Seed aging and mobilization of stored resources in seed

Seed aging and mobilization of stored resources in seed during seed aging

1. SEED AGING & MOBILIZATION OF THE STORED RESOURCES IN SEED Submitted to : Dr. Rajendra Kumar Panda Department of Plant Physiology Submitted by: Gyana Ranjan Mohanty Adm no: 221222106 Dept. of Genetics & Plant Breeding College of Agriculture, Bhubaneswar, OUAT

2. What is seed aging ? It is a natural process that occur over time,leading to a decline in seed viability & vigour . Refers to detoriation of seed quality over time due to env . Factor ( temperature,humidity,and oxygen level). Ultimately affecting germination and seedling establishment.

3. Factor influencing seed aging Internal factor of seed : Genetic factor Maturational and Harvest condition Relative Humidity and Temperature Biochemical changes ( i ) ROS damage: Generated By A) Mitochondrial Respiration B) Lipid Peroxidation C) Protein Oxidation D) Enzymatic Reaction : Oxidoreductase , Peroxidases (ii) LIPID peroxidation & Damage to DNA sequences (iii)loss of DNA integrity & enzyme activity

4. Mobilization of stored resources CARBOHYDRATE: Stored in the form of starch starch Glucose Mitochondrial Respiration ATP synthesis (seed metabolism) & Byproduct : super oxide radicle convert to ROS Enzymatic activity(hydrolysis) Amylase Glysolysis pyruvate oxid . Krebs cyc . ETC Electron leak from ETC

5. PROTEIN : normally protein break down to Amino acid by protease enzyme which used for energy production through gluconeogenesis / TCA cycle for respiration of seed. ROS attack protein modification/ protein carbonylation protein degradation loss of function of protein and generation of additional ROS By exposed to oxidative stress Leads to disease, aging, cellular damage

6. Protein carbonylation It is a form of post translational modification that occurs where ROS leads to addition of a carbonyl group to proteins, when protein exposed to oxidative stresss . It involves : 1) Direct Oxidation : to side chain sulfur ( cysteine ) , nitrogen( lysin ). 2)indirect oxidation :by lipid peroxidation 3) metal-catalyzed oxidation : Fe & Cu bounds Carbonyl + protein inactivation of enzyme

7. Lipid : it is stored in triacyl glyceride , are hydrolysed into glycerol & fatty acid. Where by β -oxidation 2acetyl co-A is produced. Then by gluconeogenesis , glucose is produced and metabolic activity continue normally. But during seed aging with presence of ROS, unsaturated fatty acid react with ROS produce lipid hydroperoxides with hydroxyl radicle . (lipid peroxidation )

8. REACTION DURING LIPID PEROXIDATION Lipid molecule(RH) + ROS L* + ROS L* + O2 LOO*(PEROXYL RADICLE) LOO* + RH LOOH(Lipid peroxide)+ L* +ROS LOOH LOO* + H LOO* + LOO* 02 + LO-LO(non radicle ) L* + L* L-L

9. Lipid peroxidation Steps: presence of unsaturated fatty acid presence of reactive oxygen species ROS attack double bond in fatty acid L* react with ROS produce peroxide radicle and attack nearby fatty acid Termination by antioxidant enzyme, neutrilize free radicle Produced lipid radicle Produced lipid hydroperoxide

10. CONSEQUENCES Disruption of cell membrane integrity Generation of toxic byproduct ( aldehyde ) Loss of cell integrity Loss of enzyme activity Reduce respiration Reduce vigour and viability Darkening of seed coat and loss of stored materials.

11. Case study Mobilization of Stored protein in Aged maize Seeds: A study conducted by Radha et al. (2014) investigated the mobilization of stored quality& quantity in aged maize seeds and its impact on seedling establishment. The researchers subjected maize seeds to accelerated aging conditions and analyzed changes in seed composition and germination behavior. They found that aged seeds exhibited a significant decrease in total soluble protein content, accompanied by an increase in protein degradation products. This shift in stored resource utilization affected the metabolic profile of germinating seeds, leading to delayed germination and reduced seedling vigor & viability . The study highlights the importance of understanding seed aging processes and their implications for crop performance.

12. CONCLUSION Seed is the first link in the food chain and the ultimate symbol of food security . Understanding the mechanisms of seed aging will lead to new methods for seed conservation and longevity.  The primary cause of such losses is poor storage at harvest and damp storage conditions . Moisture content of seed, storage oxygen, relative humidity and temperature are the most important factors in storage which greatly influence the longevity and storability of seed Seed aging has become a global issue, with consequences that are highly unfavorable for the economy , as the loss of seed viability translates into a lack of material for reproduction. Which adversely affects agricultural productivity and food security for the rising population.Understanding factors influencing of seed ageing provides effective way to delay the deleterious effect of seed ageing and thereby improve the storage potential of the seed lot. Scientific and intelligent post harvest handling approach would not only delay the ageing effect but would also reduce the deteriorative impact of ageing on seed. Seeds possess a wide range of systems (protection, detoxification, repair) allowing them to survive in the dry state and to preserve a high germination ability. Therefore, the seed system provides an appropriate model to study longevity and aging

13. REFERENCES Radha,B.N ., Channakeshava , B.C, Hullur , N., Gowda , P. K.T., Bhanuprakash,K ., Ramachandrappa , B.K., & Munirajappa , R.,(2014). Effect Of Seed Ageing On Protein Quality And Quantity In Maize , Internation journal of bioassays,3(01),1708-13. https://www.cambridge.org/core/journals/seed-science-research/article/understanding-the-mechanisms-and-kinetics-of-seed https://www.mdpi.com/journal/plants/special_issues/D9Z943D456 https://www.researchgate.net/publication/358284718_Seed_Ageing_and_Mechanisms_involved https://www.slideshare.net

14. THANK YOU