Comparative Biochemical And Transcriptome Analysis Provides Insights Into The Regulatory Mechanism Of Striped Leaf Albinism In Arecanut (Areca Catechu L.)

Frequent striped leaf albinism occurring in young seedlings leads to production loss of arecanut (Areca catechu L.) industry. Previous efforts has proved that this albinism phenotype was determined by genetic factors. However, the mechanism underlying albinism in arecanut remains unclear. In this study, to elucidate the regulatory mechanism of striped leaf albinism, comparison analysis was performed between leaves of normal and albinotic seedlings at physiological, biochemical and transcriptomic levels in arecanut. The albinotic leaves showed obvious degeneration in chloroplast, low chlorophyll content and reduced photosynthetic capacity. More than 5000 DEGs (differentially-expressed genes) was identified between normal and albinotic leaves. Among them, genes involved into the biosynthesis of chlorophyll, carotenoid and anthocyanin were significantly down-regulated in albinotic leaves. On the contrary, genes involved in leaf senescence and ABA (abscisic acid) synthesis were up-regulated in albinotic leaves. Unexpectedly, most genes involved in chloroplast development were up-regulated in albinotic leaves, indicating different regulatory mechanism of albinism in arecanut. Furthermore, transcription factor family genes, such as AP2/ERF-ERF (APETALA2/ethylene responsive factor), NAC (NAM/ATAF/CUC) and WRKY, were identified as DEGs between normal and albinotic leaves, which also indicated the senescence of albinotic leaves. The results indicated that the albinism mechanism of arecanut is different with those reported in other plants. Thus our data provides new insights into the mechanism underlying albinism. The genes related to albinism of arecanut identified in this study would be important targets for genetic modification or molecular markers development, which will be critical for improving the cultivation efficiency of this cash crop.