| Summary: | 博士 === 國立嘉義大學 === 農業科學博士學位學程 === 105 === Musa species (spp.) are monocotyledons. The genus Musa in the family Musaceae is a perennial crop. Depending on genome type, bananas are classified into genome groups AA, AB, BB, AAA, AAB, ABB, BBB, AAAA, and AAAB. Plants and fruit bunches vary in size, color, shape, and yield across different Musa genome groups. In this study, the morphological characteristics of 62 banana germplasm collections were identified and the genetic diversity of these germplasm collections examined. Using amplified fragment length polymorphism (AFLP) DNA fingerprinting, the 15 qualitative morphological descriptors of M. acuminate and M. balbisiana and the 50 morphological characteristics adapted from International Union for the Protection of New Varieties of Plant (UPOV) codes were all employed to morphologically classify 19 Musa spp. and cultivars and elucidate their phylogenetic relationships. AFLP primer pairs were used to generate 6,348 DNA segments, of which 6,113 exhibited polymorphic changes (96.3%). Principal component analysis (PCA) based on the 15 qualitative morphological descriptors of M. acuminate and M. balbisiana indicated that principal components (PC) 1 and 2 explained 78.6% of the variance, whereas that based on the 50 morphological characteristics adapted from UPOV Codes suggested that PC1 accounted for 80.6% of the variance. Pseudostem length, leaf length, and pedicel length were the main variables causing the variance. Morphological and AFLP analyses indicated that bananas in A-genome groups were in the same cluster. The PCA suggested that ‘Pei Chiao’, ‘Giant Cavendish’, and ‘Dwarf Cavendish’ were fairly similar. The AFLP analysis revealed that ‘Pei Chiao’ had a similarity coefficient of 0.99 with ‘Giant Cavendish’ and 0.97 with ‘Dwarf Cavendish’, suggesting that these three species are highly phylogenetically related. The analysis of E-TAC/M-GTG primer pairs indicated that in comparison with ‘Giant Cavendish’ and ‘Dwarf Cavendish’, ‘Pei Chiao’ had both 255- and 238-bp specific DNA bands. ‘Pei Chiao’, ‘Giant Cavendish’ and ‘Dwarf Cavendish’ belonged to the AAA cluster; although slight molecular polymorphism existed among them and can be used to distinguish among similar species. PCA of the 15 qualitative descriptors of M. itinerans var. formosana showed that this variant was placed in a cluster different from that of M. acuminate, M. balbisiana, and other Musa cultivars, indicating a weak phylogenetic relationship. A cluster analysis through AFLP yielded a similar result, finding that the genetic similarity of M. itinerans var. formosana with M. acuminate, M. balbisiana, and other Musa cultivars was only 0.23. M. itinerans var. formosana had 133 specific bands—the most among all specimens—and a significantly different genetic composition from other banana species. Musa spp. and cultivars with different ploidy levels and genomic constitutions were hybridized, and the efficiency of their hybridization and the yield of hybrid seeds from the hybridization were estimated. Hybrid seeds were obtained from the hybridization of ‘Dwarf Cavendish’, ‘Monkey’, and ‘Pelipia’ (all of which are triploids) as female parents. Few hybrid seeds were produced by hybridizing ‘Dwarf Cavendish’ with the pollen of M. balbisiana. No hybrid seeds were obtained from hybrids with ‘Pei Chiao’ as the female parent with the pollen of M. balbisiana. Hybridization of M. itinerans var. formosana as the female parent with the pollen of M. balbisiana yielded no seed, whereas hybridization of M. itinerans var. formosana as the male parent with M. balbisiana yielded hybrid seeds. Hybrids between triploid cultivars and the pollen of diploid wild species produced a few hybrid seeds, some of which had an irregular or deformed appearance. By contrast, hybrids with diploid wild species as female parents yielded more hybrid seeds, most of which had a normal appearance. However, some of these hybrid seeds contained no embryo or endosperm, whereas others contained deformed embryos and endosperms. As such, the production of hybrid seeds does not necessarily indicate successful propagation. The findings of this study may inform the classification of banana germplasm accessions, the selection of hybrid parents, and the breeding of bananas.
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