Although studies have shown the concomitant occurrence of autophagic and programmed cell death (PCD) in plants, the relationship between autophagy and PCD and the factors determining this relationship remain unclear. In this study, seedlings of the wheat cultivar Jimai 22 were used to examine the occurrence of autophagy and PCD during polyethylene glycol (PEG)-8000-induced drought stress. Autophagy and PCD occurred sequentially, with autophagy at a relatively early stage and PCD at a much later stage. These findings suggest that the duration of drought stress determines the occurrence of PCD following autophagy. Furthermore, the addition of 3-methyladenine (3-MA, an autophagy inhibitor) and the knockdown of autophagy-related gene 6 (ATG6) accelerated PEG-8000-induced PCD, respectively, suggesting that inhibition of autophagy also results in PCD under drought stress. Overall, these findings confirm that wheat seedlings undergo autophagic survival under mild drought stress, with subsequent PCD only under severe drought.

Fusarium head blight (FHB) is a major devastating wheat fungal disease. Mycotoxins act as virulent factor for FHB progression, including deoxynivalenol (DON), 15-acetyl deoxynivalenol (15-ADON), 3-acetyl deoxynivalenol (3-ADON), deoxynivalenol-3-glucoside (D3G), and zearalenone (ZEN). To identify resistant germplasm against FHB and mycotoxin accumulation, we evaluated 99 wheat cultivars for FHB severity using point inoculation by three FHB isolates under greenhouse and field conditions. FHB severity of selected varieties evaluated in the fields were correlated with that in greenhouse (p < 0.01). Inoculated spikes from 20 varieties were examined for mycotoxin accumulation, employing an LC-MS/MS method that differentiated five mycotoxins. Five cultivars exhibited resistance to both FHB and mycotoxin accumulation, with FHB severity averaging from 13.36% to 33.37%, and DON accumulation below 2400.0 µg/kg, across various conditions. Seven dominant varieties exhibited moderate resistance to FHB and mycotoxin accumulation. FHB severity was significantly positively correlated with DON accumulation, but negatively correlated to the D3G to DON ratio, across distinct groups of FHB resistance (p < 0.01) after inoculation of three distinct isolates, although no correlation was observed within-group. In the present study, Shannong20, Huaimai20, and Sunlin were identified with resistance to both FHB and mycotoxins with superior agronomic performance, providing promising materials for improving disease resistance in breeding programs.

Pumilio (Pum)-family proteins are evolutionarily conserved RNA-binding proteins that regulate post-transcriptional processes; however, their specific functions in staple crops, for example, wheat (Triticum aestivum), remain poorly understood. We identified 56 TaPum genes and classified them into three phylogenetic subgroups (I–III). The larger TaPum family size in allohexaploid wheat was associated with retention of A-, B-, and D-subgenome homoeologs, segmental duplication, and tandem duplication. After separating homoeologous pairs, 17 segmental duplication pairs and five tandem duplication pairs were identified, and ratios of nonsynonymous to synonymous substitutions (Ka/Ks) below 1 were consistent with purifying selection. Subgroup-specific motifs and the uneven distribution of cis-acting elements, particularly abscisic acid (ABA)- and methyl jasmonate (MeJA)-responsive elements, suggested potential divergence in promoter regulatory architecture. Transcriptomic profiling and independent quantitative reverse transcription-polymerase chain reaction analysis showed more consistent response of TaPum genes to salt stress than to cold or drought stress. Salt stress strongly promoted TaPum-III-5b expression, and its encoded protein exhibited nuclear and cytoplasmic localization. Heterologous overexpression of TaPum-III-5b in Arabidopsis thaliana increased salt tolerance, as indicated by enhanced survival; augmented peroxidase, superoxide dismutase, and catalase activities; and diminished accumulation of reactive oxygen species and malondialdehyde. Electrophoretic mobility shift assay (EMSA) demonstrated sequence-specific binding of TaDREB2B to a dehydration-responsive element (DRE)-containing sequence in the TaPum-III-5b promoter, whereas dual-luciferase (Dual-LUC) analysis showed activation of the wild-type promoter. Together, these results support a proposed regulatory framework in which TaPum-III-5b may contribute to salt-stress responses through as-yet-unidentified downstream RNA targets. This study characterizes the Pum gene family in wheat and identifies the TaDREB2B-TaPum-III-5b module as a candidate regulatory pathway associated with salt-stress responses. Its potential application in wheat improvement requires further validation in wheat.