| The new germplasm 'Hongzuanmiyou' is a bud mutant from'Guanximiyou'.To discuss its applied and promoted value,the botanical characteristics were observed,the biological traits were investigated,the cultivation techniques were compared with other pummelo varieties.The traits of pollen were also observed by electron microscopy.The molecular phylogenetic analysis was conducted based on ITS,matK and rbcL sequences.The appearance characteristics of 'Hongzuanmiyou' fruit were analyzed and the content of carotenoids,sugar and organic acids in the fruits were determined by liquid chromatography.The fruit quality of'Hongzuanmiyou' and other pomelo varieties were compared and comprehensively evaluated.1.The botanical characteristics show that the 'Hongzuanmiyou' tree grows well,the shoots have strong germination,the canopy is nearly round-headed,and the leaf layer is thicker,the leaves are an oval unifoliolate compound with near the entire edges,and the tip of the apex is obtuse.One-year-old twigs are green,the spring shoots are slim and short,the autumn shoots are thick and long,the medium length spring shoots are fruiting canes,there are leafy-inflorescence shoots and inflorescence shoots without leaves,the position of fruit setting locates at inner,middle and lower of the canopy.The flowers are white and oval with a refreshing scent.The inflorescence is raceme.There are 5?15 flowers on each inflorescence.There are about 1?4 fruits on each shoot.The fruit shape is obovate and the shape index is 0.90??0.94,the weight of a single fruit is about 1000?1750 g.The longitudinal diameter is 14?16 cm,the transverse diameter is 16?17 cm,the peel is about 1.5 cm thick and easy to peel off,and it has red stripes on ripe fruits.The albedo is white with light yellow stripes and is easy to peel off with the segment wall,the numbers of carpels are 14?16,the segment wall is thin with pale yellow color.The juice sac is silvery white with crisp and delicious.The fruit is seedless with a small number of aborted seeds.The biological traits show that‘Hongzuanmiyou,began to sprout and shoot in the first half of March,and appeared in the middle of March.It began to bloom in early April,in full boom mid-April and bloomed in the first half of May.There were 2 physiological drops in mid-May and in early June.The fruit coloring period is mid-to-late August.The fruit matures in the middle and late November.The maturity is 15?30 days later than 'Guanximiyou' which planted in the same field.It was found that the cultivation techniques of 'Hongzuanmiyou' are the same as 'Guanximiyou',and the requirements for light,moisture,soil,and topography are also the same as those of 'Guanximiyou',but the disease resistance is stronger than 'Guanximiyou'.It was currently found that the pest and diseases are mainly eucalypti,red spider,aphid,thrips and fungi diseases.2.The results of scanning electron microscopy showed that the pollen grains of 'Hongmianmiyou'existed in a single form.The pollen grains were full and spherical,axisymmetric and arc-shaped,which belonged to small and medium-sized pollen,and the ratio of polar axis length to red axis length was 0.94.The outer wall of the pollen has a fine mesh pattern.The mesh ridge is flat and smooth or has an inconspicuous bulge.The mesh is shallow and has an irregular small perforation.The equatorial mesh is sparse,the mesh ridge is smooth,and the polar mesh isclosely distributed with the smoother ridge.The germination hole of'Hongzuanmiyou' pollen is a typical long-shaped germination hole with a ring-shaped germination groove.The spurted germination holes are evenly distributed on the surface of the pollen wall,and its long axis is perpendicular to the equatorial plane.The germination groove of'Hongzuanmiyou' is distributed equidistantly along the direction of the polar axis.It is mainly composed of 4 holes and rarely has 5 groove holes.The ratio of 5 groove holes is 8.37%.Compared with the pollen grains of other pomelo varieties,the pollen grains of 'Hongzuanmiyou' have similar size.There is no significant difference between 'Hongzuanmiyou'and other varieties.The overall density of the mesh of 'Hongzuanmiyou'is different from other varieties.The morphology of pollen germination holes is not much different among the varieties,however,the proportion of 5 groove holes have some differences.3.Based on the ITS,matK and rbcL sequences,19 citrus materials such as 'Hongzuanmiyou' were analyzed for genetic relationship.The results showed that the 6 pair primers were screened from 10 pair primers.The selected primers were employed to PCR amplification and the results were sequenced.The phylogenetic tree was constructed based on the gene sequences.The results showed that the sequences ITS1,ITS2,and rbcL3 were suitable for the phylogenetic relationship of citrus materials such as'Guanximiyou'.According to the phylogenetic trees,they were found that ' Hongzuanmiyou' has a close relationship with ' Guanximiyou' and its bud mutants,but has different from other varieties.The results showed that 'Hongzuanmiyou,is a new germplasm mutant from 'Guanximiyou'.4.The UPLC technology was used to detect the main components and contents of carotenoids in different tissues and different developmental stages of 'Hongzuanmiyou'.The results showed that the zeaxanthin was detected in segment wall and albedo of 'Hongzuanmiyou'mature fruit with the amounts of 1.65?g/g and 1.43?g/g respectively.Carotenoids were not detected in juice sacs.During the development of different varieties of fruits,the carotenoids have similar increased trends.The pigment contents in the segment wall and albedo were elevatory,however,the contents decrease before the fruit matures,while the pigment content in the juice sacs decreasing during fruit developing.5.The appearance traits of 'Hongzuanmiyou' and other varieties were detected in this study.The results showed that compared with the other 26 materials,'Hongzuanmiyou,has good appearance and fruit shape,and the edible rate is higher than that of other pomelos.The results showed that it has high edible value and economic value.On the basis of the results of correlation analysis and cluster analysis,the 26 citrus samples can be distinguished by appearance traits.It was indicated that the appearance traits of 'Guanximiyou' and other pummelo fruits are unique,and could be used as indicators to discriminate different varieties.6.The content of organic acids and components in citrus fruits was determined by high-performance liquid chromatography-tandem mass spectrometry(HPLC-MS).The results showed that the total acid content of 'Hongzuanmiyou' mature fruit juice was 9.06 mg/g,the content of citric acid is highest with 7.45mg/g,following by pyruvic acid with 0.94mg/g,malic acid 0.30 mg/g,fumaric acid 0.14 mg/g.The content of quinic acid,cis-aconitic acid,succinic acid,and tartaric acid ranged from 0.07 to 0.04 mg/g,which is lower than the others.It was indicated that'Hongzuanmiyou' is a typical citric acid metabolizing fruit.The results of principal component analysis and cluster analysis of organic acids showed that organic acid could be used as an indicator to distinguish different varieties of 'Guanximiyou' strains.7.The UPLC-ELSD method was established to determine the content of fructose,glucose,and sucrose in the fruit of pummelo.In'Hongzuanmiyou' mature fruit juice sacs,the content of total sugar was about 85?75 mg/g,the content of fructose was 21.62 mg/g,the content of glucose was 21.19 mg/g,and the content of sucrose 38.91 mg/g.The ratio of fructose-glucose-sucrose was 1:1:2,it was indicated that the'Hongzuanmiyou' is a typical sucrose accumulation type fruit.The contents of fructose,glucose,and sucrose were all increased during the fruit growth and development,however,the growth of fructose and glucose is slowly.Moreover,the increasing extent of sucrose during the fruit expansion period was higher than that of other stages with more than 2 times.8.The TSS content of 'Hongzuanmiyou' was 13.52%,the lignin content was 0.80%,the Vc content was 51.87 mg/100 g,the sugar-acid ratio was 9.38,and the solid-acid ratio was 14.9.Through the principal component analysis of 13 evaluation indicators,the 4 principal components related to the appearance quality,processing quality and flavor with sugar and organic acid were successfully extracted from 27 fruits,and it was comprehensively evaluated by the membership function.The comprehensive ranking of 'Hongroumiyou' is 8th,indicating that the quality is excellent. |
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