| Banana (Musa spp.) is a monocotyledonous plant, which is evergreen and perennial. Besides banana is the fifth important trade crop in the world, and China is one of the major banana producing countries. Most bananas are polyploidy. Their low pollen fertility and preference of asexual reproduction make crossbreeding of banana difficult to conduct.This study was based on National Fruit Trees Germplasm Resources--Banana Garden, Ministry of Agriculture. We chose the excellent parental resources introduced from the International Banana Genebank, and used them as materials to carry out a preliminary study of the banana crossbreeding. A technology system suitable for Chinese banana crossbreeding was establishment.The main content of this study and results are as follows:(1) Detection of pollen viability from different species. Four diploid banana germplasm with high fertility were selected as meterials, which were’Calcutta4’(AA), Malaccensis (AA), Balbisiana (BB) and’SH-3142’(AA). We tested the pollen viability of each sample, and compared the results of in vitro germination methods and different staining method. MTT method had the best detection effect, consider the reliability, convenience and promptitude. We selected MTT method to test the pollen viability of17diploid banana samples in the resources garden. The pollen staining rate of ’Calcutta4’ was89.92%, which is the highest among all samples. The pollen staining rate was lower than30%in three improved diploid germplasm and four cultivate type germplasm.(2) Hybridization and acquisition of the hybrids. The hybridization experiments were conducted. We chose’Calcutta4’(AA) as male parent since it had the highest pollen viability. Female parent were’GuangFen NO.1’(Musa.ABB Pisang awak) and ’ZhongFen NO.1’(Musa.ABB Pisang awak), respectively. The growth and development process of the hybrid embryos were observed. We carried out the research of embryo rescue, embryo culture and seedling growth of those hybrids. The suitable medium for embryo culture was MS macro-and micro-nutrients, vitamins of Morel,500mg/L casein hydrolysate,25g/L sucrose,8g/L agarose, lmg/L6-BA and0.4mg/L IAA. In crossbreeding experiments, we have got946seeds from hybridization combination of ’ZhongFen NO.1’(Musa.ABB Pisang awak) x’Calcutta4’(AA) and1626seeds from hybridization combination of’GuangFen NO.1’(Musa.ABB Pisang awak) x’Calcutta4’(AA). The embryo rates of the two hybridization combination were28.65%and36.29%, respectively; the germination rates were4.33%and2.21%, respectively; the seedling rate were2.85%and1.29%, respectively. Eventually, we got21and27individual plants respectively from two hybridization combinations, and transferred them to greenhouse for cultivation.(3) Identification of the hybrids. The ploidy of those hybrids were identified through flow cytometry and their inheritance pattens were analyzed. The results showed that the ploidy of the hybridization posterities from’ GuangFen NO.l’(Musa.ABB Pisang awak) x’Calcutta4’(AA) hybridization combination was2x:3x:4x:5x=5:2:11:3, while the ploidy of the hybridization posterities from ’ZhongFen NO.l’(Musa.ABB Pisang awak)×’Calcutta4’(AA) hybridization combination was2x:3x:4x:5x=11:5:9:2. The genome size of those hybridization posterities were range from504Mbp to783Mbp, except for posterities of G18, which was423Mbp. The identification and analysis of genotype combined the method of molecular markers showed that hybridization of diploidx triploid could get posterities of diploid, triploid, tetraploid, ultra-ploid, even non-integer polyploid. Also, abnormal meiosis happened during genotype A and B hybridization could cause polymorphism in genotype among their posterities. |
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