等位基因應(yīng)對(duì)鹽脅迫。這表明，表觀遺傳通過調(diào)控基因表達(dá)增強(qiáng)了雜種基因組的可塑性，賦予其更強(qiáng)的環(huán)境適應(yīng)性。同時(shí)，研究從耐鹽性狀層面支持了雜種優(yōu)勢(shì)的經(jīng)典假說：在油菜雜交種“華油雜62”中，遺傳效應(yīng)以不完全顯性和加性效應(yīng)為主，而顯性和超顯性效應(yīng)相對(duì)較少，說明雜種在單個(gè)基因位點(diǎn)上的表現(xiàn)通常高于低值親本，但未超過高值親本。然而，不同親本的優(yōu)勢(shì)等位基因通過互補(bǔ)和累積，使總體作用超過了加性效應(yīng)，從而賦予了雜種在鹽脅迫下的優(yōu)勢(shì)。上述研究表明，育種者可通過篩選優(yōu)良耐鹽親本、優(yōu)化雙親雜交組合，聚合功能位點(diǎn)、實(shí)現(xiàn)優(yōu)勢(shì)互補(bǔ)，從而培育出強(qiáng)耐鹽堿油菜新品種，為耐鹽堿油菜育種提供理論指導(dǎo)。

 

　　據(jù)悉，團(tuán)隊(duì)專注耐鹽堿油菜研究20年，育成“華油雜62”、“飼油2號(hào)”、“華油雜158”、“金油雜9號(hào)”等一系列代表性耐鹽堿雜交品種。該研究回答了“雜交油菜為何更耐鹽堿”的基本科學(xué)問題，為未來耐鹽堿油菜遺傳育種提供了重要參考。

 

　　華中農(nóng)業(yè)大學(xué)博士研究生陳俊霖和張敏燕為該論文的共同第一作者，沈金雄教授和趙倫教授為共同通訊作者。華中農(nóng)業(yè)大學(xué)趙虎研究員、江漢大學(xué)萬何平博士等給予了重要指導(dǎo)。該研究得到了國(guó)家自然科學(xué)基金、國(guó)家重點(diǎn)研發(fā)計(jì)劃等項(xiàng)目資助。

 

　　論文鏈接： http://doi.org/10.1111/nph.70532

 

　　英文摘要：

 

　　Heterosis holds great potential for improving yield, quality, and environmental adaptability in crop breeding, which suggests that hybrids can exhibit better performance in adapting to extreme environments. However, the epigenetic mechanisms of salt-tolerant heterosis in allopolyploid crop Brassica napus (AACC, 2n = 38), particularly chromatin accessibility, remain largely unexplored.

 

　　We investigated the dynamics of chromatin accessibility and transcriptional reprogramming during a time course of salt exposure in Brassica napus hybridization. We observed the importance of epigenetic and transcriptional regulation in plant resilience. The chromatin accessibility and transcriptome rapidly changed within a short time frame of salt exposure.

 

　　Hybrid possessed more accessible chromatin and more active transcriptome than that of parents driven by epigenetic aggregation and genetic complementation. Broader and more flexible genomic resources enabled hybrid preferentially unitized advantageous alleles for salt stress adaptation. Meanwhile, these salt stress-responsive genes in hybrid exerted various heterotic effects, with non-additive genetic effects, including full-dominance, partial-dominance, and overdominance effects, playing a crucial role in salt stress adaptation.

 

　　Our results expanded the heterosis hypothesis from an epigenetic perspective and emphasized how the combined effects of genetic and epigenetic factors enable hybrid to better withstand salt stress.