Abstract Rapid carotenoid accumulation during postharvest ripening determinants the visual appeal and nutritional quality of mango fruit. Abscisic acid (ABA) is a core phytohormone drives fleshy fruit ripening, yet the regulatory mechanism underlying ABA-enhanced carotenoid biosynthesis in postharvest mango ripening remains largely unclear. Our previous work identified MiPSY1 (phytoene synthase 1), a key structural gene for carotenoid biosynthesis, is transcriptionally activated by the bZIP transcription factor MibZIP66. Here, we show that endogenous ABA level is tightly correlated with carotenoid content during postharvest mango ripening. Exogenous ABA treatment markedly accelerates total carotenoids biosynthesis and upregulates the transcript abundance of both MiPSY1 and MibZIP66. Transient overexpression of MiPSY1 or MibZIP66 in mango fruit, and stable overexpression in transgenic tomato plants, both significantly boosts total carotenoid content. Yeast two-hybrid screening identified MiGF14k, a 14–3-3 family protein, interacting with MibZIP66 in the nucleus, and positively promotes carotenoid biosynthesis. MiGF14k and MibZIP66 synergistically regulated the transcription of MiPSY1 and this synergistic effect was further enhanced by ABA treatment. Furthermore, a phosphorylation-deficient mutation of conserved serine 316 in MibZIP66 eliminates the ABA-enhanced interaction between MibZIP66 and MiGF14k, and impairs the transactivation activity of the complex toward MiPSY1. Our findings uncover a MiGF14k–MibZIP66–MiPSY1 regulatory module that mediates ABA-enhanced carotenoid biosynthesis, in which phosphorylation of MibZIP66 serves as a molecular switch. This work elucidates a positive feedback regulation loop between the ABA signal and carotenoid biosynthesis during mango postharvest ripening, and supplies a molecular basis for breeding high-quality mango.

Browning of explants is a primary challenge on mango callus. However, some mango embryos remained un-browned upon inoculation. Bacterial plaques appeared around them after two days of culture. Isolation of endophytes from such embryos revealed that the dominant genera were Pantoea and Azospirillum. The bacterial plaques were cultured and centrifuged. The supernatant was filtered and added into the callus-induction medium. The browning area of mango embryos cultured on medium containing the filtered supernatant was about 5

Regulating floral induction (FI) through the application of gibberellin (GA) biosynthesis inhibitors is a critical agricultural practice to prevent yield loss in fruit trees. We observed that mepiquat chloride (MC), a highly safe plant growth retardant, enhanced FI in mango. Nevertheless, the molecular mechanism by which MC facilitates FI remains elusive. Using two distinct treatments and varied stages during FI in mango (Mangifera indica L. 'Tainong No.1'), 24 dynamic transcriptome profiles were constructed. Through pairwise comparisons and weighted gene co-expression network analysis (WGCNA), a regulatory network centered on the hub gene FLOWERING LOCUS T3 (MiFT3) was established. We further discovered MC-induced floral transition was associated with the decreases of GA20 and GA3 levels and the upregulation of MiGA2oxs (GA2 OXIDASES) expression, alongside the increase of abscisic acid (ABA) content and the upregulation of MiNCED1 (9-cis-epoxycarotenoid dioxygenase 1) and MiABI5-like7 (ABSCISIC ACID-INSENSITIVE 5-like7). Furthermore, biochemical assays and stable transgenic experiments were applied to confirmed that MiABI5-like7 activated the expression of MiFT3. Moreover, silencing MiABI5-like7 in mango buds delayed floral transition, while ectopic expression of MiABI5-like7 promoted early flowering. Additionally, exogenous ABA accelerated the floral transition induced by MC, whereas an ABA inhibitor delayed floral transition, which were associated with the expression levels of MiABI5-like7 and MiFT3. This study clarified the mechanism by which MC induced floral transition by inhibiting GA biosynthesis that activate MiABI5-like7-mediated signaling pathway, which provides novel insights into the regulatory network of FI in plants and offers a solution for solving the issue of insufficient flowering in warm winter climates.

The SWEET gene family is a group of genes with important functions in plants that is mainly involved in the transport and metabolism of carbohydrate substances. In this study, 32 mango (Mangifera indica L.) SWEET genes were screened and identified at the whole-genome level through bioinformatics methods. A systematic predictive analysis was conducted on their physicochemical properties, homology relationships, phylogenetic relationships, chromosomal locations, genomic structures, promoter cis-acting elements, and transcription factor regulatory networks. Meanwhile, the transcription levels of mango SWEET genes in different varieties and at different fruit development stages were also analyzed to obtain information about their functions. These results showed that 32 mango SWEET genes were unevenly distributed on 12 chromosomes. Phylogenetic analysis divided the SWEET proteins of mango, Arabidopsis thaliana (L.) Heynh., and Oryza sativa L. into four clades; in each clade, the mango SWEET proteins were more closely related to those of Arabidopsis. Four types of cis-acting elements were also found in the promoter regions of mango SWEET genes, including light-responsive elements, development-related elements, plant hormone-responsive elements, and stress-responsive elements. Interestingly, we found that the Misweet3 and Misweet10 genes showed strong expression in different mango varieties and at different fruit development stages, and they both belonged to the fourth Clade IV (G4) in the phylogenetic tree, indicating that they play a key role in the sugar accumulation process of mango. In this study, the upstream transcription factors of Misweet3, Misweet8, Misweet9, Misweet10, Misweet17, Misweet18, Misweet19, Misweet21, Misweet23, Misweet25, Misweet27, and Misweet31, those that had high expression levels in the transcriptome data, were predicted, and transcription factors such as ERF, NAC, WRKY, MYB, and C2H2 were screened. The results of this study provide a new way to further study the regulation of mango SWEET family genes on sugar accumulation, highlight their potential role in fruit quality improvement, and lay an important foundation for further study of mango SWEET function and enhance mango competitiveness in fruit market.

Seedless mangoes are desirable for fresh consumption and processing; however, they frequently exhibit poor fruit development and elevated abscission rates, necessitating applications of fruit regulators, though their physiological and molecular targets remain unclear. In this study, hormonal deficits and regulatory genes associated with mango fruit development were identified. Morphological observations showed that embryo-containing (EC) and embryo-absent (EA) fruits begin to diverge in development between 30 and 45 days after bloom (DAB). During this period, targeted metabolomics of gibberellins (GAs) detected nine GAs; four (GA20, GA34, GA4, GA7) behaved consistently across cultivars, with GA4 and GA7 showing the largest declines in EA fruit. Applying 50 mg/L GA3 or GA4+7 at 30 DAB increased fruit growth versus water, with GA4+7 having the greatest effect. Comparative transcriptomic analysis revealed 1476 shared DEGs that were enriched in hormone signaling pathways. Among 13 DEGs involved in GA biosynthesis, KAO (Mi05g23760.1) showed the strongest correlation with GA levels and was markedly downregulated in EA fruits. Together, these results indicate that deficiencies in GA4/GA7—potentially resulting from reduced KAO expression—contribute to impaired EA fruit development and that targeted GA4+7 supplementation may more effectively rescue growth than conventional GA3 treatments. These results provide mechanistic insights and practical guidance for hormone-based strategies to promote consistent development of seedless mangoes, thereby improving yield stability and supporting more sustainable production.

Sugar content critically determines mango fruit quality and varies significantly among varieties. Preliminary studies indicate that fructokinases (MiFRKs) MiFRK1 and MiFRK2 likely regulate intervarietal sugar variation. We characterized these MiFRKs using heterologous expression in tomato. Both isoforms phosphorylate fructose, promoting downstream catabolism, with R-MiFRK2 (from low-sugar ‘Renong No. 1’) exhibiting higher activity than T-MiFRK2 (high-sugar ‘Tainong No. 1’) and MiFRK1. Transcriptomic and metabolic analyses reveal that MiFRK overexpression inhibits sugar accumulation by altering the expression of key metabolic genes, including sucrose degradation enzymes (invertases), starch breakdown genes (β-amylases), and glycolytic genes (enolases). Intriguingly, MiFRK1 and MiFRK2 exhibit distinct regulatory effects on these pathways, suggesting functional specialization between the two isoforms. These findings provide novel insights into the molecular mechanisms through which MiFRKs govern sugar metabolism in mango, highlighting their potential as key targets for metabolic engineering to enhance fruit quality.

IntroductionMango is a vital horticultural fruit crop, and breeding is an essential strategy to enhance ongoing sustainability. Knowledge regarding population structure and genetic diversity in mango germplasm is essential for crop improvement.MethodsA set of 284 mango accessions from different regions of the world were subjected to high-throughput sequencing and specific-locus amplified fragment (SLAF) library construction to generate genomic single-nucleotide polymorphism (SNP).ResultsAfter filtering, raw data containing 539.61 M reads were obtained. A total of 505,300 SLAFs were detected, of which, 205,299 were polymorphic. Finally, 29,136 SNPs were employed to dissect the population structure, genetic relationships, and genetic diversity. The 284 mango accessions were divided into two major groups: one group consisted mainly of mango accessions from Australia, the United States, Cuba, India, Caribbean, Israel, Pakistan, Guinea, Burma, China, and Sri Lanka, which belonged to the Indian type (P1); the other group contained mango accessions from the Philippines, Thailand, Indonesia, Vietnam, Cambodia, Malaysia, and Singapore, which belonged to Southeast Asian type (P2). Genetic diversity, principal component analysis (PCA), and population structure analyses revealed distinct accession clusters. Current results indicated that the proposed hybridization occurred widely between P1 and P2.DiscussionMost of the accessions (80.99%) were of mixed ancestry, perhaps including multiple hybridization events and regional selection, which merits further investigation.

Background: The dramatic temperature fluctuations spurred by global warming and the accompanying extreme weather events inhibit mango growth and threaten mango productivity. Particularly, mango flowering is highly sensitive to temperature changes. The mango fruit setting rate was significantly positively correlated with pollen activity, and pollen activity was regulated by different metabolites. Methods: In this study, the in vitro pollen of two mango varieties (‘Renong No.1’ and ‘Jinhuang’), in which sensitivity to temperature differed significantly, were subjected to different temperature stresses (15 °C, 25 °C and 35 °C), and their metabolomics were analyzed. Results: The present results showed that 775 differential metabolites were screened by liquid chromatography–mass spectrometry and divided into 12 categories. The two varieties had significant differences in metabolite expression under different temperature stresses and the effect of low temperature on ‘Renong No.1’ mainly focused on amino acid metabolism, while the effect on ‘Jinhuang’ was mainly related to glycolysis. However, under the 35 °C temperature stress, ‘Renong No.1’ responded by redistributing riboflavin and betaine in vivo and the most obvious metabolic pathway of ‘Jinhuang’ enrichment was pyrimidine metabolism, which had undergone complex main body formation and extensive regulatory processes. The changes of metabolites of different varieties under low temperature and high temperature stress were different. Among them, flavonoids or flavonoid derivatives were included in class A (216 metabolites), C (163 metabolites) and D (233 metabolites) metabolites, indicating that flavonoid metabolites had an obvious regulatory effect on mango pollen metabolism under different temperature stress. Conclusions: The present results provide valuable information for reproductive biology studies and breeding in mango, in particular, the selection and breeding of the most suitable varieties for different production areas.

Because of their tolerance to root rot and many abiotic stresses, rootstocks are generally required for commercial avocado production. However, cutting and air-layering, which are popular methods of vegetative propagation for producing large numbers of uniform and genetically identical plants, have been unsuccessful for years. To develop a practical and efficient rooting procedure for selected avocado clonal rootstocks, the present research investigated the effects of various factors on rooting cutting. Shoots were divided into three groups (air layering, direct cutting, and stem-buried etiolation) and treated with different combinations (plant growth regulators, PGRs; soaking time; and culture media), in which orthogonal or randomized-block designs were used. The rooting rate, average root length, average root number, average root dry weight, and rooting quality (Q value) were used as evaluation indicators. The results show that etiolation treatment of the mother shoot is the requisite condition for avocado shoot rooting. In addition, the rooting effect of etiolated cuttings was strongly impacted by PGR type, concentration, and soaking time, whereas no significant differences were detected among the culture media. Among these factors, the roots and the survival rates of etiolated cuttings of two hard-to-root varieties were optimal under the following conditions: indolebutyric acid concentration of 2500 mg/L, dipping duration for 5 s, and perlite:vermiculite culture at 1:1. The rooting rate of ‘Dusa’ was generally greater than that of ‘Duke 7’ and reached 82%.

Mango (Mangifera indica L.) (2n = 40) is an important perennial fruit tree in tropical and subtropical regions. The lack of information on genetic diversity at the molecular level hinders efforts in mango genetic improvement and molecular marker-assisted breeding. In this study, a genome-wide screening was conducted to develop simple sequence repeat (SSR) markers using the Alphonso reference genome. A total of 187 SSR primer pairs were designed based on SSR loci with consisting of tri- to hexa-nucleotide motifs, and 34 highly polymorphic primer pairs were selected to analyze the diversity of 231 germplasm resources. These primers amplified 219 alleles (Na) across 231 accessions, averaging of 6.441 alleles for per marker. The polymorphic information content (PIC) values ranged from 0.509 to 0.757 with a mean of 0.620. Genetic diversity varied among populations, with Southeast Asia showing the highest diversity, and Australia the lowest. Population structure analysis, divided the accessions into two groups, Group I (India) and Group II (Southeast Asia), containing 104 and 127 accessions, respectively, consistent with results from phylogenetic analysis and principal component analysis (PCA). Sixteen SSR primer pairs capable of distinguishing all tested accessions, were selected as core primers for constructing fingerprints of 229 mango accessions. These findings offer valuable resources for enhancing the utilization of mango germplasm in breeding programs.

Spongy tissue in mango directly affects flesh quality and nutritional value, leading to enormous economic losses. In the current study, a comprehensive comparison of metabolomics and proteomics was performed in healthy (without dark spot) and spongy tissue flesh (above 5 % of spongy tissue symptom of flesh area) of 'Keitt ' mango at the commercial harvest stage to explore the potential formation mechanism of spongy tissue. The total 809 metabolites and 129 proteins were identified in mango flesh. Among them, 353 significantly up-accumulated and 28 significantly down-accumulated metabolites, 21 significantly up-accumulated and 12 significantly downaccumulated proteins, mainly participated in ABC transporters, biosynthesis of amino acids, and flavonoid biosynthesis based on KEGG enrichment analysis. Moreover, lignin biosynthesis, polyamine metabolism, and tyrosine biosynthesis were greatly involved in spongy tissue formation. In spongy tissue of mango, syringyl lignin was a main component in lignin due to its significant accumulation. Our results demonstrated that putrescine, cadaverine, spermidine, and spermine as well as GABA, increased in spongy tissue, so as to enhance absorption, assimilation and uptake of nitrogen. Combined with proteomics analysis, polyphenol oxidase may be responsible for the source of brown compounds in mango spongy tissue rather than peroxidase, and tyrosine accumulation was also main component brown compounds. Collectively, the wet and low oxygen condition were the dominating factor for the spongy tissue of 'Keitt ' mango during fruit ripening, subsequently, PPO oxidant reaction with phenols, the peroxidation linoleic and other 17 free fatty acids, enhanced nitrogen absorption and assimilation, and pectin degradation were the crucial metabolism pathways impelling spongy tissue formation of mango fruit. Therefore, our findings provide mechanistic insights into spongy tissue formation of mango fruit, and benefit for the development of mango industry.

Mango (Mangifera indica L.) has been widely cultivated as a culturally and economically significant fruit tree for roughly 4000 years. Despite its rich history, little is known about the crop's domestication, genomic variation, and the genetic loci underlying agronomic traits. This study employs the whole-genome re-sequencing of 224 mango accessions sourced from 22 countries, with an average sequencing depth of 16.37x, to explore their genomic variation and diversity. Through phylogenomic analysis, M. himalis J.Y. Liang, a species grown in China, was reclassified into the cultivated mango group known as M. indica. Moreover, our investigation of mango population structure and differentiation revealed that Chinese accessions could be divided into two distinct gene pools, indicating the presence of independent genetic diversity ecotypes. By coupling genome-wide association studies with analyses of genotype variation patterns and expression patterns, we identified several candidate loci and dominant genotypes associated with mango flowering capability, fruit weight, and volatile compound production. In conclusion, our study offers valuable insights into the genetic differentiation of mango populations, paving the way for future agronomic improvements through genomic-assisted breeding.

MADS-box genes play a crucial role in fruit ripening, yet limited research has been conducted on mango. Based on the conserved domains of this gene family, 84 MADS-box genes were identified in the mango genome, including 22 type I and 62 type II MADS-box genes. Gene duplication analysis revealed that both tandem duplication and segmental replication significantly contributed to the expansion of MADS-box genes in the mango genome, with purifying selection playing a vital role in the segmental duplication events within the MiMADS gene family. Cis-acting element analysis demonstrated that most MiMADS genes were hormonally regulated and participated in the growth, development, and stress resistance of mango fruit. Moreover, through expression pattern analysis and phylogenetic tree construction, we identified six MiMADS genes belonging to the SEP1 subfamily and two belonging to the AG subfamily as potential candidates involved in mango ripening regulation. Notably, Mi08g17750 and Mi04g18430 from the SEP1 subfamily were identified as key regulators inhibiting mango fruit maturation; their interaction network was also analyzed. These findings provide a foundation for further investigation into the regulatory mechanisms underlying mango ripening.

攀育2号杧果是从乳杧实生后代群体中筛选出的杧果新品种.树势强壮,枝条直立.果实椭圆形,果粉厚,肉质滑腻,风味浓甜,纤维极少,口感好,鲜食品质佳.单果质量307.0～369.0 g,可食率79.0%～85.4%,可溶性固形物含量(w,后同)18.3%～21.7%,总糖含量13.80%～16.96%,总酸含量0.061%～0.576%,维生素C含量13.6～70.3 mg·kg-1,β-胡萝卜素含量5.78×104 μg·kg-1.四川攀枝花地区果实发育期120～150 d,中熟,成熟期为7月下旬至8月中旬.高接树第2年初结果,大树改接换冠后3～5 a(年)每666.7 m2平均产量为1384.5 kg.中抗畸形病和细菌性黑斑病.适宜在四川金沙江干热河谷种植.

Mango fruits are susceptible to diseases, such as anthracnose, during fruit development, leading to yield reduction. Epicuticular wax is closely related to resistance of plants to pathogenic bacterial invasion. In this study, the effect of mango fruit epicuticular wax on the invasion of Colletotrichum gloeosporioides was investigated, followed by to understand the changes of wax chemical composition and crystal morphology during mango fruit development using GC-MS and SEM. Results showed that the epicuticular wax of mango fruits can prevent the invasion of C. gloeosporioides, and ‘Renong’ showed the strongest resistance to C. gloeosporioides. The wax content of four mango varieties first increased and then decreased from 40 days after full bloom (DAFB) to 120 DAFB. In addition, 95 compounds were detected in the epicuticular wax of the four mango varieties at five developmental periods, in which primary alcohols, terpenoids and esters were the main wax chemical composition. Furthermore, the surface wax structure of mango fruit changed dynamically during fruit development, and irregular platelet-like crystals were the main wax structure. The present study showed the changes of wax content, chemical composition and crystal morphology during mango fruit development, and the special terpenoids (squalene, farnesyl acetate and farnesol) and dense crystal structure in the epicuticular wax of ‘Renong’ fruit may be the main reason for its stronger resistance to C. gloeosporioides than other varieties. Therefore, these results provide a reference for the follow-up study of mango fruit epicuticular wax synthesis mechanism and breeding.

Spongy tissue, as one of internal flesh breakdown in mango fruits, is correlated with calcium (Ca) deficiency, and adversely affects fruit quality and yield worldwide. However, the underlying mechanism causing spongy tissue remains unknown. Here, we explored the effects of Ca deficiency on spongy tissue in a susceptible cultivar, ‘Keitt’, at the physiological and molecular levels. Nutrient analysis showed that flesh with spongy tissue had lower Ca content and higher N/Ca, K/Ca and Mg/Ca rations than healthy fruit flesh. Ca accumulation in the cell wall, especially in chelator-soluble pectin, was elevated due to increased pectin content, lower levels of pectin methylesterification, and increased pectin methylesterase (PME) activity. During spongy tissue development, levels of Ca oxalate (CaOx) and oxalic acid both increased, whereas soluble Ca content decreased in the flesh. Transcriptomic analysis of healthy flesh and flesh with spongy tissue revealed 2054 up-regulated and 996 down-regulated genes. Gene ontology term analysis showed that the up-regulated genes were mainly enriched in functions related to the transmembrane transporter activity, calcium ion binding, and the cell wall. Importantly, up-regulated genes in spongy tissue included five glucuronate 4-epimerase (GAE) genes and two galactosyltransferase (GALT) genes, which involved in pectin synthesis; four PME genes which control pectin demethylesterification; and eight autoinhibited calcium-transporting ATPase (ACA) genes and two vacuole H+/Ca2+ exchanger (CAX) genes which contribute to Ca influx in the vacuole. Our findings illustrate a mechanism by which Ca deficiency leads to spongy tissue, which will contribute to efforts to control this physiological disorder.

【Objective】Mango（Mangifera indica L.） is an important tropical and subtropical fruit and one of the fifth famous fruits in the world. Cross breeding is an important method for breeding new mango cultivars. At present, some cultivars have been bred through hybridization breeding. However,less attention has been paid to the genetic trend of fruit quality traits in mango hybrid progenies. It is necessary to explore the inheritance of internal quality traits in the fruits of mango hybrid population.Therefore, this experiment was carried out to uncover the inheritance of fruit quality traits including sugar, acid, carotenoids and total flavonoids, in order to provide a scientific basis for the selection of parents in cross breeding.【Methods】Forty-seven individuals of F 1 population derived from a cross between Jinhuang（female, high-sugar variety） and Renong No.1（male, low-sugar variety） were used as materials. Mature fruits were collected in 2021, then stored at room temperature, and fully ripen fruits were used for fruit internal quality analysis. Fifteen fruits from each tree were sampled, and divided into three biological replicates for quality traits measurement. The contents of sucrose, fructose, glucose,ascorbic acid, acetic acid, formic acid, citric acid, oxalic acid, tartaric acid and maleic acid of the fruits were determined with high performance liquid chromatography（HPLC） method. The contents of carotenoids and total flavonoids were determined by UV spectrophotometer. The genetic variations of the fruit traits were evaluated by coefficient variation（CV）, genetic transmitting ability（Ta） and heterobeltiosis, and frequency distribution map was used to investigate the inheritance tendency of the progenies.The data were processed using Microsoft Excel 2016.【Results】The sucrose, fructose and glucose were the main sugar components, the ascorbic acid, malic acid, acetic acid and citric acid were the main organic acid components in the fruits of the parents and their F 1 offsprings. The individuals of the F 1 populations exhibited a wide phenotypic variation in the sugar（sucrose fructose, glucose and total sugar）, acids（ascorbic acid, malic acid, acetic acid, citric acid, formic acid, oxalic acid, tartaric acid and total acids）, carotenoids and total flavonoids. The average coefficients of variation of the sugar and acid contents were over 32.88% and 140.53% respectively, and the range of acid contents was higher than that of sugar contents, indicating that there was a bigger selecting potential for the acid content. The coefficients of variation of the carotenoids and total flavonoids were 51.68% and 38.2% respectively, indicating that carotenoids had greater selection potential. Additionally, the genetic transmitting ability（Ta） of the sugars, acids, carotenoids and total flavonoids ranged from 9.73% to 222.52%（ascorbic acid）, indicating that the variations of these traits mainly determined by the inheritance. The total sugar contents of progenies were higher than mid-parental value, and the super parent rate was over 38.30%, displaying obvious heterosis. However, the total acid contents inclined to low acid parent value, and the superlow parent rate was over 57.45%, showing a tendency of depression. There were more individual plants with higher content of carotenoids compared with the parents, and its super parent rate was 65.96%.The average flavonoids content of progenies was lower than that of the parents, and the low parent rate was 53.19%. The distributions of the total sugar, carotenoids and total flavonoids in the F 1 progenies were close to the normal distribution, indicating that these three traits were quantitative traits controlled by multiple genes. Nevertheless, the acid content of the hybrid offsprings displayed skewed distribution, implying that the acid contents might be controlled by one or more major genes.【Conclusion】The sugar, carotenoids and total flavonoids were quantitative traits controlled by multiple genes, whereas the organic acids were quantitative traits controlled by one or more major genes. The contents of sugar and acid in the fruits of mango hybrid progenies were closer to the parent with high-sugar and low-acid content, and were prone to be affected by the female parent, the inheritance of the carotenoids was inclined to the high value parent, and was greatly influenced by the male parent. The inheritance of the total flavonoids tended to be similar to the low-value parent, and was prone to be influenced by the female parent.

Mango flowering is highly sensitive to temperature changes. In this research, the maximum values of pollen germination rate (PGR), pollen tube length (PTL) and their cardinal temperatures (Tmin, Topt and Tmax) were estimated by using quadratic equation and modified bilinear model under the conditions of 14–36 °C. The pollen germination rate in four mango varieties ranged from 29.1% (‘Apple mango’) to 35.5% (‘Renong No. 1’); the length of pollen tube ranged from 51.2 μm (‘Deshehari’) to 56.6 μm (‘Jinhuang’). The cardinal temperatures ranges (Tmin, Topt and Tmax) of pollen germination were 20.3–22.8 °C, 26.7–30.6 °C and 30.4–34.3 °C, respectively; similarly, cardinal temperatures (Tmin, Topt and Tmax) of pollen tube growth were 20.3–21.2 °C, 27.9–32.1 °C and 30.2–34.4 °C respectively. Of those, ‘Renong No. 1’ could maintain relatively high pollen germination rate even at 30 °C, however, ‘Deshehari’ had the narrowest adaptive temperature range. These results were further confirmed by changes of superoxide dismutase, catalase activity and malondialdehyde content. These results showed that mango flowering was highly sensitive to temperature changes and there were significant differences in pollen germination rate and pollen tube length among different varieties. Current research results were of great significance for the introduction of new mango varieties in different ecological regions, the cultivation and management of mango at the flowering stage and the breeding of new mango varieties.

Introduction Flavonoids are important water soluble secondary metabolites in plants, and light is one of the most essential environmental factors regulating flavonoids biosynthesis. In the previous study, we found bagging treatment significantly inhibited the accumulation of flavonols and anthocyanins but promoted the proanthocyanidins accumulation in the fruit peel of mango ( Mangifera indica L.) cultivar ‘Sensation’, while the relevant molecular mechanism is still unknown. Methods In this study, RNA-seq was conducted to identify the key pathways and genes involved in the light-regulated flavonoids biosynthesis in mango peel. Results By weighted gene co-expression network analysis (WGCNA), 16 flavonoids biosynthetic genes were crucial for different flavonoids compositions biosynthesis under bagging treatment in mango. The higher expression level of LAR ( mango026327 ) in bagged samples might be the reason why light inhibits proanthocyanidins accumulation in mango peel. The reported MYB positively regulating anthocyanins biosynthesis in mango, MiMYB1 , has also been identified by WGCNA in this study. Apart from MYB and bHLH, ERF, WRKY and bZIP were the three most important transcription factors (TFs) involved in the light-regulated flavonoids biosynthesis in mango, with both activators and repressors. Surprisingly, two HY5 transcripts, which are usually induced by light, showed higher expression level in bagged samples. Discussion Our results provide new insights of the regulatory effect of light on the flavonoids biosynthesis in mango fruit peel.

Mango (Mangifera indica L.) is a climacteric tropical fruit consumed around the world. Although ethylene and abscisic acid (ABA) have been considered to be stimulators that trigger mango fruit ripening, their regulation mechanisms in modulating mango fruit ripening remain uncertain. In this study, we performed integrative analyses of metabolome and transcriptome data combined with a series of physiological and experimental analyses in the 'Keitt' mango, and we characterized changes in accumulation of specific metabolites at different stages during fruit development and ripening, which were strongly correlated with transcriptional changes and embodied physiological changes as well as taste formation. Specifically, we found that ABA, rather than ethylene, was highly associated with mango ripening, and exogenous ABA application promoted mango fruit ripening. Transcriptomic analysis identified diverse ripening-related genes involved in sugar and carotenoid biosynthesis and softening-related metabolic processes. Furthermore, networks of ABA- and ripening-related genes (such as MiHY5, MiGBF4, MiABI5, and MibZIP9) were constructed, and the direct regulation by the key ABA-responsive transcription factor MiHY5 of ripening-related genes was experimentally confirmed by a range of evidence. Taken together, our results indicate that ABA plays a key role in directly modulating mango fruit ripening through MiHY5, suggesting the need to reconsider how we understand ABA function in modulating climacteric fruit ripening.