The Involvement of the Banana F-Box Protein MaEBF1 in Regulating Chilling-Inhibited Starch Degradation through Interaction with a MaNAC67-Like Protein

Abstract

Low-temperature storage is a common strategy for preserving and transporting vegetables and fruits. However, many fruits are hypersensitive to chilling injury, including bananas. In the present study, storage conditions of 11 °C delayed the ripening of Fenjiao (Musa ABB Pisang Awak) banana, and the pulp could be softened after ethephon treatment. Storage conditions of 7 °C prevented fruit from fully softening, and fruit contained a significantly higher starch content and lower soluble sugar content. MaEBF1, a critical gene component in the ethylene signaling pathway, was repressed during ripening after fruit had been stored for 12 days at 7 °C. The expression of a series of starch degradation-related genes and a MaNAC67-like gene were also severely repressed. Both MaEBF1 and MaNAC67-like genes were ethylene-inducible and localized in the nucleus. MaNAC67-like protein was able to physically bind to the promoter of genes associated with starch degradation, including MaBAM6, MaSEX4, and MaMEX1. Yeast two-hybrid, GST-pull down, and BiFC assays showed that MaEBF1 interacted with the MaNAC67-like protein, and their interaction further activated the promoters of MaBAM6 and MaSEX4. The current study indicates that MaNAC67-like is a direct regulator of starch degradation and potential for involvement in regulating chilling-inhibited starch degradation by interacting with the ethylene signaling components in banana fruit. The present work paves the way for further functional analysis of MaEBF1 and MaNAC67-like in banana, which will be useful for understanding the regulation of banana starch metabolism and fruit ripening.

A chromosome‐level genome assembly provides insights into ascorbic acid accumulation and fruit softening in guava (Psidium guajava)

“…The abundance of volatile metabolites in mature and soft guava fruit (Moon et al ., 2018) may depend on the hydrolysis of starch, which protects cell membranes and maintains firmness. Starch degradation was also reported as playing a key role in fruit softening in banana (Musaceae) (Shiga et al ., 2011; Song et al ., 2019) and persimmon (Ebenaceae) (Jung et al ., 2017). The reference genome of guava reported here will facilitate studies on both ripening and softening mechanisms and support efforts to prolong the shelf life of guava fruits.…”

NAC Transcription Factor Family Regulation of Fruit Ripening and Quality: A Review

“…Moreover, MaNAC67-like could interact with ethylene signal transduction TF MaEBF1 to further enhance the capacity for transcriptional activation to MaBAM6 and MaSEX4. These results suggest that the inhibition of expression of MaNAC67-like and its interacting proteins is one of the main ways that low temperature inhibits banana fruit ripening [136].…”

A banana transcriptional repressor MaAP2a participates in fruit starch degradation during postharvest ripening

“…Starch degradation of banana fruit is a meaningful and fateful biological process comprising multiple important enzymatic activities (Supplemental Table S2), such as GWD, PWD, BAM, and AMY, and increasing proofs reveal that ripening-related TFs build an intricate regulatory network to modulate changes of starch (Xiao et al, 2018;Song et al, 2019;Miao et al, 2020;Jiang et al, 2021;Liu et al, 2021;Zhu et al, 2021). Based on the well-defined role of GWD in the initiation of leaf temporary starch degradation, banana MaGWD1 that was consistent with fruit ripening also played a great job in starch degradation (Xiao et al, 2018).…”

“…In the promoters of key functional genes associating with fruit ripening, there are abundant specific DNA sequence motifs for interaction with corresponding TFs, which provide the essential regulation chances for TFs during the developmental processes. A recent study successively found that MaEIL2, MaMYB16L, MaARF2/12/24, MaMYB3/308, and MaMADS36/55 took part in the regulation of banana fruit starch degradation (Song et al, 2019;Miao et al, 2020;Jiang et al, 2021;Liu et al, 2021;Zhu et al, 2021). Thus, it can be seen that the starch degradation process in starchy banana fruits during ripening is complex and regulated multidimensionally.…”