染色质可及性在基因转录调控中起着至关重要作用。然而，染色质可及性的调控机制，及其调控玉米关键基因表达和籽粒发育的机制尚不清楚。本研究中，我们分离了一个玉米籽粒突变体，将其命名为dek219，该突变体表现为粉质胚乳和胚停止发育。Dek219编码DICER-LIKE1 (DCL1)蛋白，是一种miRNA生物发生的必需酶。Dek219功能缺失导致大多数miRNAs和组蛋白基因的表达水平显著降低。进一步研究表明，热激转录因子Hsf17-Zm00001d016571模块可能是影响组蛋白基因表达的因素之一。转座酶可及染色质测序分析(ATAC-seq)表明，与野生型(WT)相比，dek219的染色质可及性发生了改变，这可能调控了籽粒发育中关键基因的表达。通过分析WT和dek219之间的差异表达基因(DEGs)和差异可及染色质区域(ACRs)，我们鉴定到119个受染色质可及性调控的候选基因，包括已报道的玉米籽粒发育关键基因。综上所述，这些结果表明Dek219影响染色质可及性和关键基因的表达，是玉米籽粒发育所必需的。

Invasion of the oriental fruit fly, Bactrocera dorsalis, into new niches containing different food sources (a process referred to as host shift), may cause population genetic differentiation and sympatric speciation. To attempt to infer that experimentally, test populations were established by transferring a subset of the original populations, which had been grown on banana for many generations, onto navel orange, and then subculturing the navel orange population and banana population for at least 20 generations. Four pairs of SSR primers with high polymorphism on laboratory strains were used to detect population genetic differentiation. All six tested populations (the 5th, 10th and 15th generations of B. dorsalis fed on banana and navel orange, respectively) were found to have low genetic diversity. Furthermore, the genetic diversity of the navel orange populations was found to decline after being crossed for several generations. Populations initially were deviated from Hardy-Weinberg equilibrium, however, equilibrium was achieved with increasing numbers of generations in both of the host populations. Limited gene flows were found among the six populations. The Nei’s standard genetic distances between the two host populations of the same generation were initially low, but increased with generation number. Genetic distances between banana and navel orange populations of the same generation were lower than genetic distances between different generations grown on the same host plant. Analysis of molecular distance (AMOVA) results based on generation groups and host groups demonstrated that genetic variation among generations was greater than that between the two host populations. The results indicated that population genetic differentiation occurred after the host shift, albeit at low level. Biogeography and taxonomy of the B. dorsalis complex revealed that speciation of B. dorsalis might be tightly associated with host shift or host specialization of B. dorsalis following dispersal.