上海科技大学知识管理系统

Postzygotic reproductive isolation, which results in the irreversible divergence

of species, is commonly accompanied by hybrid sterility, necrosis/weakness, or

lethality in the F1 or other offspring generations. Here we show that the loss of

function of HWS1 and HWS2, a couple of duplicated paralogs, together confer

complete interspecific incompatibility between Asian and African rice. Both of

these non-Mendelian determinants encode the putative Esa1-associated factor 6

(EAF6) protein, which functions as a characteristic subunit of the histone H4

acetyltransferase complex regulating transcriptional activation via genome-wide

histone modification. The proliferating tapetum and inappropriate polar nuclei

arrangement cause defective pollen and seeds in F2 hybrid offspring due to the

recombinant HWS1/2-mediated misregulation of vitamin (biotin and thiamine)

metabolism and lipid synthesis. Evolutionary analysis of HWS1/2 suggests that

this gene pair has undergone incomplete lineage sorting (ILS) and multiple gene

duplication events during speciation. Our findings have not only uncovered a

pair of speciation genes that control hybrid breakdown but also illustrate a

passive mechanism that could be scaled up and used in the guidance and opti

mization of hybrid breeding applications for distant hybridization.