Genome-Wide Identification, Characterization, and Expression Profile Analysis of CONSTANS-like Genes in Woodland Strawberry (Fragaria vesca)

CONSTANS-like 13 homologs MiCOL13 A and MiCOL13B orchestrate flowering time and salt-drought tolerance in mango

The CO/COL gene family serves as a central regulator of photoperiod-dependent floral transition and exhibits functional diversification in plant adaptation to abiotic stress conditions. Through comprehensive analysis of the genomic data from the mango cultivar Guire 82 (Mangifera indica L.), two COL13 homologs, designated MiCOL13 A and MiCOL13B, were successfully characterized. Phylogenetic categorization revealed that MiCOL13 A and MiCOL13B cluster within evolutionary clade III of the CONSTANS-like superfamily. These two homologous genes displayed a circadian rhythm and were strongly expressed in the leaves throughout the flowering induction phase. Under short-day (SD) conditions, the flowering time of Arabidopsis strains overexpressing MiCOL13 A and MiCOL13B was significantly delayed. However, overexpression of MiCOL13 A promoted early flowering in Arabidopsis, and MiCOL13B delayed flowering under long-day (LD) conditions. Subcellular localization demonstrated that the nucleus was the location of MiCOL13 A and MiCOL13B. The study also revealed that the overexpression of MiCOL13 A and MiCOL13B enhances Arabidopsis resistance to salt and drought stresses, resulting in overexpressing lines with longer roots and higher survival rates. Investigations of physiological and biochemical parameters revealed that elevated expression of MiCOL13 A/B significantly upregulated the expression of stress-responsive endogenous genes in A. thaliana under saline and drought conditions. Moreover, yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) analyses revealed that the MiCOL13A and MiCOL13B proteins interact with two stress-related proteins, zinc finger protein 4 (MiZFP4) and MYB30-INTERACTING E3 LIGASE 1 (MiMIEL1). Together, our findings indicate that MiCOL13 A and MiCOL13B have dual functions in controlling flowering and responding to abiotic stress in plants.

Genome-wide characterization and expression analysis of the CONSTANS-like gene family of Juglans mandshurica Maxim

The zinc-finger proteins encoded by the CONSTANS-like (COLs) gene family in Juglans mandshurica Maxim. play a significant role in regulating photoperiod-dependent flowering time, as well as in various processes such as growth and development. In this study, 15 members of the CONSTANS-like gene family were identified based on the genomic data of Juglans mandshurica. All of these proteins possess an N-terminal zinc-finger B-box domain and a C-terminal CCT domain. Phylogenetic analysis indicates that the JmCOLs proteins can be divided into three subgroups, with gene structures and motif compositions varying among these subgroups. Chromosomal analysis reveals that the 15 JmCOLs genes are distributed across nine chromosomes. The promoters of genes in this family contain stress-related cis-acting elements, hormone-related response elements, and other elements associated with growth and development. Notably, the most prominent elements are the light-responsive elements, suggesting that genes in this family are predominantly expressed in leaves. The expression patterns of JmCOLs genes differ among the members. Specifically, JmCOL5 and JmCOL10 are expressed exclusively in flower buds (p < 0.05). Throughout the 10 stages of flower bud development, the overall expression level of JmCOL4a peaks at approximately 50 to 100 times higher than its lowest point. The expression pattern of JmCOL5, which first reaches its maximum during the physiological differentiation stage of protogynous male flower buds before declining, suggests its potential involvement in the development of heteromorphic and dichogamous flowers.

Genome-wide identification and functional analysis of the longan CONSTANS (CO) family

Longans are among the most economically important subtropical fruits. Its flowering is sensitive to the photoperiod, and flowering time has a significant influence on yield and quality. CONSTANS-like (COL) gene plays a key role in regulating induced flowering in longans. However, the specific role of the COL gene family in the regulation of flowering remains unknown. In this study, 10 DlCOL genes were identified in longans using comprehensive bioinformatics analysis and named based on their physical chromosomal locations. Phylogenetic tree analysis showed that DlCOL genes were divided into three subfamilies, each with a conserved domain. When combined with collinearity analysis, we found DlCOL genes were more closely related to COL genes of dicotyledons. DlCOL family genes are differentially expressed in various longan organs, with DlCOL1, DlCOL3, and DlCOL9 expressed in all organs, with the highest expression levels in floral buds. In the differential expression at different flowering induction stages of 'Sijimi' ('SJ') or 'Shixia' longan ('SX'), DlCOL4 expression was upregulated by 3-fold at the "T1-T2" flowering induction stage in 'SJ', but there was no expression during the three flowering induction stages in 'SX'. Subcellular localization analysis indicated that DlCOL4 is localized in the nucleus. Heterologous transformation of Arabidopsis indicated that DlCOL4 can negatively regulate flowering in transgenic plants. The qRT-PCR (Quantitative real-time PCR) results related to flowering genes indicated that DICOL4 may inhibit flowering by interacting with AtTFL and AtCOL. This study demonstrates the potential functional role of the DlCOL gene and the key role of DlCOL4 in regulating longan flowering.

Function diversification of CONSTANS-like genes in Pyrus and regulatory mechanisms in response to different light quality

Pear (Pyrus L.) is a significant commercial fruit globally, with diverse species exhibiting variations in their flowering periods due to environmental factors. CONSTANS-like (COL) genes, known from previous studies in Arabidopsis, are key regulators of flowering time by sensing photoperiod. However, the evolutionary history and functions of COL genes in different pear species remain unclear. In this study, we identified a total of 79 COL genes in different pear species, including 12 COL genes in Pyrus bretschneideri 'DangshanSuli', 9 in Pyrus ussuriensis × hybrid 'Zhongai 1', 11 in Pyrus communis 'Bartlett', 13 in Pyrus betulifolia, 18 in Pyrus pyrifolia 'Cuiguan', 16 in Pyrus pyrifolia 'Nijisseiki'. Analysis of gene structure, phylogenetic tree, and multiple sequences provided valuable insights into the fundamental understanding of COL genes in pear. The impact of selection pressure on the PbrCOLs in Chinese white pear was assessed using Ka/Ks, revealing that the evolution rate of PbrCOLs was influenced by purification selection factors. The study also revealed different tissue-specific expression patterns of PbrCOLs under varying light quality. Real-time quantitative PCR revealed that under natural light conditions, the expression patterns of PbrCOL2, PbrCOL3, and PbrCOL4 are similar to previous studies on CONSTANS gene in Arabidopsis, with increased expression levels during the day and decreased levels at night. However, PbrCOL1, PbrCOL6, and PbrCOL9 exhibit different expression patterns, with decreased expression levels both during the day and at night. After red light treatment, high expression of PbrCOL3 and PbrCOL4 was observed at night, while the expression patterns of the other four genes did not show significant changes. Following blue light treatment, the expression peaks of PbrCOL1 and PbrCOL6 occurred during the night, showing opposite expression patterns compared to the study in Arabidopsis. The overexpression of PbrCOL3 significantly increase the chlorophyll content in pear seedlings, and its expression significantly affected the expression of other key flowering-related genes. Also, overexpression of PbrCOL3 resulted in a late-flowering phenotype in Arabidopsis. These findings indicate diverse responsive mechanisms and functions of PbrCOL genes on flowering time in pear. In conclusion, this study established a foundation for a deeper understanding of the specific roles of PbrCOLs in regulating the reproductive development of pear, particularly in the context of the photoperiodic flowering process.

Evaluation of reference genes and expression patterns of CONSTANS-LIKE genes in Tetrastigma hemsleyanum under different photoperiods

CONSTANS-LIKE (COL ) genes are a key signalling molecule that regulates plant growth and development during the photoperiod. Our preliminary experiments showed that the photoperiod greatly influence the formation of Tetrastigma hemsleyanum root tubers. In this study, we examined the oscillation patterns and expression characteristics of COL genes in leaves of T. hemsleyanum under different photoperiod conditions. Six genes were selected as candidate reference genes for further analyses: (1) 18S ribosomal RNA (18S rRNA ); (2) α-tubulin (TUBA ); (3) 30S ribosomal RNA (30S rRNA ); (4) TATA binding protein (TBP ); (5) elongation factor 1α (EF-1α ); and (6) RNA polymerase II (RPII ). The geNorm, NormFinder, and BestKeeper software programs were used to evaluate expression stability. Two ThCOL genes were screened in the T. hemsleyanum transcriptome library, and their expression patterns under different photoperiod conditions were analysed using quantitative reverse transcription PCR. The genes EF-1α , TUBA , and 18S rRNA were used to analyse the expression profiles of CONSTANS genes (ThCOL4 and ThCOL5 ) under different photoperiods. The expression peaks of ThCOL4 and ThCOL5 appeared at different times, demonstrating that their oscillation patterns were influenced by the photoperiod. We speculate that these two ThCOL genes may be involved in different biological processes.

CONSTANS, a HUB for all seasons: How photoperiod pervades plant physiology regulatory circuits

How does a plant detect the changing seasons and make important developmental decisions accordingly? How do they incorporate daylength information into their routine physiological processes? Photoperiodism, or the capacity to measure the daylength, is a crucial aspect of plant development that helps plants determine the best time of the year to make vital decisions, such as flowering. The protein CONSTANS (CO) constitutes the central regulator of this sensing mechanism, not only activating florigen production in the leaves but also participating in many physiological aspects in which seasonality is important. Recent discoveries place CO in the center of a gene network that can determine the length of the day and confer seasonal input to aspects of plant development and physiology as important as senescence, seed size, or circadian rhythms. In this review, we discuss the importance of CO protein structure, function, and evolutionary mechanisms that embryophytes have developed to incorporate annual information into their physiology.

COL2-dependent photoperiodic floral induction in Nicotiana sylvestris seems to be lost in the N. sylvestris × N. tomentosiformis hybrid N. tabacum

Introduction

Plants are sessile organisms that maximize reproductive success by adapting to their environment. One of the key steps in the reproductive phase of angiosperms is flower development, requiring the perception of multiple endogenous and exogenous signals integrated via a complex regulatory network. Key floral regulators, including the main transcription factor of the photoperiodic pathway (CONSTANS, CO) and the central floral pathway integrator (FLOWERING LOCUS T, FT), are known in many species.

Methods and results

We identified several CO-like (COL) proteins in tobacco (Nicotiana tabacum). The NtCOL2a/b proteins in the day-neutral plant N. tabacum were most closely related to Arabidopsis CO. We characterized the diurnal expression profiles of corresponding genes in leaves under short-day (SD) and long-day (LD) conditions and confirmed their expression in phloem companion cells. Furthermore, we analyzed the orthologs of NtCOL2a/b in the maternal LD ancestor (N. sylvestris) and paternal, facultative SD ancestor (N. tomentosiformis) of N. tabacum and found that they were expressed in the same diurnal manner. NtCOL2a/b overexpression or knock-out using the CRISPR/Cas9 system did not support a substantial role for the CO homologs in the control of floral transition in N. tabacum. However, NsCOL2 overexpression induced flowering in N. sylvestris under typically non-inductive SD conditions, correlating with the upregulation of the endogenous NsFTd gene.

Discussion

Our results suggest that NsFTd is transcriptionally regulated by NsCOL2 and that this COL2-dependent photoperiodic floral induction seems to be lost in N. tabacum, providing insight into the diverse genetics of photoperiod-dependent flowering in different Nicotiana species.

Genome-wide identification, expression analysis, and potential roles under low-temperature stress of bHLH gene family in Prunus sibirica

The basic helix-loop-helix (bHLH) family is one of the most well-known transcription factor families in plants, and it regulates growth, development, and abiotic stress responses. However, systematic analyses of the bHLH gene family in Prunus sibirica have not been reported to date. In this study, 104 PsbHLHs were identified and classified into 23 subfamilies that were unevenly distributed on eight chromosomes. Nineteen pairs of segmental replication genes and ten pairs of tandem replication genes were identified, and all duplicated gene pairs were under purifying selection. PsbHLHs of the same subfamily usually share similar motif compositions and exon-intron structures. PsbHLHs contain multiple stress-responsive elements. PsbHLHs exhibit functional diversity by interacting and coordinating with other members. Twenty PsbHLHs showed varying degrees of expression. Eleven genes up-regulated and nine genes down-regulated in -4°C. The majority of PsbHLHs were highly expressed in the roots and pistils. Transient transfection experiments demonstrated that transgenic plants with overexpressed PsbHLH42 have better cold tolerance. In conclusion, the results of this study have significant implications for future research on the involvement of bHLH genes in the development and stress responses of Prunus sibirica.

Genome-Wide Identification, Characterization and Expression Profiling of the CONSTANS-like Genes in Potato (Solanum tuberosum L.)

CONSTANS-like (COL) genes play important regulatory roles in flowering, tuber formation and the development of the potato (Solanum tuberosum L.). However, the COL gene family in S. tuberosum has not been systematically identified, restricting our knowledge of the function of these genes in S. tuberosum. In our study, we identified 14 COL genes, which were unequally distributed among eight chromosomes. These genes were classified into three groups based on differences in gene structure characteristics. The COL proteins of S. tuberosum and Solanum lycopersicum were closely related and showed high levels of similarity in a phylogenetic tree. Gene and protein structure analysis revealed similarities in the exon-intron structure and length, as well as the motif structure of COL proteins in the same subgroup. We identified 17 orthologous COL gene pairs between S. tuberosum and S. lycopersicum. Selection pressure analysis showed that the evolution rate of COL homologs is controlled by purification selection in Arabidopsis, S. tuberosum and S. lycopersicum. StCOL genes showed different tissue-specific expression patterns. StCOL5 and StCOL8 were highly expressed specifically in the leaves of plantlets. StCOL6, StCOL10 and StCOL14 were highly expressed in flowers. Tissue-specific expression characteristics suggest a functional differentiation of StCOL genes during evolution. Cis-element analysis revealed that the StCOL promoters contain several regulatory elements for hormone, light and stress signals. Our results provide a theoretical basis for the understanding of the in-depth mechanism of COL genes in regulating the flowering time and tuber development in S. tuberosum.