Cis-Regulation by NACs: A Promising Frontier in Wheat Crop Improvement

Abstract

Crop traits are controlled by multiple genes; however, the complex spatio-temporal transcriptional behavior of genes cannot be fully understood without comprehending the role of transcription factors (TFs) and the underlying mechanisms of the binding interactions of their cis-regulatory elements. NAC belongs to one of the largest families of plant-specific TFs and has been associated with the regulation of many traits. This review provides insight into the cis-regulation of genes by wheat NACs (TaNACs) for the improvement in yield-related traits, including phytohormonal homeostasis, leaf senescence, seed traits improvement, root modulation, and biotic and abiotic stresses in wheat and other cereals. We also discussed the current potential, knowledge gaps, and prospects of TaNACs.

High- or Low-Yielding F2 Progeny of Wheat Is Result of Specific TaCKX Gene Coexpression Patterns in Association with Grain Yield in Paternal Parent

“…As reviewed in the introduction, any deviations from the non-Mendelian inheritance of a parent-of-origin expression pattern might be the effect of epigenetic regulation. The main factors of this epigenetic regulation are the balance of gene dosage [ 28 ], small interfering RNAs [ 36 , 41 ], noncoding RNAs [ 44 , 45 ], or cis - and/or trans -regulatory elements [ 34 , 35 , 36 , 37 , 38 ]. All of them might be involved in the regulation of these epigenetic types of expression patterns, especially in polyploid species.…”

“…This gene is specifically or not specifically correlated with others expressed in the spikes or spikes per roots TaCKX GFMs of all crosses and showed negative regression with grain yield and root mass, coupling positively or negatively with other TaCKX GFMs. The TaNAC2-5A belongs to the large family of NAC genes, which encode NAC-type transcription factors that are involved in the regulation of important agronomic traits [ 26 , 38 , 63 , 64 ]. The overexpression of the TaNAC2-5A enhanced root growth and increased the ability of the root to acquire nitrogen and, under field conditions, increased nitrate uptake and grain yield [ 26 ].…”

“…Such nonadditive gene expression levels associated with phenotypic heterosis in F 1 plants have already been reported and reviewed [ 29 , 30 , 31 , 32 , 33 ]. These deviations from the general role are the result of different factors, such as epigenetic regulation by transcription factors [ 34 , 35 , 36 , 37 , 38 ], the balance of gene dosage [ 39 , 40 ], small interfering RNAs (sRNA) [ 36 , 41 ], histone modifications [ 42 ], R-loop formation [ 43 ], or distally acting factors [ 31 ]. Furthermore, noncoding RNAs have been described as regulators of the development of shoots and grains in barley [ 44 ] and dominant epigenetic regulators of early meiotic stages in wheat, ensuring reproductive success [ 45 ].…”

Functions of Plant Phytochrome Signaling Pathways in Adaptation to Diverse Stresses

“…HEMERA is a key regulating factor in phyB-mediated photomorphogenesis, which interacts with PIF4, inducing thermomorphogenesis associated gene expression and PIF4 accumulation, and participating in the thermomorphogenesis of plants [121]. PIF4 can directly interact with the promoters of NAC019 (NAC Domain Containing Protein 019) and IAA29 (Indole-3-Acetic Acid Inducible 29); therefore, PIF4/5 can activate SAG113 (Senescence-associated Gene 29) and NAC019, while repressing IAA29 and CBF2 expression to complete the regulation of leaf senescence under high-temperature stress in Arabidopsis [122,123]. Under high temperatures (28 • C), TCP17 bind directly to the promoter of PIF4 and promote its transcription [124].…”

“…PIF4 abundantly expressed to initiate a protective pathway in plants under high temperature [81,117,118]. PIF4 Regulate the expression of NAC019, IAA29, SAG113, NAC019, CBF2, TCP17 and HsfA2 [30,81,117,118,123,124]. Under high temperature, plants rapidly accumulate PIF7, inducing transcription of YUC8/9, IAA19/29 to initiate the thermomorphogenesis [118,126].…”