Characterization of Starch Degradation Related Genes in Postharvest Kiwifruit

Abstract

Starch is one of the most important storage carbohydrates in plants. Kiwifruit typically accumulate large amounts of starch during development. The fruit retain starch until commercial maturity, and its postharvest degradation is essential for consumer acceptance. The activity of genes related to starch degradation has, however, rarely been investigated. Based on the kiwifruit genome sequence and previously reported starch degradation-related genes, 17 novel genes were isolated and the relationship between their expression and starch degradation was examined using two sets of materials: ethylene-treated (100 µL/L, 20 °C; ETH) vs. control (20 °C; CK) and controlled atmosphere stored (CA, 5% CO2 + 2% O2, 0 °C) vs. normal atmosphere in cold storage (NA, 0 °C). Physiological analysis indicated that ETH accelerated starch degradation and increased soluble solids content (SSC) and soluble sugars (glucose, fructose and sucrose), while CA inhibited starch reduction compared with NA. Using these materials, expression patterns of 24 genes that may contribute to starch degradation (seven previously reported and 17 newly isolated) were analyzed. Among the 24 genes, AdAMY1, AdAGL3 and AdBAM3.1/3L/9 were significantly induced by ETH and positively correlated with starch degradation. Furthermore, these five genes were also inhibited by CA, conforming the likely involvement of these genes in starch degradation. Thus, the present study has identified the genes with potential for involvement in starch degradation in postharvest kiwifruit, which will be useful for understanding the regulation of kiwifruit starch content and metabolism.

Genome‐wide analysis of coding and non‐coding RNA reveals a conserved miR164‐NAC regulatory pathway for fruit ripening

“…To understand the molecular mechanisms of kiwifruit ripening, biosynthetic genes and transcription factors have been identified, after manipulation of ethylene production (Atkinson et al, 2011), cell wall metabolism (Atkinson et al, 2009), starch degradation (Hu et al, 2016;Zhang et al, 2018a) and aroma formation (Nieuwenhuizen et al, 2015). To understand the molecular mechanisms of kiwifruit ripening, biosynthetic genes and transcription factors have been identified, after manipulation of ethylene production (Atkinson et al, 2011), cell wall metabolism (Atkinson et al, 2009), starch degradation (Hu et al, 2016;Zhang et al, 2018a) and aroma formation (Nieuwenhuizen et al, 2015).…”

“…Kiwifruit is an ideal species to understand fruit ripening, as it is considered a typical climacteric fruit and also is more sensitive to ethylene than most other fruit. To understand the molecular mechanisms of kiwifruit ripening, biosynthetic genes and transcription factors have been identified, after manipulation of ethylene production (Atkinson et al, 2011), cell wall metabolism (Atkinson et al, 2009), starch degradation (Hu et al, 2016;Zhang et al, 2018a) and aroma formation (Nieuwenhuizen et al, 2015). Here, the regulatory roles of micro (mi)RNAs for kiwifruit ripening were studied via analysis of the sRNAome, degradome and transcriptome.…”

A banana R2R3‐MYB transcription factor MaMYB3 is involved in fruit ripening through modulation of starch degradation by repressing starch degradation‐related genes and MabHLH6

“…In addition, several MYB TFs like FaMYB10 and FaEOBII, mediate the production of volatile compounds by targeting phenylpropanoid pathway genes during strawberry fruit ripening (Medina‐Puche et al ., , ). Similarly, in apple MdMYB1/10/73 modulate fruit organic acid accumulation by directly activating vacuolar transporters (Hu et al ., ,b, ). However, the involvement of MYB TFs in complex carbohydrate metabolism associated with fruit quality during ripening has not been well understood.…”

“…In addition, maltose excess protein (MEX1) and plastidic glucose transporter (pGlcT) transfer maltose and glucose to cytosol (Cho et al ., ). Many genes encoding these starch degradation enzymes have been isolated in kiwifruit (Hu et al ., ,b) and bananas (Gao et al ., ; Xiao et al ., ). Moreover, it has been shown that starch degradation in these fruits is highly complex and is mediated by the changes of starch degradation enzymes at transcript and protein levels (Gao et al ., ; Hu et al ., ,b; Xiao et al ., ).…”

“…Many genes encoding these starch degradation enzymes have been isolated in kiwifruit (Hu et al ., ,b) and bananas (Gao et al ., ; Xiao et al ., ). Moreover, it has been shown that starch degradation in these fruits is highly complex and is mediated by the changes of starch degradation enzymes at transcript and protein levels (Gao et al ., ; Hu et al ., ,b; Xiao et al ., ). We recently identified a bHLH TF MabHLH6 in banana fruit that acts as a positive modulator of starch degradation by directly targeting the promoters of 11 starch degradation‐related genes (Xiao et al ., ).…”