Nanobiotechnology has garnered attention in recent years as a means of alleviating the limits imposed by abiotic stressors. Zinc is an important micronutrient for plants since it aids in the production of numerous macromolecules. Wheat is regarded as the world's second most important food crop. Until 2050, wheat crop growth yield must be increased by 60% to meet humanity's nutritional needs but wheat productivity is declining due to different biotic and abiotic stresses. Out of all abiotic stresses, salinity and drought are two major stresses hindering wheat productivity. Keeping the above facts in mind present investigation was aimed to study the mitigation of salinity and drought in wheat using zinc oxide nanoparticles (ZnO NP). Seeds of wheat varieties HD 2009 & KRL 210 were soaked in 500 ppm ZnO NP solution for 12Hrs then were grown hydroponically in saline, PEG & a combination of two solution keepimg water as the control for 20 days. Different morphological and biochemical traits and proteomic responses were studied and it ZnO NP were found effective in both the verities, HD 2009 and KRL 210 but trait response was different. The response of HD 2009 was better for traits shoot length, shoot fresh weight, root dry weight, shoot dry weight, root and shoot RWC, total chlorophyll content, shoot proline content, root and shoot FRSA and KRL 210 responded better for germination percentage, root length, root fresh weight, root and shoot MSI, root and shoot MDA content, root proline content, root and shoot content H2O2 content. Protein profiling analysis salinity (6 dSm-1 & 10 dSm-1) with and without ZnO NP revealed that 90 proteins were differentially expressed under 6 dSm-1 % under salinity (10 dSm-1) 45 proteins were differentially expressed. The mitigating effect of zinc oxide nanoparticles at the seedling stage could be due to the expression of proteins related to the antioxidant defense system (Peroxidase and Superoxidase dismutase), amino acid metabolism, ribosomal protein, photosynthesis, carbohydrate metabolism, ubiquitination, glycolysis, and tricarboxylic acid cycle revealed in proteomics study. Based on the above experiment it is concluded that 500 ppm of zinc oxide nanoparticles for 12 hrs soaking is effective in mitigating salinity and drought. Traits like germination percentage, seedling growth parameters, seedling vigor index-primary determints of growth under stress conditions get positively affected by nanopariming of zinc oxide in this experiment and can be used for its application in field. 

Xm-50404

Difference analysis of miRNA regulation in drought response of photosynthetic system in different wheat varieries

Ruixiang Zhou1, Menghan Zhang1, Xinyu Xue1, Yuhang Song1, Yan Li2, Yongxia Wang2, Yuexia Wang1

1College of Life Sciences, Henan Agricultural University, Zhengzhou 450046, Henan, China

2Institute of Crops Molecular Breeding, Henan Academy of Agricultural Sciences, Zhengzhou 450002, Henan, China

Flag leaves photosynthetic strength is essential for grain fullness and yield. And water deficiency during the grain filling stage of wheat will directly affect its yield. MicroRNAs (miRNAs), as an endogenous non-coding RNAs, play key roles in regulating flag leaf photosynthetic of during the grain filling stage in wheat.

In this study, a new high-yielding cultivar Zhengmai 1860, a high-yielding cultivar Bainong 207 and Zhoumai 18 were used to explore the ultrastructure of flag leaf chloroplasts of wheat flag leaves from different cultivars at the grain filling stage, key enzymes involved in photosynthesis and photosynthetic products. Transcriptome sequencing was used to analyze the expression differences of miRNAs and mRNAs to construct a relevant network of physiologically relevant miRNA-mRNA regulation of wheat flag leaf photosynthesis. The main results are as follows:

1. The gas exchange parameters and chlorophyll-a fluorescence parameters of Zhengmai 1860 were significantly higher than those of Bainong 207 and Zhoumai 18 at early and mid-grain filling stages, and they maintained higher ATPase activity and NADPH enzyme content. The results of chlorophyll content and SPAD value of flag leaves in this period showed that those of Zhengmai 1860 was slightly higher than those of Bainong 207, and significantly higher than those of Zhoumai 18.

2. The flag leaf sucrose and starch contents were also higher at early grain filling stage in Zhengmai 1860, but were significantly lower at mid filling stage compared with the other cultivars. Transmission electron microscopy observed that the flag leaf had more obvious and full starch grains at early filling stage, but disappeared at the mid-stage. The chloroplast ultrastructure revealed that Zhengmai 1860 could maintain a relatively stable photosynthetic structure at mid grain filling stage.

3. In Zhengmai 1860, KEGG pathway enrichment analysis found that 2 of the target genes were invovled in the alpha-Linolenic acid metabolism. Bioinformatics analysis showed that the functions of them were coding genes for allene oxide synthase (AOS).

Our results showed that under drought stress during the grain filling stage, zhengmai 1860 could maintain an intact photosynthetic structure and had a higher absorption and transformation capacity for light energy during the mid-grain filling stage, transport the photosynthetic products from the flag leaf more rapidly to the grain, maintain a higher photosynthetic rate, and thus accumulate more sucrose with starch to improve grain yield. The flag leaf of Zhengmai 1860 influenced AOS encoding gene expression by regulating tae-mirna408 expression, which in turn modulated the contents of jasmonate hormones and ABA and delayed the senescence of the flag leaf of Zhengmai 1860, thereby transporting more photosynthetic products to the grain.