PbrARF4 contributes to calyx shedding of fruitlets in ‘Dangshan Suli’ pear by partly regulating the expression of abscission genes  

作　　者：Guoling Guo Pengfei Wei Tao Yu Haiyan Zhang Wei Heng Lun Liu Liwu Zhu Bing Jia 

机构地区：[1]School of Horticulture,Anhui Agricultural University,Hefei,Anhui 230036,China [2]Huayuan Foreign Language School,Zhejiang Normal University,Jinhua,Zhejiang 322100,China [3]Agricultural Experimental Center of Guiyang,Guiyang Agriculture and Rural Bureau,Guiyang,Guizhou 550018,China

出　　处：《Horticultural Plant Journal》2024年第2期341-354,共14页园艺学报（英文版）

基　　金：supported by the China Agriculture Research System (Grant No.CARS-28-14)。

摘　　要：Fruitlet calyx shedding in pear plants is apparently regulated via numerous pathways that involve both environmental triggers and phytohormones cues such as auxin. In this study, we found at 10 days after full bloom (DAFB) higher levels of indoleacetic acid (IAA) and tryptophan (Trp) in calyx persistence fruitlet (CPF) than calyx shedding fruitlet (CSF) ofDanshan Suli’ pear (Pyrus bretschneideri Rhed.). Consisting with this, the activity of indolealdehyde oxidase (IAAIdO), which promotes IAA synthesis, was remarkably increased, and that of peroxidase(POD), which degrades IAA, dropped markedly in CPF but not in CSF. Further, qRT-PCR results revealed that most of 31 PbrARFs (encoding auxin response factors) in Pyrus bretschneideri were highly expressed in CPF, whereas PbrARF4, PbrARF24 and PbrARF26 were significantly downregulated in CPF vis-a-vis CSF. Phylogenetic analysis revealed that 6 PbrARFs clustered in the group III, where PbrARF4 showed the closest affinity with AtARF1 that promotes organ abscission, indicating a putative role of PbrARF4 in mediating the process of calyx shedding in pear. In fact, the ectopic overexpression of PbrARF4 in Solanum lycopersicum resulted in an earlier-formed and deeper abscission layer (AL) in the transgenic plants, whose calyxes were more prone to wilt at the mature red stage (MR) compared with the control plants (wild-type). More importantly, expression levels of the abscission genes SILS and Sl Cel2 in transgenic plants overexpressing PbrARF4 were significantly upregulated in comparation with the WT, whereas those of Sl BI and Sl TAPG2 were considerably inhibited. Further, PbrJOINTLESS and PbrIDA,the two genes related to calyx shedding in pear, were up-regulated more in CSF than CPF. The findings contribute to a better understanding of PbrARFs involved in fruitlet calyx shedding of pear, which could prove beneficial to improving the quality of pear fruit.

关 键 词：PEAR Pyrus bretschneideri Rehd Calyx shedding IAA PbrARF4 Abscission genes 

分 类 号：S661.2[农业科学—果树学]