Miao, M. | Search bioRxiv

bioRxiv2018

SlARF10, an auxin response factor, is required for chlorophyll and sugar accumulation during tomato fruit development

Tomato green fruits photosynthesis contributes to fruit growth and carbon economy. Tomato auxin response factor 10 (SlARF10) is one of the members of ARF family. Our results showed that SlARF10 locates in the nucleus and has no transcriptional activity. SlARF10 was expressed in various tomato tissues, but highly expressed in green fruit. Up-regulation of SlARF10 produced dark green phenotype of fruits, whereas down-regulation of SlARF10 had light green phenotype. Autofluorescence and chlorophyll content analysis confirmed the phenotypes, which indicated that SlARF10 plays an important role in chlorophyll accumulation in tomato fruits. Up-regulation of SlARF10 increased the photochemical potential in tomato leaves and fruits. Furthermore, the SlARF10 up-regulating lines displayed improved accumulation of starch in fruits, whereas SlARF10 suppressed lines had inhibited starch accumulation. Up-regulation of SlARF10 increased the expression of AGPases, the starch biosynthesis genes. SlARF10 up-regulating lines had increased accumulation of SlGLK1 and SlGLK2 transcripts in fruits. The promoter sequence of SlGLK1 gene had two conserved ARF binding sites. SlARF10 may regulate the expression of SlGLK1, thus controlling chlorophyll accumulation, photosynthesis rates and sugars synthesis in fruits. Our study provided more insight on the link between auxin signaling, chloroplastic activity and sugar metabolism during the development of tomato fruits.\n\nAbbreviations\n\nHighlightSlARF10 played an important role in the chlorophyll accumulation and photosynthesis in tomato fruits. SlARF10 was involved in starch accumulation by controlling the expression of starch synthesis related enzyme genes. SlARF10 may regulate the expression of SlGLK1, thus controlling chlorophyll accumulation, photosynthesis rates and sugars synthesis in tomato fruits.

plant biology↗

bioRxiv2017

Metabolic process of raffinose family oligosacharrides during cold stress and recovery in cucumber leaves

Raffinose family oligosacharrides (RFOs) accumulate under stress conditions in many plants and have been suggested to act as stress protectants. To elucidate the metabolic process of RFOs under cold stress, levels of RFOs and relative carbohydrates, the expression and activities of main metabolic enzymes and their subcellular compartments were investigated during low temperature treatment and recovery period in cucumber leaves. Cold stress induced the accumulation of stachyose in vacuoles, galactinol in vacuoles and cytosols, and sucrose and raffinose in vacuoles, cytosols and chloroplasts. After cold stress removal, levels of these sugars decreased gradually in respective compartments. Among 4 galactinol synthase genes (CsGS), CsGS1 was not affected by the cold stress, while other three CsGSs were up-regulated by the low temperature. RNA levels of acid--galactosidase (GAL) 3, alkaline--galactosidase (AGA) 2 and 3, and the activities of GAL and AGA were up-regulated after cold stress removal. The GAL3 protein and GAL activity were exclusively located in the vacuole, whereas the protein of AGA2 and AGA 3 were found in the cytosol and chloroplast respectively. The results indicate that RFOs accumulated during the cold stress in different subcellular compartments in cucumber leaves could be catabolized in situ by different galactosidases after stress removal.

plant biology↗