Transcriptional and physiological analyses of reduced density in apple provide insight into the regulation involved in photosynthesis

• Published in: PloS one 2020-10, Vol.15 (10), p.e0239737
• Main Authors: Niu, Junqiang, Ma, Ming, Yin, Xiaoning, Liu, Xinglu, Dong, Tie, Sun, Wentai, Yang, Fuxia
• Format: Article
• Language: English
• Subjects: Agricultural production; Apples; Biology and Life Sciences; Carbon fixation; Chlorophyll; Chlorophyll - metabolism; Circadian rhythms; Fruit trees; Fruits; Gene expression; Gene Expression Profiling - methods; Gene Expression Regulation, Plant - genetics; Genes; Genetic aspects; Genetic regulation; Genetic research; Leaves; Malus - genetics; Malus - metabolism; Metabolism; Photosynthesis; Photosynthesis - physiology; Photosystem II; Physical Sciences; Physiological aspects; Physiological effects; Physiology; Plant Leaves - metabolism; Planting density; Porphyrins; Research and analysis methods; Signal transduction; Statistical analysis; Transcription; Transcription (Genetics); Transcriptome - genetics; Trees; Variance analysis
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0239737

Different densities have a great influence on the physiological process and growth of orchard plants. Exploring the molecular basis and revealing key candidate genes for different densities management of orchard has great significance for production capacity improvement. In this study, transcriptome sequencing of apple trees was carried out at three different sampling heights to determine gene expression patterns under high density(HD) and low density(LD) and the physiological indices were measured to determine the effect of density change on plants. As a result, physiological indexes showed that the content of Chlorophyll, ACC, RUBP and PEP in the LD was apparently higher than that in control group(high density, HD). While the content of PPO and AO in the LD was noticeably lower than that in the HD. There were 3808 differentially expressed genes (DEGs) were detected between HD and LD, of which 1935, 2390 and 1108 DEGs were found in the three comparisons(middle-upper, lower-outer and lower-inner), respectively. 274 common differentially expressed genes (co-DEGs) were contained in all three comparisons. Functional enrichment and KEGG pathway analysis found these genes were involved in Carbon fixation in photosynthetic organisms, Circadian rhythm, Photosynthesis - antenna proteins, Photosynthesis, chlorophyll metabolism, Porphyrin, sugar metabolism and so on. Among these genes, LHCB family participated in photosynthesis as parts of photosystem II. In addition, SPA1, rbcL, SNRK2, MYC2, BSK, SAUR and PP2C are involved in Circadian rhythm, the expression of genes related to glycometabolism and hormone signaling pathway is also changed. The results revealed that the decrease of plant density changed the photosynthetic efficiency of leaves and the expression of photosynthesis-related genes, which provide a theoretical basis for the actual production regulation of apples.