Chrysanthemum (Chrysanthemum morifolium) CmHRE2-like negatively regulates the resistance of chrysanthemum to the aphid (Macrosiphoniella sanborni).

BACKGROUND: The growth and ornamental value of chrysanthemums are frequently hindered by aphid attacks. The ethylene-responsive factor (ERF) gene family is pivotal in responding to biotic stress, including insect stress. However, to date, little is known regarding the involvement of ERF transcription factors (TFs) in the response of chrysanthemum to aphids. RESULTS: In the present study, CmHRE2-like from chrysanthemum (Chrysanthemum morifolium), a transcription activator that localizes mainly to the nucleus, was cloned. Expression is induced by aphid infestation. Overexpression of CmHRE2-like in chrysanthemum mediated its susceptibility to aphids, whereas CmHRE2-like-SRDX dominant repressor transgenic plants enhanced the resistance of chrysanthemum to aphids, suggesting that CmHRE2-like contributes to the susceptibility of chrysanthemum to aphids. The flavonoids in CmHRE2-like-overexpression plants were decreased by 29% and 28% in two different lines, whereas they were increased by 42% and 29% in CmHRE2-like-SRDX dominant repressor transgenic plants. The expression of Chrysanthemum-chalcone-synthase gene(CmCHS), chalcone isomerase gene (CmCHI), and flavonoid 3'-hydroxylase gene(CmF3'H) was downregulated in CmHRE2-like overexpression plants and upregulated in CmHRE2-like-SRDX dominant repressor transgenic plants, suggesting that CmHRE2-like regulates the resistance of chrysanthemum to aphids partially through the regulation of flavonoid biosynthesis. CONCLUSION: CmHRE2-like was a key gene regulating the vulnerability of chrysanthemum to aphids. This study offers fresh perspectives on the molecular mechanisms of chrysanthemum-aphid interactions and may bear practical significance for developing new strategies to manage aphid infestation in chrysanthemums.

The Small Auxin-Up RNA SAUR10 Is Involved in the Promotion of Seedling Growth in Rice.

Small auxin-up-regulated RNAs (SAURs) are genes rapidly activated in response to auxin hormones, significantly affecting plant growth and development. However, there is limited information available about the specific functions of SAURs in rice due to the presence of extensive redundant genes. In this study, we found that OsSAUR10 contains a conserved downstream element in its 3' untranslated region that causes its transcripts to be unstable, ultimately leading to the immediate degradation of the mRNA in rice. In our investigation, we discovered that OsSAUR10 is located in the plasma membrane, and its expression is regulated in a tissue-specific, developmental, and hormone-dependent manner. Additionally, we created ossaur10 mutants using the CRISPR/Cas9 method, which resulted in various developmental defects such as dwarfism, narrow internodes, reduced tillers, and lower yield. Moreover, histological observation comparing wild-type and two ossaur10 mutants revealed that OsSAUR10 was responsible for cell elongation. However, overexpression of OsSAUR10 resulted in similar phenotypes to the wild-type. Our research also indicated that OsSAUR10 plays a role in regulating the expression of two groups of genes involved in auxin biosynthesis (OsYUCCAs) and auxin polar transport (OsPINs) in rice. Thus, our findings suggest that OsSAUR10 acts as a positive plant growth regulator by contributing to auxin biosynthesis and polar transport.

Identification and co-expression network analysis of plumule-preferentially expressed genes in Oryza sativa.

BACKGROUND: The seedling establishment is controlled by the programmed expression of sets of genes at the specific tissues of seed, abundance and environment. Plumule is an important part of the seed embryo and expresses the suits of genes to exert distinct functions during seed germination. Although rice genomic resources are available and developed rapidly, thousands of transcripts have not previously been located in the plumule of rice. OBJECTIVE: This study was performed to identify plumule-preferentially expressed (OsPluP) genes in rice and determine the expression profiles and functions of OsPluP genes. METHODS: We identified the OsPluP genes through Affymetrix microarray data. Meanwhile, qRT-PCR was performed to validate the expression pattern, also found that OsPluP genes were regulated by dark/light treatment. The cis-acting regulatory elements were analyzed in the promoters' regions of OsPluP genes. The T-DNA mutant of the OsPluP seed was used to reveal the function in seed germination. RESULTS: In this study, a genomic survey of OsPluP genes was performed, and we identified 88 OsPluP genes based on Affymetrix microarray data. The expression profiles of 88 OsPluP members in 24 representative tissues covering rice whole life cycle can be roughly classified into three major groups, suggesting functional divergence of OsPluP genes in seed germination. The microarray data, qRT-PCR, and promoter analysis results demonstrated that transcripts of more than half OsPluPs (54 genes) could be enhanced in the darkness and respond to phytohormone. Gene Ontology (GO)and Kyoto encyclopedia of genes and genomes (KEGG) analysis demonstrated that OsPluP and their co-expressed genes were highly enriched in fatty acid metabolism. Moreover, OsPluP82 T-DNA mutant seeds displayed short plumule length and storage lipid accumulation. CONCLUSION: This study would enable the functions of OsPluP genes during seed germination and contribute to the goal of molecular regulatory networks that lay the foundation for further studies of seedling growth.

PIN and PILS family genes analyses in Chrysanthemum seticuspe reveal their potential functions in flower bud development and drought stress.

Auxin affects almost all plant growth and developmental processes. The PIN-FORMED (PIN) and PIN-LIKES (PILS) family genes determine the direction and distribution gradient of auxin flow by polar localization on the cell membrane. However, there are no systematic studies on PIN and PILS family genes in chrysanthemum. Here, 18 PIN and 13 PILS genes were identified in Chrysanthemum seticuspe. The evolutionary relationships, physicochemical properties, conserved motifs, cis-acting elements, chromosome localization, collinearity, and expression characteristics of these genes were analyzed. CsPIN10a, CsPIN10b, and CsPIN10c are unique PIN genes in C. seticuspe. Expression pattern analysis showed that these genes had different tissue specificities, and the expression levels of CsPIN8, CsPINS1, CsPILS6, and CsPILS10 were linearly related to the developmental period of the flower buds. In situ hybridization assay showed that CsPIN1a, CsPIN1b, and CsPILS8 were expressed in floret primordia and petal tips, and CsPIN1a was specifically expressed in the middle of the bract primordia, which might regulate lateral expansion of the bracts. CsPIN and CsPILS family genes are also involved in drought stress responses. This study provides theoretical support for the cultivation of new varieties with attractive flower forms and high drought tolerance.

Characterization of the TCP Gene Family in Chrysanthemum nankingense and the Role of CnTCP4 in Cold Tolerance.

Plant-specific TCP transcription factors play a key role in plant development and stress responses. Chrysanthemum nankingense shows higher cold tolerance than its ornamental polyploid counterpart. However, whether the TCP gene family plays a role in conferring cold tolerance upon C. nankingense remains unknown. Here, we identified 23 CnTCP genes in C. nankingense, systematically analyzed their phylogenetic relationships and synteny with TCPs from other species, and evaluated their expression profiles at low temperature. Phylogenetic analysis of the protein sequences suggested that CnTCP proteins fall into two classes and three clades, with a typical bHLH domain. However, differences between C. nankingense and Arabidopsis in predicted protein structure and binding sites suggested a unique function of CnTCPs in C. nankingense. Furthermore, expression profiles showed that expression of most CnTCPs were downregulated under cold conditions, suggesting their importance in plant responses to cold stress. Notably, expression of miR319 and of its predicted target genes, CnTCP2/4/14, led to fast responses to cold. Overexpression of Arabidopsis CnTCP4 led to hypersensitivity to cold, suggesting that CnTCP4 might play a negative role in C. nankingense responses to cold stress. Our results provide a foundation for future functional genomic studies on this gene family in chrysanthemum.

Characterization of the Rosa roxburghii Tratt transcriptome and analysis of MYB genes.

Rosa roxburghii Tratt (Rosaceae) has a fruit that is flavorful, economically valuable, and highly nutritious, providing numerous health benefits. Myeloblastosis (MYB) proteins play key roles in the development and fruit quality of R. roxburghii. However, there is little available genomic and transcriptomic information for R. roxburghii. Here, a normalized cDNA library was constructed from five tissues, including the stem, leaf, flower, young fruit, and mature fruit, using the Illumina HiSeq 3000 platform. De novo assembly was performed, and 470.66 million clean reads were obtained. In total, 63,727 unigenes, with an average GC content of 42.08%, were discovered, 60,406 of which were annotated. In addition, 9,354 unigenes were assigned to Gene Ontology categories, and 20,202 unigenes were assigned to 25 Eukaryotic Ortholog Groups. Additionally, 19,508 unigenes were classified into 140 pathways of the Kyoto Encyclopedia of Genes and Genomes database. Based on the transcriptome, 163 unigenes associated with MYBs were detected. Among these genes, 75 genes were significantly expressed in the various tissues, including 10 R1 MYB, 42 R2R3 MYB, one R1R2R3 MYB, three R4 MYB and 19 atypical MYB-like proteins. The expression levels of the 12 MYB genes randomly selected for quantitative real-time PCR analysis corroborated the RNA sequencing results. A total of 37,545 microsatellites were detected, with an average expressed sequence tag-simple sequence repeat frequency of 0.59 (37,545/63,727). This transcriptome data improves our understanding of the role of MYB in R. roxburghii and will be valuable for identifying genes of interest.

GLABROUS1 from Rosa roxburghii Tratt regulates trichome formation by interacting with the GL3/EGL3 protein.

GLABROUS1 is an R2R3 MYB homolog that is essential for the initiation of trichome development. In this study, we used RACE to clone a full-length cDNA from Rosa roxburghii Tratt, termed RrGL1, which was 1013 bp, including an open reading frame of 792 bp that encoded 263 amino acids. In situ hybridization, corresponding with qRT-PCR results, revealed that RrGL1 transcripts were mainly expressed in petiole, leaf, and stem. RrGL1 expression levels at various fruit developmental stages in R. roxburghii were also evaluated. RrGL1 was highly expressed in young fruit, and the expression level decreased with fruit maturation. The overexpression of RrGL1 was able to functionally complemented the Arabidopsis thaliana gl1-/- mutant in trichome formation. RrGL1 was located in the cell nucleus with analysis of subcellular localization and physically interacted with A. thaliana GL3/EGL3 in the yeast two-hybrid assay, implying that RrGL1 might exert functions by forming a MYB-basic helix-loop-helix complex in trichome initiation. The formation of prickles in R. roxburghii is similar to that of Arabidopsis trichome. These results provided a foundation for further research on the molecular mechanisms underlying the formation and development of prickles that could assist and cultivate in the genetic engineering of prickle-free fruits.