The KNOX (KNOTTED1-like homeobox) transcription factors play an important role in leaf, shoot apical meristem and seed development and respond to biotic and abiotic stresses. In this study, we analyzed the diversity and evolutionary history of the KNOX gene family in the genome of tetraploid cotton (Gossypium hirsutum). Forty-four putative KNOX genes were identified. All KNOX genes from seven higher plant species were classified into KNOXI, KNOXII, and KNATM clades based on a phylogenetic analysis. Chromosomal localization and collinearity analysis suggested that whole-genome duplication and a polyploidization event contributed to the expansion of the cotton KNOX gene family. Analyses of expression profiles revealed that the GhKNOX genes likely responded to diverse stresses and were involved in cotton growth developmental processes. Silencing of GhKNOX2 enhanced the salt tolerance of cotton seedlings, whereas silencing of GhKNOX10 and GhKNOX14 reduced seedling tolerance to salt stress. Silencing of GhSTM3 influenced the cotton flowering time and plant development. These findings clarify the evolution of the cotton KNOX gene family and provide a foundation for future functional studies of KNOX proteins in cotton growth and development and response to abiotic stresses.
Node of first fruiting/sympodial branch (NFFB) and its height (HNFFB) are two important indicators to measure cotton (Gossypium spp.) early maturity. This study performed an association mapping using the mixed linear model (MLM) procedure for NFFB and HNFFB based on 172 Upland cotton (Gossypium hirsutum L.) cultivars and 331 polymorphic SSR markers. The gene diversity index of 331 markers ranged from 0.0387 to 0.7799 with a mean value of 0.4002 and the polymorphism information content ranged from 0.0379 to 0.7473 with a mean value of 0.3375. A total of 18 markers associated with NFFB were detected in at least two environments, and the range of explained phenotypic variation by markers in different environments was 2.28-11.36 % with a mean value of 5.20 %. A total of 19 markers associated with HNFFB were detected in at least two environments, and the range of explained phenotypic variation by markers in different environments was 2.83-16.96 % with a mean value of 7.92 %. These markers detected in multiple environments are of good stability and can be used for marker-assisted selection (MAS) of target traits. In addition, favorable alleles for NFFB and HNFFB were mined. These favorable alleles and their representative cultivars are expected to be used for breeding practices. This study provides theoretical basis for the further analysis of genetic basis of NFFB and HNFFB, as well as the use of MAS for cotton early maturity.Keywords Upland cotton (Gossypium hirsutum L.) Á Node of first fruiting/sympodial branch Á Height of node of first fruiting/sympodial branch Á Association mapping Á Favorable allele Abbreviations NFFB Node of first fruiting/sympodial branch HNFFB Height of node of first fruiting/sympodial branch SSR Simple sequence repeat QTL Quantitative trait locus/loci LD Linkage disequilibrium MLM Mixed linear model MAS Marker-assisted selection Electronic supplementary material The online version of this article (
The AP1/FUL transcription factors are important for floral development, but the underlying molecular mechanisms remain unclear. In this study, we cloned and identified two AP1/FUL-like genes, GhAP1.1 and GhFUL2, in upland cotton, which is a commonly cultivated economically valuable crop. Sequence alignments and phylogenetic analyses indicated GhAP1.1 and GhFUL2, which are encoded by genes in the AP1/FUL clade, have conserved N-terminals, but diverse C-terminal domains. A quantitative real-time PCR analysis revealed that GhAP1.1 and GhFUL2 were expressed in the flower and root, and had the opposite expression patterns during different shoot apical meristem stages. The upregulated expression of GhAP1.1 in Arabidopsis and the silencing of GhAP1.1 did not induce significant changes to the flowering time or floral organs, but the transcript levels of the florigen FT gene and the AP1 homolog GhMADS42 increased. The overexpression of GhFUL2 in Arabidopsis delayed flowering and promoted bolting by decreasing the FT and LFY expression levels. Silencing GhFUL2 in cotton dramatically increased the expression of GhFT and GhMADS42 and promoted flowering. Additionally, yeast two-hybrid and bimolecular fluorescence complementation assays indicated that GhAP1.1 can interact with the SVP homolog GhSVP2.2, whereas GhFUL2 can form heterodimers with GhSEP3/GhSEP4 homologs, and GhSVP2.2. Therefore, we proved that the functional divergence of GhAP1.1 and GhFUL2, which involved changes in sequences and expression patterns, influenced the regulation of cotton flower development and plant architecture.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.