Comparative Proteomic and Morpho-Physiological Analyses of Maize Wild-Type Vp16 and Mutant vp16 Germinating Seed Responses to PEG-Induced Drought Stress

Abstract

Drought stress is a major abiotic factor compromising plant cell physiological and molecular events, consequently limiting crop growth and productivity. Maize (Zea mays L.) is among the most drought-susceptible food crops. Therefore, understanding the mechanisms underlying drought-stress responses remains critical for crop improvement. To decipher the molecular mechanisms underpinning maize drought tolerance, here, we used a comparative morpho-physiological and proteomics analysis approach to monitor the changes in germinating seeds of two incongruent (drought-sensitive wild-type Vp16 and drought-tolerant mutant vp16) lines exposed to polyethylene-glycol-induced drought stress for seven days. Our physiological analysis showed that the tolerant line mutant vp16 exhibited better osmotic stress endurance owing to its improved reactive oxygen species scavenging competency and robust osmotic adjustment as a result of greater cell water retention and enhanced cell membrane stability. Proteomics analysis identified a total of 1200 proteins to be differentially accumulated under drought stress. These identified proteins were mainly involved in carbohydrate and energy metabolism, histone H2A-mediated epigenetic regulation, protein synthesis, signal transduction, redox homeostasis and stress-response processes; with carbon metabolism, pentose phosphate and glutathione metabolism pathways being prominent under stress conditions. Interestingly, significant congruence (R2 = 81.5%) between protein and transcript levels was observed by qRT-PCR validation experiments. Finally, we propose a hypothetical model for maize germinating-seed drought tolerance based on our key findings identified herein. Overall, our study offers insights into the overall mechanisms underpinning drought-stress tolerance and provides essential leads into further functional validation of the identified drought-responsive proteins in maize.

Comparative transcriptomic analysis of contrasting hybrid cultivars reveal key drought-responsive genes and metabolic pathways regulating drought stress tolerance in maize at various stages

“…Contrastingly, PGI and MAPK signaling pathways were the top most significantly enriched in the sensitive hybrid line ZX978 at the VT stage after drought treatment (Fig 2B). Similarly, in our previous report, PGI pathway was significantly enriched in drought sensitive wide-type Vp16 maize line in response to osmotic stress [51]. Further, the PGI pathway has been reported to be significantly enriched in cotton under drought stress [52].…”

Label-Free Comparative Proteomic Analysis Combined with Laser-Capture Microdissection Suggests Important Roles of Stress Responses in the Black Layer of Maize Kernels

“…Neighboring inside the BL is an endosperm tissue called BETL, and outside is a pericarp IEP. The proteome of whole maize seeds, embryos, and endosperm has been intensively investigated in recent decades [23,25,[38][39][40][41][42][43][44]. Due to the difficulty of separating tissues from kernels, the proteome for some targeted seed parts has seldom been the focus, except for BETL, whose functions have been implied to mediate embryo-endosperm interactions and play a role in plant defense by this method [45][46][47][48] To date, no attempt has been focused on BL, and very little is known about its developmental processes, as well as the physiological and molecular roles of this tissue in kernel development.…”

DIA (Data Independent Acquisition) proteomic based study on maize filling-kernel stage drought stress-responsive proteins and metabolic pathways

“…This may suggest that both tools can be effectively used for proteomics analysis with comparably similar success. However, a higher number of unique peptides (87,018) was identified by iTRAQ [38] as compared to significantly fewer peptides (36,717) identified by DIA in this paper. Additionally, the iTRAQ approach detected a higher number of DAPs (1655), although it had fewer (9895) total proteins [38].…”

“…Earlier, we employed the isobaric tags for absolute quantification (iTRAQ) strategy to perform proteomics analysis and identify key proteins and metabolic pathways regulating the drought stress response in maize [35][36][37][38]. We observed diverse key drought responsive proteins, including chlorophyll a-b binding proteins (Lhcb5-1 and 542320/Lhcb5-2) associated with the light-harvesting complex; lipid metabolism related non-specific lipid transfer proteins [35]; histone H2A proteins (Zm00001d006547, 100216750), carbohydrate metabolism-related protein malate dehydrogenase (MDH; Zm00001d009640) and several peroxidases [36]; histone deacetylase (HDAC), HSPs, MDH, GSTs, seed storage proteins 50kD c-zein, Z1D alpha zein [37]; peroxidase (Zm00001d008898), stress responsive protein (100283176) and oxidoreductase family proteins [38]. Notably, these genes and proteins were mainly involved in photosynthesis antenna proteins, nitrogen metabolism, secondary metabolism related pathways, especially in the tolerant maize genotype ND476 under drought stress [28,35,38].…”