Identification Of SPL Gene Family And Analysis Of The Function Of PrupeSPL16,17,19 In The Process Of Fruit Ripening And Softening In Peach

Peach(Prunus persica(L.)Batsch.)fruit has poor storability and is easy to soften and rot after harvesting.It has become one of the problems to be solved urgently in peach production.Clarify the peach fruit softening mechanism,find out the key regulatory factors,and it has great significance for improving peach fruit storability.SPL(SQUAMOSA promoter-binding protein like)gene plays an important role in regulating plant growth and development.In this study,members of the peach SPL gene family were identified,and analyzed the expression characteristics of the SPL family members.Meanwhile,VIGS(Virus induced gene silence)and transient overexpression technology were used to research the function and mechanism of key members PrupeSPL16,PrupeSPL17 and PrupeSPL19 in peach fruit ripening and softening.The main findings are as follows:1.25 PrupeSPL gene family members were identified in peach genome,named PrupeSPL1-25 according to the chromosome location successively.Except that the PrupeSPL16 gene lacks the Zn-2 structure,each PrupeSPL gene contains a conserved SBP domain,two zinc finger structures,and a nuclear localization signal.2.The expression of peach SPL family members shows a certain tissue specificity.PrupeSPL16 and PrupeSPL17 are highly expressed in fruits;PrupeSPL7 and PrupeSPL8 are highly expressed in new shoots;PrupeSPL14/15 are highly expressed in leaves.The majority of PrupeSPL members have low expression levels in roots and flowers,meanwhile,most of them have higher expression levels in young fruit,and their expression level decreases with the fruit growing,but there are certain differences between different varieties.During fruit ripening and softening,PrupeSPL1,3,4,7,8,10,14,15,16,17,19 all showed up-regulated expression trend;while the other PrupeSPL family members' expression was low and stable.Ethylene treatment of ‘Qin Wang' fruit promotes the expression of PrupeSPL10-20;while ethylene treatment of ‘Qian Jianbaitao' fruit significantly promotes the expression of PrupeSPL1-9,13,19 and has little effect on the expression of other PrupeSPL family members.3.The expression levels of PrupeSPL1,3,4,19 were relatively high during the fruit development and ripening stages,and the expression levels increased with the development of the fruits.PrupeSPL16 and PrupeSPL17 had the highest expression during the young fruit period,but the expression decreased as the fruit matured.The expression patterns of SPL family genes have a high similarity,and most PrupeSPL genes are expressed in young fruits with a high level.After ethylene treatment,the expression levels of PrupeSPL2,PrupeSPL 5/6,and PrupeSPL9 at the end of storage were significantly increased.4.The results of yeast single hybrid experiment showed that PrupeSPL16 and PrupeSPL17 proteins can interact with the promoters of Pp ACS2 and Pp ACO1,but not with Pp PG2 and Pp EIN1.This study systematically analyzed the PrupeSPL gene family,which laid an important foundation for further research on the functional characteristics of SPL genes and other genes which regulate fruit ripening during peach fruit development period and ripening.