Kiwifruit (Actinidia chinensis) is a perennial horticultural crop species, and has a relatively high-quality genome. Its richness in vitamin C, minerals, dietary fiber, and other nutrients provide health benefits, thus giving the fruit an enormous nutritional and economic value. However, pathogen stress is destructive and economically damaging for kiwifruit; thus, it is of great significance to study the stress resistance mechanism of kiwifruit.

Supervised by Prof. ZHANG Xiujun and research assistant ZHANG Aidi, XIONG Yuhong from the Wuhan Botanical Garden of the Chinese Academy of Sciences analyzed Multiple Organellar RNA Editing Factor (MORF) family in Kiwifruit and its roles in chloroplast RNA editing and pathogens stress.

They identified ten MORF genes in the kiwifruit genome, which consisted of three conserved motifs, and distributed cross seven linkage groups and one contig.

The phylogenetic analysis indicated that all MORF genes were into six clades and designated as Groups A- F. The synteny analysis revealed that five pairs of MORF genes were assigned to segmental duplication events, and two pairs of MORF genes were tandemly duplicated.

Moreover, the examination of MORF genes tissue expression profiles showed that MORF genes of kiwifruit demonstrated tissue-specific patterns. The tissue-specific expression of MORF genes probably contributed to the discrepancy in RNA editing, such as high expression of MORF2 and MORF9 in leaf and shoot.

MORF genes demonstrated differential expression and different RNA editing patterns between resistant and susceptible kiwifruits under pathogen stress, indicating MORF genes regulated stress response by modulating the editing extend of mRNA.

These results provide further information of the properties and biological functions of MORF genes, and enlighten the defense mechanisms of kiwifruit during pathogen infection.

This research was funded by the National Natural Science Foundation of China and the National Science & Technology Innovation Zone Project. Results have been published on Plants entitled "Genome-Wide Analysis of Multiple Organellar RNA Editing Factor (MORF) Family in Kiwifruit (Actinidia chinensis) Reveals its Roles in Chloroplast RNA Editing and Pathogens Stress".

Expression and RNA editing pattern of MORF genes in kiwifruit among different tissues. (Image by WBG)