Increased attention on the agricultural impacts to environment has revealed excessive N input to be a major concern. Sowing date reportedly impacts crop N uptake, however, few studies have assessed the effects of late sowing with reduced N apply on crop N status and grain yield. We evaluated three treatments: normal sowing (8 October), late sowing (22 October), and optimized late sowing (22 October, with 75% N application) over two wheat (Triticum aestivum L.) growing seasons (2017)(2018)(2019), and assessed their effects on crop N status, N allocation and use, net photosynthetic rate (P max ), grain yield, and soil N budget. Compared to normal sowing, optimized late sowing resulted in near-optimum N status, improved nitrogen use efficiency (NUE), nitrogen utilization efficiency (UTE), and nitrogen uptake efficiency (UPE), while maintaining a high yield. Although aboveground N uptake of late and optimized late sowing at anthesis was lower than that of normal sowing, N distribution was more optimized, mainly manifesting as: unchanged N allocation to the individual plant, but increased N allocation to flag leaf, and steeper green leaf area N in the canopy under optimized late sowing. Optimized N nutrition index and N distribution under late sowing contributed to a higher P max , which resulted in a higher dry matter accumulation rate during post-anthesis, and ultimately a consistent grain yield among the three treatments. Moreover, N input reduction under optimized late sowing decreased the final mineral N in the 0-100-cm soil layer at harvest and apparent N loss, which reduced environmental pollution and resources waste.Abbreviations: AGN, aboveground nitrogen uptake; N f-min , final mineral N in the 0-100-cm soil layer at harvest; N loss , apparent N loss; NNI, nitrogen nutrition index; NUE, nitrogen use efficiency; P max , net photosynthetic rate; SLN, specific green leaf area nitrogen; UPE, nitrogen uptake efficiency; UTE, nitrogen utilization efficiency.

Wheat (Triticum aestivum L.), the most widely cultivated crop, is affected by waterlogging that limited the wheat production. Given the incompleteness of its genome annotation, PacBio SMRT plus Illumina short-read sequencing strategy provided an efficient approach to investigate the genetic regulation of waterlogging stress in wheat. A total of 947,505 full-length non-chimetric (FLNC) sequences were obtained with two wheat cultivars (XM55 and YM158) with PacBio sequencing. Of these, 5,309 long-non-coding RNAs, 1,574 fusion genes and 739 transcription factors were identified with the FLNC sequences. These full-length transcripts were derived from 49,368 genes, including 47.28% of the genes annotated in IWGSC RefSeq v1.0 and 40.86% genes encoded two or more isoforms, while 27.31% genes in the genome annotation of IWGSC RefSeq v1.0 were multiple-exon genes encoding two or more isoforms. Meanwhile, the individuals with waterlogging treatments (WL) and control group (CK) were selected for Illumina sequencing. Totally, 6,829 differentially expressed genes (DEGs) were detected from four pairwise comparisons. Notably, 942 DEGs were overlapped in the two comparisons (i.e., XM55-WL vs. YM158-WL and YM158-WL vs. YM158-CK). Undoubtedly, the genes involved in photosynthesis were downregulated after waterlogging treatment in two cultivars. Notably, the genes related to steroid biosynthesis, steroid hormone biosynthesis, and downstream plant hormone signal transduction were significantly upregulated after the waterlogging treatment, and the YM158 variety revealed different genetic regulation patterns compared with XM55. The findings provided valuable insights into unveiling regulation mechanisms of waterlogging stress in wheat at anthesis and contributed to molecular selective breeding of new wheat cultivars in future.

Background Waterlogging is one of the major abiotic stresses limiting wheat product. Plants can adapt to waterlogging with changes in morphology, anatomy, and metabolism. A number of genes or proteins were responsive to waterlogging. Results in this sduty, the iTRAQ-based proteomic strategy was applied to identify waterlogging-responsive proteins in wheat. A total of 7710 proteins were identified in waterlogging tolerant and sensitive wheat varieties XM55 and YM158 at anthesis under waterlogging or not. Sixteen proteins were differentially accumulated between XM55 and YM158 under waterlogging with cultivar specificity. Among them, eleven proteins were up-regulated and five proteins were down-regulated. The up-regulated proteins included Fe-S cluster assembly factor, heat shock cognate 70, GTP-binding protein SAR1A-like, and CBS domain-containing protein. The down-regulated proteins contained photosystem II reaction center protein H, carotenoid 9,10 (9',10')-cleavage dioxygenase-like, psbP-like protein 1, and mitochondrial ATPase inhibitor. In addition, nine proteins were responsive to waterlogging with non-cultivar specificity. These proteins included 3-isopropylmalate dehydratase large subunit, solanesyl-diphosphate synthase 2, DEAD-box ATP-dependent RNA helicase 3, and three predicted or uncharacterized proteins. Sixteen out of the twenty-eight selected proteins showed consistent expression patterns between mRNA and protein levels by quantitative real-time PCR. Conclusions: Our study indicates the much proteins were differential accumulated between the two contrast waterlogging wheat varieties in response to waterlogging, which provide insight into wheat response to waterlogging stress. The identified differentially accumulated protein might be applied to develop waterlogging tolerant wheat.

Background : Waterlogging is one of the major abiotic stresses limiting wheat product. Plants can adapt to waterlogging with changes in morphology, anatomy, and metabolism. Many genes and proteins play critical roles in adaptation to waterlogging. Results : in this study, the iTRAQ-based proteomic strategy was applied to identify the waterlogging-responsive proteins in wheat. A total of 7,710 proteins were identified in two wheat varieties, XM55 (waterlogging-tolerant) and YM158 (waterlogging-sensitive), at anthesis under waterlogging or not. Sixteen proteins were differentially accumulated between XM55 and YM158 under waterlogging with cultivar specificity. Of these, 11 proteins were up-regulated and 5 proteins were down-regulated. The up-regulated proteins included Fe-S cluster assembly factor, heat shock cognate 70, GTP-binding protein SAR1A-like, and CBS domain-containing protein. The down-regulated proteins contained photosystem II reaction center protein H, carotenoid 9,10 (9',10')-cleavage dioxygenase-like, psbP-like protein 1, and mitochondrial ATPase inhibitor. In addition, 9 proteins were responsive to waterlogging with non-cultivar specificity. These proteins included 3-isopropylmalate dehydratase large subunit, solanesyl-diphosphate synthase 2, DEAD-box ATP-dependent RNA helicase 3, and 3 predicted or uncharacterized proteins. Sixteen out of the 28 selected proteins showed consistent expression patterns between mRNA and protein levels. Conclusion s: This study revealed that the proteins were differential accumulated between the two contrast waterlogging wheat varieties in response to waterlogging, which provide valuable insights into wheat response to waterlogging stress. The identified differentially accumulated protein might be applied to develop waterlogging tolerant wheat.

Background: Waterlogging is one of the major abiotic stresses limiting wheat product. Plants can adapt to waterlogging with changes in morphology, anatomy, and metabolism. Many genes and proteins play critical roles in adaptation to waterlogging. Results: the iTRAQ-based proteomic strategy was applied to identify the waterlogging-responsive proteins in wheat. A total of 4,999 unique proteins were identified in two wheat varieties, XM55 (waterlogging-tolerant) and YM158 (waterlogging-sensitive), at anthesis under waterlogging or not. Sixteen proteins were differentially accumulated between XM55 and YM158 under waterlogging with cultivar specificity. Of these, 11 proteins were up-regulated and 5 proteins were down-regulated. The up-regulated proteins included Fe-S cluster assembly factor, heat shock cognate 70, GTP-binding protein SAR1A-like, and CBS domain-containing protein. The down-regulated proteins contained photosystem II reaction center protein H, carotenoid 9,10 (9',10')-cleavage dioxygenase-like, psbP-like protein 1, and mitochondrial ATPase inhibitor. In addition, 9 proteins were responsive to waterlogging with non-cultivar specificity. These proteins included 3-isopropylmalate dehydratase large subunit, solanesyl-diphosphate synthase 2, DEAD-box ATP-dependent RNA helicase 3, and 3 predicted or uncharacterized proteins. Conclusions: This study revealed that the proteins were differential accumulated between the two contrast waterlogging wheat varieties in response to waterlogging, which provide valuable insights into wheat response to waterlogging stress. These differentially accumulated proteins might be applied to develop waterlogging tolerant wheat in further breeding programs.