GIBBERELLIC ACID PRIMING ENHANCES MAIZE SEED GERMINATION UNDER LOW WATER POTENTIAL

<p class="abstrakinggris"><span lang="EN-US">Germination is a portentous yield determining factor that is a challenge in the low water potential environment due to disrupted imbibition. Hormonal seed priming can markedly increase the germination on maize even in such a stressful environment. Therefore, research was aimed to analyze the application of gibberellic acid (GA₃) priming to maize seeds to minimize the deleterious effects of reduced water potential. GA₃ priming was done at 0, 50, 100, 150, and 200 ppm for 12 hours and subjected to drought levels of 0, 0.15, 0.50, 1.05, and 1.75 MPa by using NaCl solution. Different germination parameters, i.e., germination percentage, mean germination time, germination index, relative water content, seedling vigor index, root length, and shoot length, were determined on the final day of the experiment. The results showed that all germination parameters were adversely influenced by low water potential. Every level of GA₃ priming has hastened all parameters. GA₃ priming at 100 ppm decreased the mean germination time by 35 hours under 1.75 MPa compared to non-primed seeds. GA₃ priming increased the shoot length of maize seedlings with a shoot length of 2.9 cm in non-primed seedlings compared to 6.4 cm in 200 ppm GA₃ priming under 1.05 MPa. GA₃ priming is the best method for the early establishment of maize seedlings in low water potential conditions. As a result, it may be utilized as a low-cost and straightforward approach for establishing maize crops under saline and drought conditions.</span></p>

Phosphoproteomics ofArabidopsisHighly ABA-Induced1 identifies AT-Hook–Like10 phosphorylation required for stress growth regulation

The clade A protein phosphatase 2C Highly ABA-Induced 1 (HAI1) plays an important role in stress signaling, yet little information is available on HAI1-regulated phosphoproteins. Quantitative phosphoproteomics identified phosphopeptides of increased abundance inhai1-2in unstressed plants and in plants exposed to low-water potential (drought) stress. The identity and localization of the phosphoproteins as well as enrichment of specific phosphorylation motifs indicated that these phosphorylation sites may be regulated directly by HAI1 or by HAI1-regulated kinases including mitogen-activated protein kinases, sucrose non-fermenting–related kinase 2, or casein kinases. One of the phosphosites putatively regulated by HAI1 was S313/S314 of AT-Hook–Like10 (AHL10), a DNA-binding protein of unclear function. HAI1 could directly dephosphorylate AHL10 in vitro, and the level ofHAI1expression affected the abundance of phosphorylated AHL10 in vivo. AHL10 S314 phosphorylation was critical for restriction of plant growth under low-water potential stress and for regulation of jasmonic acid and auxin-related gene expression as well as expression of developmental regulators includingShootmeristemless. These genes were also misregulated inhai1-2. AHL10 S314 phosphorylation was required for AHL10 complexes to form foci within the nucleoplasm, suggesting that S314 phosphorylation may control AHL10 association with the nuclear matrix or with other transcriptional regulators. These data identify a set of HAI1-affected phosphorylation sites, show that HAI1-regulated phosphorylation of AHL10 S314 controls AHL10 function and localization, and indicate that HAI1-AHL10 signaling coordinates growth with stress and defense responses.

Phosphoproteomics of Arabidopsis Highly ABA-Induced1 identifies AT-Hook Like10 phosphorylation required for stress growth regulation

The Clade A protein phosphatase 2C Highly ABA-Induced 1 (HAI1) plays an important role in stress signaling yet little information is available on HAI1-regulated phosphoproteins. Quantitative phosphoproteomics identified phosphopeptides of increased abundance in hai1-2 in unstressed plants and in plants exposed to low water potential (drought) stress. The identity and localization of the phosphoproteins as well as enrichment of specific phosphorylation motifs indicated that these phosphorylation sites may be regulated directly by HAI1 or by HAI1-regulated kinases including Mitogen-Activated Protein Kinases (MPKs), Sucrose-non fermenting Related Kinase 2 (SnRK2s) or Casein Kinases. One of the phosphosites putatively regulated by HAI1 was S313/S314 of AT Hook-Like10 (AHL10), a DNA binding protein of unclear function. HAI1 could directly dephosphorylate AHL10 in vitro and the level of HAI1 expression affected the abundance of phosphorylated AHL10 in vivo. AHL10 S314 phosphorylation was critical for restriction of plant growth under low water potential stress and for regulation of Jasmonic Acid and Auxin-related gene expression as well as expression of developmental regulators including Shootmeristemless (STM). These genes were also mis-regulated in hai1-2. AHL10 S314 phosphorylation was required for AHL10 complexes to form foci within the nucleoplasm, suggesting that S314 phosphorylation may control AHL10 association with the nuclear matrix or with other transcriptional regulators. These data identify a set of HAI1-affected phosphorylation sites, show that HAI1-regulated phosphorylation of AHL10 S314 controls AHL10 function and localization and also indicate that HAI1-AHL10 signaling coordinates growth with stress and defense responses.