Transcriptome analysis of the effects of foliar water application on the nap time of mango leaves

Abstract

Abstract [Objective] In order to reveal the molecular mechanism of photosynthetic midday-depression broken by water spring, the effects of continuous spraying on mango leaves were studied by omics technology. This study can provide basis for further optimizing water management to achieve the best consequences, and will have theoretical significance in enhancing mango yield and quality by aligning with the national policy objectives of reducing fertilizer usage and improving efficiency. [Methods] Mango cultivar “Tainong No. 1” in Yuanjiang was used as material. The mango in the fruiting stage was sprayed by water for three times during the midday depression (12:30-14:10), 20 minutes each time, with no water spraying as the control. The leaves were collected for transcriptome sequencing analysis. GO and KEGG databases were used to analyze the differentially expressed genes (DEGs). Analysis of gene expression was conducted by using DESeq, with |log2αFC| >1 and P <0.05 for DEG screening. [Results] 3 789, 2 885, and 1 667 differentially expressed genes were obtained from three development stages, respectively. GO analysis found that the DEGs were highly correlated with the membrane, intrinsic components of the membrane, components of the membrane and other items in the classification of cell components. KEGG analysis showed that the DEGs were mainly enriched in the pathways of plant hormone signal transduction, MAPK signal pathway, circadian rhythm, metabolism of amino sugar and nucleotide sugar, flavonoid biosynthesis, photosynthetic biological carbon fixation, biosynthesis of cutin, sulfite, and wax, metabolism of porphyrin and chlorophyll, starch and sucrose metabolism, and glyceride metabolism. According to the enrichment results, eight differentially expressed genes were screened. With qRT-PCR verification, the gene expression trend was generally consistent with the results of RNA-seq. [Conclusion] The delayed expression of CAO and POR genes suggests that water spraying can prolong chlorophyll synthesis time. Expression of genes encoding FBP and SBP is slightly decreased, suggesting that water spray may regulate gene expression and ease photosynthetic “midday-depression”, which is beneficial to carbon assimilation and photosynthetic efficiency.

Keywords

• mango
• photosynthetic midday-depression
• transcriptome
• biosynthesis of chlorophyll
• carbon fixation in photosynthetic organisms