The Preliminary Study Of Functions Of HXK Gene Family During Ripening In Banana Fruit

Banana (Musa spp.) is one of the most important fruit in the world, the fresh fruit sales reached first in the world. But the banana storage after picking seriously affects the development of the banana industry. One of the main reasons is that the banana fruit is a more respiratory climacteric fruit, it’s not easy to store. Previous studies showed that Hexokinase is Sugar receptor in an organism could catalyzed the phosphorylation of Hexoses including Glucose and Gructose and be able to participate in the sugar signal transduction of a variety of plant.The HXK gene family was searched in NCBI and Banana Genome Hub according to the homology,we got the sequence information of the HXK gene family. Make Brazil banana to be the research object, show the the transcription expression analysis of HXK gene family members in the flesh and peel of banana through the RT-PCR technology. We obtain the data of HXK activity detection、endogenous ethylene synthesis and HXK gene family members transcription analysis after ethephon、mannose、NAG、1-MCP treatment. We want to know the relationship between HXK gene family and ethylene biosynthesis. in postharvest banana ripening process and clarify the function of HXK gene family in the banana ripening process, the results are as follows:(1) The results of searching Banana HXK gene family through the NCBI and the Banana Genome Hub show that:Banana HXK gene family consists of 11 members. In this experiment were named for HXA123, HXB1/2/3/4 and HXC1/2/3/4. At the same time, the 11 members of the family of PCR primers designed specifically were cloned and verified in banana pulp and peel were failed to detect the expression of HXB1 and HXA1.(2) There were different expressions of HXK gene family members in postharvest banana ripening (CK). Overall, the expression changes of HXK gene family in the flesh is more abundant, the relative expression of HXC3 and HXB2 were the most prominent.(3) Under different treatment HXK expression analysis showed that: ① NAG treatment, in the flesh of NAG significantly inhibited the expression of HXB2 and HXC2/3/4, promoted the expression of HXB3; in the peel NAG inhibited the expression of HXC2/3, and promoted the expression of HXB4. ②Most members of HXK gene family of ethephon treatment group in pericarp tissues was up-regulated induced by ethephon.③ Mannose treatment, the expression of HXC1, HXB3 and HXA3 was induced, the expression of HXC3 was inhibited in the flesh, and the expression of HXB3/4, HXC2, HXA3 and was induced and the expression of HXC3 was inhibited in the peel. ④ 1-MCP inhibits the expression of most members of the HXK gene family.(4) Treated with Ethephon showed that ethylene increased HXK activity; 1-MCP treatment group showed that HXK activity was inhibited in the absence of endogenous ethylene; Mannose protected the banana ethylene synthesis and improved the HXK activity. The HXK activity was affected by the endogenous ethylene or ethylene signal pathway.(5) Ethylene/mannose induced the endogenous ethylene synthesis significantly, and ethylene induced ability is higher than mannose; NAG and 1-MCP inhibited the endogenous ethylene synthesis significantly, and 1-MCP has a better effect.(6) In addition to HXB2/HXC3, The HXK related to banana ripening in the form of energy though EMP, there may be a non ATP link relationship between HXB2/HXC3 and the ethylene biosynthesis, and HXB3/4 maybe in upstream of ethylene biosynthesis pathway,the ethylene biosynthesis plays a key role in banana ripening.and induces high expression of EMP key HXK; Pericarp tissue may play a more important role in the banana ripening.