Integrating Genome-wide association and whole transcriptome analysis to reveal genetic control of leaf traits in Gossypium arboreum L

Leaves are important organs for crop photosynthesis and transpiration, and their morphological characteristics can directly reflect the growth state of plants. Accurate measurement of leaf traits and mining molecular markers are of great significance to the study of cotton growth. Here, we performed a Genome-wide association study on 7 leaf traits in 213 Asian cotton accessions. 32 significant SNPs and 44 genes were identified. A field experiment showed significant difference in leaf hair and leaf area between DPL971 and its natural mutant DPL972. We also compared the leaf transcriptome difference between DPL971 and DPL972, and found a batch of differentially expressed genes and non-coding RNAs (including lncRNAs, microRNAs, and circRNAs). After integrating the GWAS and transcriptome results, we finally selected two coding genes (Ga03G2383 and Ga05G3412) and two microRNAs (hbr-miR156, unconservative_Chr03_contig343_2364) as the candidate for leaf traits. Those findings will provide important genomic resources for cotton leaf improvement breeding.

Genome-wide association study for seedling biomass-related traits in Gossypium arboreum L

BACKGROUND

Seedling stage plant biomass is usually used as an auxiliary trait to study plant growth and development or stress adversities. However, few molecular markers and candidate genes of seedling biomass-related traits were found in cotton.

RESULT

Here, we collected 215 Gossypium arboreum accessions, and investigated 11 seedling biomass-related traits including the fresh weight, dry weight, water content, and root shoot ratio. A genome-wide association study (GWAS) utilizing 142,5003 high-quality SNPs identified 83 significant associations and 69 putative candidate genes. Furthermore, the transcriptome profile of the candidate genes emphasized higher expression of Ga03G1298, Ga09G2054, Ga10G1342, Ga11G0096, and Ga11G2490 in four representative cotton accessions. The relative expression levels of those five genes were further verified by qRT-PCR.

CONCLUSIONS

The significant SNPs, candidate genes identified in this study are expected to lay a foundation for studying the molecular mechanism for early biomass development and related traits in Asian cotton.

Genetic Factors Underlying Single Fiber Quality in A-Genome Donor Asian Cotton (Gossypium arboreum)

The study of A-genome Asian cotton as a potential fiber donor in Gossypium species may offer an enhanced understanding of complex genetics and novel players related to fiber quality traits. Assessment of individual fibers providing classified fiber quality information to the textile industry is Advanced Fiber Information System (AFIS) in the recent technological era. Keeping the scenario, a diverse collection of 215 Asiatic cotton accessions were evaluated across three agro-ecological zones of China. Genome-Wide Association Studies (GWAS) was performed to detect association signals related to 17 AFIS fiber quality traits grouped into four categories viz: NEPs, fiber length, maturity, and fineness. Significant correlations were found within as well as among different categories of various traits related to fiber quality. Fiber fineness has shown a strong correlation to all other categories, whereas these categories are shown interrelationships via fiber-fineness. A total of 7,429 SNPs were found in association with 17 investigated traits, of which 177 were selected as lead SNPs. In the vicinity of these lead SNPs, 56 differentially expressed genes in various tissues/development stages were identified as candidate genes. This compendium connecting trait-SNP-genes may allow further prioritization of genes in GWAS loci to enable mechanistic studies. These identified quantitative trait nucleotides (QTNs) may prove helpful in fiber quality improvement in Asian cotton through marker-assisted breeding as well as in reviving eroded genetic factors of G. hirsutum via introgression breeding.

Comparative proteomic analyses of Asian cotton ovules with attached fibers in the early stages of fiber elongation process

BACKGROUND

Plenty of proteomic studies were performed to characterize the allotetraploid upland cotton fiber elongation process, whereas little is known about the elongating diploid cotton fiber proteome.

METHODS

In this study, we used a two-dimensional electrophoresis-based comparative proteomic approach to profile dynamic proteomes of diploid Asian cotton ovules with attached fibers in the early stages of fiber elongation process. One-way ANOVA and Student-Newman-Keuls test were used to find the differentially displayed protein (DDP) spots.

RESULTS

A total of 55 protein spots were found having different abundance ranging from 1 to 9 days post-anthesis (DPA) in a two-day interval. These 55 DDP spots were all successfully identified using high-resolution mass spectrometric analyses. Gene ontology analyses revealed that proteoforms involved in energy/carbohydrate metabolism, redox homeostasis, and protein metabolism are the most abundant. In addition, orthologues of the 13 DDP spots were also found in differential proteome of allotetraploid elongating cotton fibers, suggesting their possible essential roles in fiber elongation process.

CONCLUSIONS

Our results not only revealed the dynamic proteome change of diploid Asian cotton fiber and ovule during early stages of fiber elongation process but also provided valuable resource for future studies on the molecular mechanism how the polyploidization improves the trait of fiber length.