Xingying Yan

Soybean (Glycine max (L.) Merr.) was originally domesticated in China and is a kind of significant leguminous crop, which can fix atmospheric nitrogen to bioavailable nitrogen in association with rhizobia. Ceramides, intermediates of sphingolipids, are crucial structural components in membrane formation and also function as signaling molecules, which play crucial roles in plant development and defense. Although Arabidopsis ceramide synthase genes AtLOH1 and AtLOH3 overexpression plants increased biomass compared to the wild type, the potential mechanism in plant growth was still unclear. A soybean ceramide synthase gene 1 (GmCS1) has a high expression level in the stem, and the protein is localized in the endoplasmic reticulum. Overexpression of GmCS1 promotes soybean lateral branch development for effective branch formation, significantly increasing the number of lateral branches and pods. Using transcriptomic profiles, we found that GmCS1 overexpression lines displayed the upregulation of plant hormone signal transduction pathway gene expression in developmental branches. Actually, Indole-3-acetic acid (IAA) induces bud outgrowth rather than initiation according to the determination of endogenous IAA and cytokinin (CKs) in soybean lateral branches. Collectively, these results suggest that GmCS1 may be a functional ceramide synthase gene in soybean, with the GmCS1-mediated regulatory network playing a crucial role in controlling branch development by IAA and CKs homeostasis. Exploring the regulation mechanisms by GmCS1 overexpression lines is essential for Ideal Soybean Architecture (ISA) innovation.

Cotton is an important cash crop globally. Cotton fiber is the main economic product of cotton plants. Phosphorus, as one of the essential nutrients, plays an important role in plant growth and development. However, few studies focus on phosphorus regulating fiber elongation. In this study, we used the cotton ovule culture system in vitro to explore the effects of various phosphorus levels on fiber and ovule growth, and screened for phosphorus-responsive factor, as well as revealed its action mechanism. The results indicated that fiber elongation was more sensitive than ovule growth to phosphorus deficiency. GhPHR1, a homolog of phosphate starvation response 1 (PHR1) in upland cotton, was significantly upregulated in fibers and ovules under phosphorus-deficient conditions. GhPHR1 directly binds to the promoter of the glucosylceramide synthase gene in cotton (GhGCS1) and positively regulates its expression. Overexpressing GhGCS1 enhanced phosphorus uptake and transport in cotton, increased phosphorus content in fiber cells, and promoted fiber cell elongation. Conversely, downregulating GhGCS1 reduced phosphorus content in fiber cells and suppressed fiber elongation. These findings demonstrate the importance of the GhPHR1-GhGCS1 molecular module in regulating fiber cell elongation and elucidate the molecular mechanism by which phosphorus influences fiber elongation.

Background: Gossypium hirsutum L. is one of the main economic crops worldwide, and increasing the size/weight of its seeds is a potential strategy to improve its seed-related yield. AINTEGUMENTA (ANT) is an organogenesis transcription factor mediating cell proliferation and expansion in Arabidopsis, but little is known about its candidate function in upland cotton seed. Results: In this study, functional characterization of GhANT in the cotton seed development stage was performed. The expression pattern analysis showed that GhANT was predominantly expressed in the ovules, and its expression was consistent with the ovules’ development stage. Heterologous expression of GhANT in Arabidopsis promoted plant organ growth and led to larger seeds. Importantly, specific expression of GhANT by the TFM7 promoter in the cotton ovules enlarged the seeds and increased the cotton seed yield, as compared with the wild-type in a three-year field trial. Furthermore, transcription level analysis showed that numerous genes involved in cell division were up-regulated in the ovules of TFM7::GhANT lines in comparison to the wild-type. These results indicate that GhANT is a potential genetic resource for improving cotton seed yield through its molecular links with cell cycle controllers.

Boosting evidence indicated lipids play important roles in plants. To explore lipid function in cotton fiber development, the lipid composition and content were detected by untargeted and targeted lipidomics. Compared with rapid elongation fibers, the lipid intensity of 16 sub-classes and 56 molecular species decreased, while only 7 sub-classes and 26 molecular species increased in the fibers at the stage of secondary cell wall deposition. Unexpectedly, at the rapid elongation stage, 20 sub-classes and 60 molecular species increased significantly, while only 5 sub-classes and 8 molecular species decreased in the ligon lintless-1 (li-1) mutant compared with its wild-type Texas Maker-1 (TM-1). Particularly, campesteryl, sitosteryl, and total steryl ester increased by 21.8-, 48.7-, and 45.5-fold in the li-1 fibers, respectively. All the molecular species of sphingosine-1-P, phytoceramide-OHFA, and glucosylceramide increased while all sphingosine, phytosphingosine, and glycosyl inositol phospho ceramides decreased in the li-1 fibers. Similarly, the different expression genes between the mutant and wild type were enriched in many pathways involved in the lipid metabolism. Furthermore, the number of lipid droplets also increased in the li-1 leaf and fiber cells when compared with the wild type. These results illuminated that fiber cell elongation being blocked in the li-1 mutant was not due to a lack of lipids, but rather lipid over-accumulation (obesity), which may result from the disruption of sphingolipid and sterol metabolism. This study provides a new perspective for further studying the regulatory mechanisms of fiber development.

Cotton is the most important natural fiber crop in the world. Cotton fiber cells are not only the major economic product of cotton, but also an ideal material for studying the growth and development of plant cell. The fiber cell elongation and secondary cell wall development of short and thick fiber mutant ligon lintless-1 (li-1) are severely impaired. However, its mechanism is still unclear. Boosting evidence showed that sphingolipids and sterols play important roles in the growth and development of fiber cell. But it is unknown that the changes of these lipids are in the li-1 fiber cells. In the study, we detected the lipid profiles of 10-DPA and 20-DPA fiber cells of wild type (TM-1), and 10-DPA fiber cells of li-1 mutant by untargeted and targeted lipidomics. In the result, seven lipid classes, 33 lipid sub-classes, and 793 lipid molecular species were detected by untargeted lipidomics. Nine sphingolipid species and seven sterols were detected by targeted lipidomics. The PA, PC, PE, PI, CER, CerG1, DG, TG, and AGlcSiE enriched in fiber cells. 23 lipid sub-classes and 82 lipid molecular species were altered significantly between 10-DPA and 20-DPA fiber cells. Compared with 10-DPA fibers, the lipid intensity of 16 sub-classes and 56 lipid molecular species decreased while 7 lipid sub-classes and 26 lipid molecular species increased in the fibers at stage of SCW deposition (20-DPA). Similarly, obvious difference was detected between li-1 and TM-1 fibers. Compared with TM-1, 20 lipid sub-classes and 60 lipid molecular species increased significantly, only five lipid sub-classes and eight lipid molecular species decreased in li-1 mutant. It is surprising that the sitosterol ester increased by 59.56 fold in li-1 fibers. Detailed sphingolipid and sterol profiles indicated all molecular species of S1P, PhytoCer-OHFA, and GluCer increased while all molecular species of Sph, PhytoSph, and GIPC decreased in li-1 fibers. The mutant fiber cells showed a significantly increase in campesteryl ester, sitosteryl ester, and total steryl ester, with 21.8, 48.7, and 45.5 fold increases, respectively. Moreover, transcriptome analysis indicated that the different expression genes between TM-1 and li-1 fibers enriched in the pathway of fatty acid elongation and degradation, glycosphingolipid biosynthesis, glycerophospholipid metabolism, and brassinosteroid biosynthesis. Furthermore, the number of oil body also increased in li-1 leaf and fiber cell when compared with wild type. These results illuminated that fiber cell elongation was blocked in the li-1 mutant was not due to a lack of lipids, but rather lipid over-accumulation (obesity), which may result from the disruption of sphingolipid and sterol metabolism. This study provides a new perspective for further studying the regulatory mechanisms of fiber development.

Rapeseed is an important commercial crop globally, used for both animal fodder and human consumption. Varied insolation duration and intensity are among the main factors affecting the seed yield and quality of Brassica napus (B. napus) worldwide. In this study, the high-oil-content rapeseed cultivar “Qingyou 3” was subjected to a light supplementation trial during both the vegetative growth period and the seed productive stage. Different light intensity conditions were stimulated using light-emitting diodes (LEDs). The main plot factor was land condition, with LED treatment (Treatment) and without LED treatment (Control) under natural conditions. The results showed that the leaf size and thickness, photosynthesis efficiency, and seed oil content of B. napus increased significantly after light supplementation. Then, 18 cDNA libraries were constructed from leaf segments (30 days after transplanting—DAT) and seeds 30 and 40 days after pollination (DPA) for RNA transcriptome sequencing. It was found that genes encoding lipid transfer protein, phenylpropanoid biosynthesis, photosynthesis, and plant hormone signal transduction were enriched in differentially expressed genes (DEGs). The qRT-PCR analysis showed that eight key genes had significant variations, a finding also consistent with the RNA-seq results. The aim of this study was to identify the DEGs and signaling pathways in the leaves and seeds of B. napus during the vegetative and seed productive stages under different light intensities. The results provide insight into how sufficient light plays a critical role in promoting photosynthesis and serves as the foundation for material accumulation and yield formation.

Rapeseed is an important commercial crop in the world, which is used for animal fodder and human consumption. The varied insolation duration and intensity is one of the main reasons for effecting the seed yield and seed quality of Brassica napus (B. napus) in worldwide. In this study, a highly oil seed content rapeseed cultivar “Qingyou 3” was subjected to light supplementary trial at both vegetative growth period and the seed productive stage. Different light quantity conditions were stimulated by light-emitting diodes (LED), main plot factor was land condition under LED (Treatment) and without LED (Control) in natural condition. The size and thickness of leaves, photosynthesis efficiency, seed oil content of B. napus increased significantly after light supplementary. Eighteen cDNA libraries were constructed from leaf segments (30 days after transplanting, 30 DAT) and seed 30 and 40 days after pollination (DPA) for RNA transcriptome sequencing. It was found that genes encoding lipid transfer protein, phenylpropanoid biosynthesis and plant hormone signal transduction were enriched in differentially expressed genes. This study is aim to identify the differentially expressed genes and signaling pathways in the leaves and seed of B. napus at the vegetative and seed productive stages under different light quantity. All the results provide the knowledge for understanding sufficient light plays a critical role in promoting photosynthesis, and is the basis of material accumulation and yield formation.

Verticillium wilt, caused by Verticillium dahliae, is a devastating disease for many important crops, including cotton. Kiwellins (KWLs), a group of cysteine-rich proteins synthesized in many plants, have been shown to be involved in response to various phytopathogens. To evaluate genes for their function in resistance to Verticillium wilt, we investigated KWL homologs in cotton. Thirty-five KWL genes (GhKWLs) were identified from the genome of upland cotton (Gossypium hirsutum). Among them, GhKWL1 was shown to be localized in nucleus and cytosol, and its gene expression is induced by the infection of V. dahliae. We revealed that GhKWL1 was a positive regulator of GhERF105. Silencing of GhKWL1 resulted in a decrease, whereas overexpression led to an increase in resistance of transgenic plants to Verticillium wilt. Interestingly, through binding to GhKWL1, the pathogenic effector protein VdISC1 produced by V. dahliae could impair the defense response mediated by GhKWL1. Therefore, our study suggests there is a GhKWL1-mediated defense response in cotton, which can be hijacked by V. dahliae through the interaction of VdISC1 with GhKWL1.