Induction of jasmonate signalling regulators MaMYC2s and their physical interactions with MaICE1 in methyl jasmonate‐induced chilling tolerance in banana fruit

Abstract

MYC2, a basic helix-loop-helix (bHLH) transcription factor, is a key regulator in the activation of jasmonate (JA) response. However, the molecular details of MYC2 involving in methyl jasmonate (MeJA)-induced chilling tolerance of fruit remain largely unclear. In the present work, two MYC2 genes, MaMYC2a and MaMYC2b, and one homolog of the inducer of the C-repeat-binding factor (CBF) gene, MaICE1 were isolated and characterized from banana fruit. MaMYC2s and MaICE1 were found to be all localized in the nucleus. In addition, the proline-rich domain (PRD) and the acidic domain (AD) in the N-terminus were important for the transcriptional activation of MaMYC2 in yeast cells. Unlike MaICE1's constitutive expression, MaMYC2a and MaMYC2b were induced rapidly following MeJA treatment during cold storage. Moreover, protein-protein interaction analysis confirmed that MaMYC2s interacted with MaICE1. The expression of ICE-CBF cold-responsive pathway genes including MaCBF1, MaCBF2, MaCOR1, MaKIN2, MaRD2 and MaRD5 was also significantly induced by MeJA. Taken together, our work provides strong evidence that MaMYC2 is involved in MeJA-induced chilling tolerance in banana fruit through physically interacting and likely functionally coordinating with MaICE1, revealing a novel mechanism for ICE1 in response to cold stress as well as during development of induced chilling tolerance.

Using jasmonates and salicylates to reduce losses within the fruit supply chain

“…Overall visual quality was also improved in strawberries treated with MeJA at 100 µmol l -1 , stored at 7.5 °C [22] or treated with SA at 2000 µmol l -1 [35], in banana dipped in MeJA at 100 µmol l -1 for 30 min, subsequently stored at 7 °C [96], in grapefruit dipped in JA at 10 and 50 µmol l -1 for 30 s, stored at 2 °C plus shelf-life at 20 °C [19], in tomatoes treated with MeSA or MeJA at 10 µmol l -1 for 16 h, stored at 5 °C plus shelf-life at 20 °C [76] or treated with MeSA at 100 µmol l -1 [105], and bell peppers treated with MeJA and MeSA at 100 µmol l -1 , stored at 0 °C [106]. The majority of these positive responses were associated with the ability of jasmonates and salicylates to prevent chilling injury and/or decay in the produce, which is a welldocumented phenomenon of these compounds [49,56,95,97,107].…”

“…Other authors found reduced skin browning in pomegranates treated with ASA at 100, 500 and 1000 µmol l -1 for 10 min [13] or treated with MeJA or MeSA at 10 and 100 µmol l -1 for 16 h [12] stored at 2 °C, and in banana treated with MeJA at 100 µmol l -1 for 30 min, stored at 7 °C [96], these changes were associated with reduced chilling injury.…”

“…in loquat treated with MeJA at 10 µmol l -1 for 24 h, stored at 1 °C [11], mangos treated with MeJA at 100 µmol l -1 for 24 h, stored at 7 °C plus shelf-life at 20 °C [26], pomegranates treated with MeJA and MeSA at 10 and 100 µmol l -1 for 16 h, stored at 2 °C plus shelf-life at 20 °C [12], Qingnai plums treated with SA at 1500 µmol l -1 for 10 min, stored at 1 °C plus shelf-life at 20 °C [24], and tomatoes treated with MeSA at 50 µmol l -1 for 12 h, stored at 2 °C [14]. The mechanisms involved are related to changes in the content of polyamines [14,24,60,34,95] and proline [10,95,96], cell wall modification [11], the energy status [56,60] and changes in the membrane fatty acid composition [16,97].…”

“…pitting and sunken lesions on the peel [26,27,96], discoloration associated with ripening, changes in pigments content [29,40,104], and/or due to external and internal tissue browning [12,13,44].…”

“…in banana treated with MeJA at 100 µmol l -1 for 30 min, stored at 7 °C [96], in loquat treated with MeJA at 10 µmol l -1 for 24 h, stored at 1 °C [10], and tomatoes treated with MeJA at 50 µmol l -1 for 12 h, stored at 2 °C [95] was also associated with increased content of proline, which is involved in osmotic regulation, preventing cells from dehydration and improving turgor maintenance during storage, supporting the role of PAs.…”