Sorghum bicolor (L.) is one of the oldest crops cultivated by human beings which has been used in food and wine making. To understand the genetic diversity of sorghum breeding resources and further guide molecular-marker-assisted breeding, six yield-related traits were analyzed for 214 sorghum germplasm from all over the world, and 2,811,016 single-nucleotide polymorphisms (SNPs) markers were produced by resequencing these germplasms. After controlling Q and K, QTLs were found to be related to the traits using three algorisms. Interestingly, an important QTL was found which may affect multiple traits in this study. It was the most likely candidate gene for the gene SORBI_3008G116500, which was a homolog of Arabidopsis thaliana gene-VIP5 found by analyzing the annotation of the gene in the LD block. The haplotype analysis showed that the SORBI_3008G116500^hap3 was the elite haplotype, and it only existed in Chinese germplasms. The traits were proven to be more associated with the SNPs of the SORBI_3008G116500 promoter through gene association studies. Overall, the QTLs and the genes identified in this study would benefit molecular-assisted yield breeding in sorghum.

In sorghum [Sorghum bicolor (L.) Moench], combining ability and heterosis analysis are commonly used to evaluate superior parental lines and to screen for strongly heterotic hybrids, which helps in sorghum variety selection and breeding. In this context, combining ability and heterosis analysis were assessed using 14 restorer lines and seven cytoplasmic male sterile (CMS) lines in 2019 and 2020. The analysis of variance of all cross combinations had highly significant differences for all characters studied, which indicated a wide variation across the parents, lines, testers, and crosses. Combining ability analysis showed that the general combining ability (GCA) and specific combining ability (SCA) of the different parents were differed significantly among different traits. Most combinations with high SCA also showed high GCA in their parent lines. The heritability in the narrow sense of grain weight per panicle and grain yield was relatively low, indicating that the ability of these traits to be directly inherited by offspring was weak, that they were greatly affected by the environment. The better-parent heterosis for plant height, grain weight per panicle, panicle length, and 1000-grain weight was consistent with the order of mid-parent heterosis from strong to weak. The GCA effects of two lines 10480A, 3765A and three testers 0-30R, R111, and JY15R were significant for the majority of the agronomic traits including grain yield and might be used for improving the yield of grains in sorghum as parents of excellent specific combining ability. Seven strongly heterotic F₁ hybrids were screened; of these, hybrids 3765A × R111, 1102A × L2R, and 3765A × JY15R showed significant increases in seed iristectorigenin A content and will feature into the creation of new sorghum varieties rich in iristectorigenin A.

The artificial allotetraploid of Gossypium herbaceun and G. raimondii was created in the laboratory to broaden the genetic background of cotton and provide novel materials for the germplasm innovation of cotton. In this study, fiber characters, physiological and biochemical comparison, SSR markers and floral transcriptomes analysis were conducted among three generations of the artificial allotetraploid and their parents, including G. hirsutum L. acc. TM-1. The results showed that the fiber color of artificial allotetraploid, light yellow, mid-parent of G. herbaceun and G. raimondii, and the fiber length was close to TM-1. The activities of SOD, POD, CAT, and MDA content in artificial allotetraploid plants were significantly higher than parents and TM-1, indicating that the stress resistance of artificial allotetraploid was enhanced after distant hybridization and chromosome doubling. 55 polymorphic loci were detected from 11 pairs of SSR primers, with 2-10 mutation loci per primer and an average of 5. PIC ranged from 0.498 to 0.892, with an average of 0.742. The results indicated that SSR markers could reflect rich genetic diversity information among the test materials. The complementary of parents and specific bands were amplified in S2, S3, and S4, simultaneously, indicating that chromosome segment recombination occurred in the artificial allotetraploid at the molecular level. There were 37, 19, and 20 bands of S2, S3, and S4 identical with TM-1 respectively, among which 17 bands were shared with TM-1 by all generations, indicating that the artificial allotetraploid had homology in genetic background with TM-1. The floral organ transcriptome analysis showed that there were 5653 differentially expressed genes (DEGs) between artificial allotetraploid and TM-1, in which 3062 were up-regulated and 2591 were down-regulated. GO functional analysis showed that DEGs had significant differences in photosynthesis, photosystem II, RNA directed DNA polymerase activity and other pathways. KEGG enrichment analysis showed that DEGs were more active in photosynthetic-antenna proteins, photosynthesis and isoflavone biosynthesis. The enrichment analysis of fertility related DEGs between artificial allotetraploids and TM-1 revealed that most of the DEGs of artificial allotetraploids in pollen development and recognition were down-regulated, which may be the key factor leading to low seed setting percentage of artificial allotetraploid. Three G-type lectin receptor serine/threonine protein kinases (Gh_D01G067500, Gh_D05G168100, Gh_A01G062500) were obtained from Nr annotation information by clustering. The results showed that the artificial allotetraploid performed advantage in fiber color, resistance to stress and photosynthesis, combining the excellent quality of its parents. It is expected to restore its fertility by crossbreeding with G. hirsutum, and to further cultivate a valuable novel material for production.

Background: Information on the autopolyploid of Gossypium herbaceum remains limited until now. Previously, the autotetraploid of G. herbaceum was successfully generated via colchicine-induced chromosome doubling from the diploid cultivar ‘Hongxing’ in our lab. Methods: To investigate the drought stress response mechanism of this tetraploid, the autotetraploid S4 was used as the experimental material. The plants were subjected to drought stress during the flowering stage, followed by measurements of physiological and biochemical indicators and transcriptomic sequencing analysis. Results: Under drought stress, MDA content increased, and cell membranes sustained oxidative damage. Photosynthetic parameters, such as net photosynthetic rate (Pn), were significantly suppressed, while the activity of osmotic regulators and key antioxidant enzymes increased significantly. After rehydration, all of the above physiological indicators showed varying degrees of recovery. Transcriptome analysis revealed that, when comparing the treatment group with the control group, a total of 5530 differentially expressed genes (DEGs) were identified, with 2714 up-regulated and 2816 down-regulated. Furthermore, this study investigated the drought resistance mechanism involving the interaction between the MAPK signaling pathway and other metabolic pathways in the autotetraploid. Nine drought-resistant genes, including MAPK3, bHLH47, GaRbohD, RIBA1, PIP1-3, RCA1, RbohD, CYP707A and HSP70, were selected and analyzed using real-time quantitative PCR; the results were generally consistent with the transcriptomic data. Conclusions: These findings substantially enhance our understanding of the molecular mechanisms underlying drought responses in autotetraploids. This novel autotetraploid genotype expands the available cotton germplasm resources and is expected to hold significant value for research on polyploidy evolution.

Background Heterosis has been widely used for breeding high-yield crops, changes crop breeding and agricultural production by increasing yield. Transcriptome profiles of sorghum spikes in hybrid Jinnuo 3 and its parents 10480A and L17R were performed by RNA sequencing technology at secondary branch and spikelet differentiation period. Results During above two differentiation period, there were 2,641 and 2,175 differentially expressed genes (DEGs) between Jinnuo 3 and 10480A, respectively. Meanwhile, there were 1,387 and 1,094 DEGs between Jinnuo 3 and L17R, respectively. These indicated that massive DEGs were existed between hybird and its parents, and a more similar expression pattern was presented between hybrid and male parent. Gene expression inheritance analysis showed that most of genes were expressed additively, suggesting that the complementary effect may play a foundation role in sorghum spike heterosis. Among non-additive expression genes, L17R-dominant genes were predominant, indicating that male parent may provide beneficial alleles with great contribution to heterosis. GO and KEGG analysis suggested that metabolic pathways, such as photosynthetic antenna protein, photosynthesis, carbon fixation in photosynthetic organisms, amino acid metabolism, glycolysis, and endoplasmic reticulum protein processing, would participate in yield heterosis formation in hybrid Jinnuo 3. Further analysis showed that photosynthesis-related genes PsbW, PsbR, Lhca2, Lhcb1 and LAX3, spike structure development-related genes MADS1, MADS7, MADS16 and MADS55, as well as stress resistance-related genes WRKY14, WRKY35, HSFB2C and HSP70, might play an important role in yield heterosis formation in hybrid Jinnuo 3. Conclusion Hybrids Jinnuo 3 increased yield by simultaneously increasing source (photosynthetic efficiency-related genes), library (spike development-related genes), and resistance (inresistance-related genes). This molecular mechanism could provide new clues for sorghum heterosis utilization and high-yield breeding.