Baolin Kan, Yong Yang, Pengmeng Du, Xinping Li, Wenjie Lai, Haiyan Hu

PLoS One;  2022 Jun 24; 17(6):e0270610.  doi: 10.1371/journal.pone.0270610.

Abstract

Magnesium (Mg) is an essential macronutrient for plant growth and development. Physiological and transcriptome analyses were conducted to elucidate the adaptive mechanisms to long-term Mg deficiency (MD) in banana seedlings at the 6-leaf stage. Banana seedlings were irrigated with a Mg-free nutrient solution for 42 days, and a mock control was treated with an optimum Mg supply. Leaf edge chlorosis was observed on the 9th leaf, which gradually turned yellow from the edge to the interior region. Accordingly, the total chlorophyll content was reduced by 47.1%, 47.4%, and 53.8% in the interior, center and edge regions, respectively, and the net photosynthetic rate was significantly decreased in the 9th leaf. Transcriptome analysis revealed that MD induced 9,314, 7,425 and 5,716 differentially expressed genes (DEGs) in the interior, center and edge regions, respectively. Of these, the chlorophyll metabolism pathway was preferentially enriched according to Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The expression levels of the five candidate genes in leaves were consistent with what is expected during chlorophyll metabolism. Our results suggest that changes in the expression of genes related to chlorophyll synthesis and decomposition result in the yellowing of banana seedling leaves, and these results are helpful for understanding the banana response mechanism to long-term MD.

See https://pubmed.ncbi.nlm.nih.gov/35749543/

Fig 7

Metabolic network of chlorophyll biosynthesis and degradation in banana leaves.

(A) DEGs identified by RNA-seq are shown in colored blocks. Blue blocks represent downregulated genes, and red blocks represent upregulated genes. (B) qRT-PCR analysis and RNA-seq data of MaCHLI, MaCHLM, MaCHLG, MaSGR1 and MaSGR2 expression.