Knockdown of the atypical protein kinase genes GhABC1K2-A05 and GhABC1K12-A07 make cotton more sensitive to salt and PEG stress

Activity of bc1 complex kinase(ABC1K)is an atypical protein kinase(aPK)that plays a crucial role in plant mitochondrial and plastid stress responses,but little is known about the responses of ABC1Ks to stress in cotton(Gossypium spp.).Here,we identified 40 ABC1Ks in upland cotton(Gossypium hirsutum L.)and found that the Gh ABC1Ks were unevenly distributed across 17 chromosomes.The GhABC1K family members included 35 paralogous gene pairs and were expanded by segmental duplication.The GhABC1K promoter sequences contained diverse cis-acting regulatory elements relevant to hormone or stress responses.The qRT-PCR results revealed that most Gh ABC1Ks were upregulated by exposure to different stresses.Gh ABC1K2-A05 and Gh ABC1K12-A07 expression levels were upregulated by at least three stress treatments.These genes were further functionally characterized by virus-induced gene silencing(VIGS).Compared with the controls,the Gh ABC1K2-A05-and Gh ABC1K12-A07-silenced cotton lines exhibited higher malondialdehyde(MDA)contents,lower catalase(CAT),peroxidase(POD)and superoxide dismutase(SOD)activities and reduced chlorophyll and soluble sugar contents under NaCl and PEG stress.In addition,the expression levels of six stress marker genes(Gh DREB2A,Gh SOS1,Gh CIPK6,Gh SOS2,Gh WRKY33,and Gh RD29A)were significantly downregulated after stress in the Gh ABC1K2-A05-and Gh ABC1K12-A07-silenced lines.The results indicate that knockdown of Gh ABC1K2-A05 and Gh ABC1K12-A07 make cotton more sensitive to salt and PEG stress.These findings can provide valuable information for intensive studies of Gh ABC1Ks in the responses and resistance of cotton to abiotic stresses.

GhAP1-D3 positively regulates flowering time and early maturity with no yield and fiber quality penalties in upland cotton

Flowering time(FTi)is a major factor determining how quickly cotton plants reach maturity.Early maturity greatly affects lint yield and fiber quality and is crucial for mechanical harvesting of cotton in northwestern China.Yet,few quantitative trait loci(QTLs)or genes regulating early maturity have been reported in cotton,and the underlying regulatory mechanisms are largely unknown.In this study,we characterized 152,68,and 101 loci that were significantly associated with the three key early maturity traits—FTi,flower and boll period(FBP)and whole growth period(WGP),respectively,via four genome-wide association study methods in upland cotton(Gossypium hirsutum).We focused on one major early maturity-related genomic region containing three single nucleotide polymorphisms on chromosome D03,and determined that GhAP1-D3,a gene homologous to Arabidopsis thaliana APETALA1(AP1),is the causal locus in this region.Transgenic plants overexpressing GhAP1-D3 showed significantly early flowering and early maturity without penalties for yield and fiber quality compared to wild-type(WT)plants.By contrast,the mutant lines of GhAP1-D3 generated by genome editing displayed markedly later flowering than the WT.GhAP1-D3 interacted with GhSOC1(SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1),a pivotal regulator of FTi,both in vitro and in vivo.Changes in GhAP1-D3 transcript levels clearly affected the expression of multiple key flowering regulatory genes.Additionally,DNA hypomethylation and high levels of H3K9ac affected strong expression of GhAP1-D3 in early-maturing cotton cultivars.We propose that epigenetic modifications modulate GhAP1-D3 expression to positively regulate FTi in cotton through interaction of the encoded GhAP1 with GhSOC1 and affecting the transcription of multiple flowering-related genes.These findings may also lay a foundation for breeding early-maturing cotton varieties in the future.

基于历史性城市景观与数字足迹视角的遗产廊道选线方法——以中国南京市历史城区为例

遗产廊道作为一种串联历史文化与自然景观资源的系统性保护方法,融合了人文环境与自然环境,可以为公众提供休闲娱乐、游憩健身等活动的连续线性空间。传统的遗产廊道选线研究大多聚焦于分析物质空间条件,忽略了公众感知表达和公共参与机制。基于历史性城市景观理念挖掘与传统遗产内容紧密关联的现代景观资源,通过解析游憩者的数字足迹,将人群游憩行为偏好与空间感知纳入遗产廊道选线过程,可实现城市物理语义选线与社会语义选线的结合。基于此,本研究包括三个部分:1)通过数字足迹分析,将城市传统遗产与景观资源点纳入遗产廊道选线过程,通过最小累积阻力模型拟合物理语义选线结果;2)利用数字足迹中的人群流动轨迹与网络文本信息构建共词矩阵,完成社会语义选线;3)耦合物理语义选线与社会语义选线结果,结合实际情况优化遗产廊道选线结果。研究实现了在遗产廊道选线过程中,将城市景观资源与公众游憩行为和空间感知的有效整合,有利于城市遗产的整体保护与公共空间的系统提升。