The MADS-Box Transcription Factor EjAGL65 Controls Loquat Flesh Lignification via Direct Transcriptional Inhibition of EjMYB8

Genome-wide identification and analysis of MIKC-type MADS-box genes expression in Chimonanthus salicifolius

BACKGROUND

MIKC type MADS-box transcription factors are one of the largest gene families and play a pivotal role in flowering time and flower development. Chimonanthus salicifolius belongs to the family Calycanthaceae and has a unique flowering time and flowering morphology compared to other Chimonanthus species, but the research on MIKC type MADS-box gene family of C. salicifolius has not been reported.

OBJECTIVE

Identification, comprehensive bioinformatic analysis, the expression pattern of MIKC-type MADS-box gene family from different tissues of C. salicifolius.

METHODS

Genome-wide investigation and expression pattern under different tissues of the MIKC-type MADS-box gene family in C. salicifolius, and their phylogenetic relationships, evolutionary characteristics, gene structure, motif distribution, promoter cis-acting element were performed.

RESULTS

A total of 29 MIKC-type MADS-box genes were identified from the whole genome sequencing. Interspecies synteny analysis revealed more significant collinearity between C. salicifolius and the magnoliids species compared to eudicots and monocots. MIKC-type MADS-box genes from the same subfamily share similar distribution patterns, gene structure, and expression patterns. Compared with Arabidopsis thaliana, Nymphaea colorata, and Chimonanthus praecox, the FLC genes were absent in C. salicifolius, while the AGL6 subfamily was expanded in C. salicifolius. The selectively expanded promoter (AGL6) and lack of repressor (FLC) genes may explain the earlier flowering in C. salicifolius. The loss of the AP3 homologous gene in C. salicifolius is probably the primary cause of the morphological distinction between C. salicifolius and C. praecox. The csAGL6a gene is specifically expressed in the flowering process and indicates the potential function of promoting flowering.

CONCLUSION

This study offers a genome-wide identification and expression profiling of the MIKC-types MADS-box genes in the C. salicifolius, and establishes the foundation for screening flowering development genes and understanding the potential function of the MIKC-types MADS-box genes in the C. salicifolius.

The MADS-box gene EjAGL15 positively regulates lignin deposition in the flesh of loquat fruit during its storage

Introduction

Lignification of fruit flesh is a common physiological disorder that occurs during post-harvest storage, resulting in the deterioration of fruit quality. Lignin deposition in loquat fruit flesh occurs due to chilling injury or senescence, at temperatures around 0°C or 20°C, respectively. Despite extensive research on the molecular mechanisms underlying chilling-induced lignification, the key genes responsible for the lignification process during senescence in loquat fruit remain unknown. MADS-box genes, an evolutionarily conserved transcription factor family, have been suggested to play a role in regulating senescence. However, it is still unclear whether MADS-box genes can regulate the lignin deposition that arises from fruit senescence.

Methods

Both senescence- and chilling-induced flesh lignification were simulated by applying temperature treatments on loquat fruits. The flesh lignin content during the storage was measured. Transcriptomic, quantitative reverse transcription PCR and correlation analysis were employed to identify key MADS-box genes that may be involved in flesh lignification. The Dual-luciferase assay was utilized to identify the potential interactions between MADS-box members and genes in phenylpropanoid pathway.

Results and Discussion

The lignin content of the flesh samples treated at 20°C or 0°C increased during storage, but at different rates. Results from transcriptome analysis, quantitative reverse transcription PCR, and correlation analysis led us to identify a senescence-specific MADS-box gene, EjAGL15, which correlated positively with the variation in lignin content of loquat fruit. Luciferase assay results confirmed that EjAGL15 activated multiple lignin biosynthesis-related genes. Our findings suggest that EjAGL15 functions as a positive regulator of senescence-induced flesh lignification in loquat fruit.

MaC2H2-like regulates chilling stress response of ‘Fenjiao’ banana by modulating flavonoid synthesis and fatty acid desaturation

Chilling injury (CI) is a major problem that affects fruit quality and ripening. Herein, chilling stress severely inhibited the expression of transcription factor MaC2H2-like. MaC2H2-like activates the expression of genes associated with flavonoid synthesis (MaC4H-like1, Ma4CL-like1, MaFLS, and MaFLS3) and fatty acid desaturation (MaFAD6-2 and MaFAD6-3), the leading indicators of chilling tolerance. MaC2H2-like interacts with MaEBF1 and boosts the transcriptional activity of MaFAD6-2, MaFAD6-3, Ma4CL-like1, and MaFLS. The overexpression of MaC2H2-like reduced fruit CI, induced the expression of these genes and increased the content of flavonoid and unsaturated fatty acid. Meanwhile, the silencing of MaC2H2-like increased fruit CI and downregulated the expression of those genes and reduced the content of flavonoid and unsaturated fatty acid. These results indicate that MaC2H2-like function as new player in modulating fruit CI by regulating flavonoid synthesis and fatty acid desaturation. MaC2H2-like could be a useful candidate gene for improving cold tolerance in 'Fenjiao' banana.

The Regulatory Mechanisms and Control Technologies of Chilling Injury and Fungal Diseases of Postharvest Loquat Fruit

Loquat is a popular fruit widely cultivated all over the world. It is rich in minerals and carotenoids and has high commercial value. At room temperature, loquat fruit is impressionable to water and nutritional losses, physical damage, and microbial decay, resulting in a short postharvest life. Low-temperature storage is routinely used to prolong the shelf life of loquat fruit; however, cold storage can also lead to lignification of flesh tissue, which is one of the major symptoms of chilling injury (CI), reducing the quality and economic value of the fruit. In addition, fruit decay caused by microbial infection is another important reason for postharvest losses of loquat. To reduce quality deterioration and optimize the postharvest storage strategies of loquat fruit, considerable progress has been made in the physiological and molecular biological studies of CI, microbial decay, and preservation technologies of loquat fruit during the postharvest phase in recent decades. This review summarizes the current research progress and provides a reference for the improvement of loquat fruit quality.