The NAC transcription factor FaRIF controls fruit ripening in strawberry

Abstract

In contrast to climacteric fruits such as tomato, the knowledge on key regulatory genes controlling the ripening of strawberry, a non-climacteric fruit, is still limited. NAC transcription factors mediate different developmental processes in plants. Here, we identified and characterized FaRIF (Ripening Inducing Factor), a NAC transcription factor that is highly expressed and induced in strawberry receptacles during ripening. Functional analyses based on stable transgenic lines aimed at silencing FaRIF by RNA interference, either from a constitutive promoter or the ripe receptacle-specific EXP2 promoter, as well as overexpression lines showed that FaRIF controls critical ripening-related processes such as fruit softening and pigment and sugar accumulation. Physiological, metabolome and transcriptome analyses of receptacles of FaRIF-silenced and overexpression lines point to FaRIF as a key regulator of strawberry fruit ripening from early developmental stages, controlling abscisic acid (ABA) biosynthesis and signaling, cell wall degradation and modification, the phenylpropanoid pathway, volatiles production, and the balance of the aerobic/anaerobic metabolism. FaRIF is therefore a target to be modified/edited to control the quality of strawberry fruits.

Autophagy Is Required for Strawberry Fruit Ripening

“…Our analysis of the ATG8 lipidation, which is a critical step in the autophagy progress, points to two time points during ripening of highest ATG8 content and lipidation: during the white stage and at the end of ripening in a pre-senescent stage. Growth of strawberry fruit, as in other fleshy fruits, is supported by fruit metabolism that must be energetically adjusted during the transition from green to ripe stage (Carrari and Fernie, 2006;Fait et al, 2008;Jing and Malladi, 2020;Martín-Pizarro et al, 2021). In this process, there is a critical step when the limited photosynthetic capacity of the green fruit is completely lost after the loss of chlorophyll.…”

MicroRNAs and Transcripts Associated with an Early Ripening Mutant of Pomelo (Citrus grandis Osbeck)

“…Members of NAC family are involved in the regulation of ripening-associated processes in fruits, such as citrus [68], apple [69] and strawberry [70,71]. In cucumber, 12 NAC genes were found to target 13 known miRNAs which were involved in fruit spine development [72].…”

A Method for Assaying of Protein Kinase Activity In Vivo and Its Use in Studies of Signal Transduction in Strawberry Fruit Ripening

“…In recent years, studies of the molecular mechanisms involved in fruit ripening have focus on the structural genes that function in the regulation of physiological and biochemical metabolic pathways [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], and there is relatively little information regarding the underlying signaling mechanisms. One obstacle to the elucidation of fruit ripening-associated signal transduction has been the absence of appropriate in vivo protein kinase activity assays.…”

“…is an established experimental model for the study of fleshy fruit ripening, a complex process that involves substantial changes in numerous physiological and metabolic pathways. While many early studies of fruit ripening largely focused on the physiological and biochemical processes [ 1 , 2 , 3 ], more recent studies have targeted the underlying molecular mechanisms [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Such analyses have examined the roles of both structural and regulatory genes: the former encode proteins that directly control physiological and biochemical processes, and the latter act to control the behavior of the functional genes/proteins, and as such, make up complex signaling networks.…”