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Article|19 Jan 2022|OPEN
Comparative transcriptomic analysis on compatible/incompatible grafts in Citrus
Wen He1,2 ,† , Rui Xie1,2 ,† , Yan Wang1,2 , , Qing Chen1 , Hao Wang1,2 , Shaofeng Yang1,2 , Ya Luo1 , Yong Zhang1 , Haoru Tang1,2 , Frederick G. Gmitter Jr3 , Xiaorong Wang,1,2 ,
1College of Horticulture, Sichuan Agricultural University, Chengdu 611130, Sichuan, China
2Institute of Pomology and Olericulture, Sichuan Agricultural University, Chengdu 611130, Sichuan, China
3Citrus Research and Education Center, University of Florida, Lake Alfred 33850, FL, USA
*Corresponding author. E-mail: wangyanwxy@sicau.edu.cn,wangxr@sicau.edu.cn
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhab072 (2022)
doi: https://doi.org/10.1093/hr/uhab072
Views: 21

Received: 20 Jul 2021
Accepted: 08 Nov 2021
Published online: 19 Jan 2022

Abstract

Grafting is a useful cultivation technology to resist abiotic and biotic stresses and is an integral part of citrus production. However, some widely utilized rootstocks may still exhibit graft incompatibility in the orchard. ‘Hongmian miyou’ (Citrus maxima (Burm.) Merrill) is mutated from ‘Guanxi miyou’, but these two scions showed different compatibility with available Poncirus trifoliata rootstock. Foliage etiolation is an observed symptom of graft incompatibility, but its mechanism remains poorly understood. This study is the first to investigate the morphological, physiological, and anatomical differences between compatible and incompatible grafts, and perform transcriptome profiling at crucial stages of the foliage etiolation process. Based on comprehensive analyses, hormonal balance was disordered, and two rate-limiting genes, NCED3 (9-cis-epoxycarotenoid dioxygenase 3) and NCED5, being responsible for ABA (abscisic acid) accumulation, were highlighted. Further correlation analysis indicated that IAA (indole-3-acetic acid) and ABA were the most likely inducers of the expression of stress-related genes. In addition, excessive starch accumulation was observed in the lamina and midribs of leaves of incompatible grafts. These results provide a new insight into the role of hormonal balance and ABA biosynthesis genes in regulating and contributing to graft incompatibility, and will further define and deploy candidate genes to explore the mechanisms underlying citrus rootstock–scion interactions.