Genetic maps are particularly important and valuable tools for quantitative trait locus (QTL) mapping and marker assisted selection (MAS) of plant with desirable traits. In this study, 173 F1 plants from a cross between Mangifera indica L. ‘Jin-Hwang’ and M. indica L. ‘Irwin’ and their parent plants were subjected to high-throughput sequencing and specific-locus amplified fragment (SLAF) library construction. After preprocessing, 66.02 Gb of raw data containing 330.64 M reads were obtained. A total of 318,414 SLAFs were detected, of which 156,368 were polymorphic. Finally, 6,594 SLAFs were organized into a linkage map consisting of 20 linkage groups (LGs). The total length of the map was 3148.28 cM and the average distance between adjacent markers was 0.48 cM. This map could be considered, to our knowledge, the first high-density genetic map of mango, and might form the basis for fine QTL mapping and MAS of mango.

Aroma is important in assessing the quality of fresh fruit and their processed products, and could provide good indicators for the development of local cultivars in the mango industry. In this study, the volatile diversity of 25 mango cultivars from China, America, Thailand, India, Cuba, Indonesia, and the Philippines was investigated. The volatile compositions, their relative contents, and the intervarietal differences were detected with headspace solid phase microextraction tandem gas chromatography-mass spectrometer methods. The similarities were also evaluated with a cluster analysis and correlation analysis of the volatiles. The differences in mango volatiles in different districts are also discussed. Our results show significant differences in the volatile compositions and their relative contents among the individual cultivars and regions. In total, 127 volatiles were found in all the cultivars, belonging to various chemical classes. The highest and lowest qualitative abundances of volatiles were detected in ‘Zihua’ and ‘Mallika’ cultivars, respectively. Based on the cumulative occurrence of members of the classes of volatiles, the cultivars were grouped into monoterpenes (16 cultivars), proportion and balanced (eight cultivars), and nonterpene groups (one cultivars). Terpene hydrocarbons were the major volatiles in these cultivars, with terpinolene, 3-carene, caryophyllene and α-Pinene the dominant components depending on the cultivars. Monoterpenes, some of the primary volatile components, were the most abundant aroma compounds, whereas aldehydes were the least abundant in the mango pulp. β-Myrcene, a major terpene, accounted for 58.93% of the total flavor volatile compounds in ‘Xiaofei’ (Philippens). γ-Octanoic lactone was the only ester in the total flavor volatile compounds, with its highest concentration in ‘Guiya’ (China). Hexamethyl cyclotrisiloxane was the most abundant volatile compound in ‘Magovar’ (India), accounting for 46.66% of the total flavor volatiles. A typical aldehydic aroma 2,6-di-tert-butyl-4-sec-butylphenol, was detected in ‘Gleck’. A highly significant positive correlation was detected between Alc and K, Alk and Nt, O and L. Cultivars originating from America, Thailand, Cuba, India, Indonesia and the Philippines were more similar to each other than to those from China. This study provides a high-value dataset for use in development of health care products, diversified mango breeding, and local extension of mango cultivars.

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.

Internal flesh breakdown (IFB), a serious physiological disorder of mango fruit, causes significant economic losses in Southwest China. We investigated the extent of IFB in 100 mango orchards and how changes in the mineral nutrients of fruit flesh, leaves and soil affect IFB. We found that 76% of the mango orchards showed IFB symptoms, and the average IFB incidence was 10%. Fruit flesh with IFB showed higher average contents of N, P, K and Mg, lower average Ca content and higher average ratios of N/Ca, K/Ca and Mg/Ca. The leaves from orchards with IFB symptoms exhibited a remarkable increase in the average N and Mg contents. No significant difference was observed in the soil nutrient concentrations between orchards with and without IFB fruit. IFB incidence was significantly positively correlated with the N/Ca, K/Ca and Mg/Ca ratios in the fruit flesh. However, when considering individual orchards with IFB symptoms, fruit flesh that exhibited breakdown symptoms had Ca content higher, lower than or equal to that of the healthy fruit flesh. There was a strong correlation between fruit flesh and leaf in the same mineral elements, but neither of them showed a significant correlation with soil. Considering the mango trees were cultivated on steep slopes, and fertilizer was applied at a fixed position, we hypothesized that long-term fertilization in the partial root zone led to the excess of N, K and Mg in soil, which reduced the total flesh Ca content or resulted in the abnormal cellular distribution of Ca in the flesh, and ultimately triggered IFB development.

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.

Mango (Mangifera indica L.) belongs to the genus Mangifera and family Anacardiaceae, and is an important tropical fruits. Artificial cross breeding (hand pollination) is an important method for breeding new mango cultivars. It is easy to produce false hybrids in the process of artificial pollination breeding. Therefore, it is necessary to establish rapid and accurate molecular detection methods to identify the authenticity of hybrids. Mango ‘Jinhuang’ and ‘Renong No.1′ and 65 individual plants of their F₁ hybrids were used as experimental materials, eight SSRs (simple sequence repeats) primer pairs with polymorphism in parents were used to identify the F₁ hybrids by capillary electrophoresis. The results showed that PCR product size (bp) for eight primers ranged from 108 bp (ES55) to 176 bp (ES63) in 65 samples. A total of 62 true hybrids were identified from 65 hybrid progenies, and the true hybrid rate was 95.38%. A total of 18 alleles were amplified by eight SSRs, seven SSR loci showed binary segregations, whereas only one SSR locus ES83 showing ab:ac:bb:bc segregation fitted to the expected segregation ratio of 1:1:1:1. The value of expected heterozygosity (He), ranged from 0.34 to 0.62, whereas the value of observed heterozygosity ranged from 0.44 to 0.81. Chi-square test showed that eight SSR loci were in accordance with Mendel’s segregation law. The results of cluster analysis showed that the parents and 62 true hybrids could be classified into two categories at 0.58: the first category contained 27 offspring, clustered with ‘Jinhuang’ and showed a maternal genetic tendency. The second category contained 35 offspring, clustered with ‘Renong No.1′ and showed a partial paternal genetic tendency. DNA fingerprint of hybrids from ‘Jinhuang’ × ‘Renong No.1′ cross were constructed using eight SSR primers for variety protection.