Screening And Identification Of The Banana (Musa Spp.) Mutant Characterized With Pilose Fruit And Early Flower And Primary Study On Its Mechanism

Banana (Musa spp.) is one of the most important fruits around the world. It is also the staple food for nearly 500 millions people and ranks the fourth food crop in the world. In China, banana takes important share of the tropical and subtropical agriculture. Most of the cultivated bananas are triploid. Genetic improvement in cultivated bananas is difficult due to the absence of sexual reproduction mechanisms. And the study on the banana breeding mechanism is also limited. During a long period, the induced mutations play a very important role in the banana breeding.The pilose fruit chimera is one mutant in"Baxi"banana (Musa ssp."Cavendish"AAA). It is characterized with the rachis, fruit and bract was combined by hairy and hairless phenotypes. Using the sucker of this chimera as explant, we obtained separated plantlets of three phenotypes, including pilose fruit, chimera and hairless. Being in vitro cultured and screened for four times, the characteristics of the early-flower/pilose fruit mutant are stable.This early-flower/ pilose fruit mutant was similar to"Baxi"banana on plant general appearance and fruit quality. However, the pericarp, fruit stalk, bract and upside of the bract scars on rachis of the mutant were all covered with trichomes. Another significant characteristic of this mutant was that it flowers 3 months earlier than"Baxi"banana. Compared with"Baxi"banana, the mutant was dwarf and had lower yield.The normal trichomes of the mutant were distributed irregularly and divided into two discrete types. One was long trichome which length and density were 0.17～0.37mm and 16cm-2 respectively. The other was short trichome with length of 0.02～0.07mm and density of 190cm-2. Neither of the long and short trichomes have no branch. They are both straight and with inflated tips. The trichomes on the pericarp of tail banana showed more types--trichomes with branch, trichomes that look like balloon and gourd, and beadlike trichomes with 2～9 knots. The development of the trichomes was in a wave down the bunch. On the pericarp of 49th hand, there were only a few very young trichomes. At maturity, the trichomes wilted and partially cast. By investigation, we found that the density of common thrips and the scars they punctured in the mutant bunch were both less than that of"Baxi".The ISSR and SSR analysis of the genome DNA of mutant and"Baxi"could show polymorphism but with only a few polymorphism bands.The AFLP analysis was used to identify the polymorphism between the mutant and the...