Plant Molecular Biology Lab, Department of Botany, University of Kashmir, Srinagar, Kashmir, 190 006, India.
BMC Plant Biol. 2023 Apr 5;23(1):183. doi: 10.1186/s12870-023-04198-8.
Low temperature (LT) stress is one of the major environmental stress factors affecting the growth and yield of maize (Zea mays L.). Hence, it is important to unravel the molecular mechanisms behind LT stress tolerance to improve molecular breeding in LT tolerant genotypes. In the present study, two maize genotypes viz. Gurez local from Kashmir Himalaya and tropical grown GM6, were dissected for their LT stress response in terms of accumulation of differentially regulated proteins (DRPs). Leaf proteome analysis at three-leaf stage of maize seedlings subjected to LT stress of 6 °C for a total of 12 h duration was performed using two dimensional gel electrophoresis (2D-PAGE) followed by subsequent identification of the proteins involved.
After MALDI-TOF (Matrix-assisted laser desorption/ionization-time of flight) and bioinformatics analysis, 19 proteins were successfully identified in Gurez local, while as 10 proteins were found to get successful identification in GM6. The interesting observations from the present investigation is the identification of three novel proteins viz. threonine dehydratase biosynthetic chloroplastic, thylakoidal processing peptidase 1 chloroplastic, and nodulin-like protein, whose role in abiotic stress tolerance, in general, and LT stress, in particular, has not been reported so far. It is important to highlight here that most of LT responsive proteins including the three novel proteins were identified from Gurez local only, owing to its exceptional LT tolerance. From the protein profiles, obtained in both genotypes immediately after LT stress perception, it was inferred that stress responsive protein accumulation and their expression fashion help the Gurez local in seedling establishment and withstand unfavorable conditions as compared to GM6. This was inferred from the findings of pathway enrichment analysis like regulation of seed growth, timing of floral transition, lipid glycosylation, and aspartate family amino acid catabolic processes, besides other key stress defense mechanisms. However, in GM6, metabolic pathways enriched were found to be involved in more general processes including cell cycle DNA replication and regulation of phenylpropanoid metabolism. Furthermore, majority of the qRT-PCR results of the selected proteins demonstrated positive correlation between protein levels and transcript abundance, thereby strengthening our findings.
In conclusion, our findings reported majority of the identified proteins in Gurez local exhibiting up-regulated pattern under LT stress as compared to GM6. Furthermore, three novel proteins induced by LT stress were found in Gurez local, requiring further functional validation. Therefore, our results offer more insights for elucidating the molecular networks mediating LT stress tolerance in maize.
低温（LT）胁迫是影响玉米（Zea mays L.）生长和产量的主要环境胁迫因素之一。因此，揭示 LT 胁迫耐受的分子机制对于提高 LT 耐受基因型的分子育种至关重要。本研究以克什米尔喜马拉雅山的古雷兹地方品种和热带生长的 GM6 两个玉米基因型为材料，研究其在 LT 胁迫下的差异表达蛋白（DRPs）积累情况，以探讨其 LT 胁迫响应。采用二维凝胶电泳（2D-PAGE）分析玉米幼苗三叶期叶片蛋白质组，在 6°C 下共处理 12 小时，随后对参与的蛋白质进行鉴定。
经 MALDI-TOF（基质辅助激光解吸/电离时间飞行）和生物信息学分析，在古雷兹地方品种中成功鉴定出 19 种蛋白，而在 GM6 中成功鉴定出 10 种蛋白。本研究的有趣发现是鉴定出三种新蛋白，即苏氨酸脱水酶生物合成质体、类囊体加工肽酶 1 质体和类豆球蛋白，它们在非生物胁迫耐受中的作用，特别是在 LT 胁迫中的作用，迄今为止尚未报道。重要的是要在这里强调，包括三种新蛋白在内的大多数 LT 反应蛋白仅在古雷兹地方品种中被鉴定出来，这归因于其异常的 LT 耐受性。从两种基因型在 LT 胁迫感知后立即获得的蛋白质图谱推断，胁迫反应蛋白的积累及其表达方式有助于古雷兹地方品种幼苗的建立，并使其能够抵御不利条件，而 GM6 则不能。这是从途径富集分析中推断出来的，如种子生长的调控、花转变的时间、脂质糖基化和天冬氨酸家族氨基酸的分解代谢过程，以及其他关键的应激防御机制。然而，在 GM6 中，发现富集的代谢途径涉及更一般的过程，包括细胞周期 DNA 复制和苯丙烷代谢的调控。此外，选择蛋白的 qRT-PCR 结果多数显示蛋白质水平和转录丰度之间存在正相关，从而加强了我们的发现。
总之，我们的研究结果报告了大多数在 LT 胁迫下古雷兹地方品种中表达上调的鉴定蛋白，而 GM6 则表达下调。此外，在古雷兹地方品种中发现了三种由 LT 胁迫诱导的新蛋白，需要进一步的功能验证。因此，我们的研究结果为阐明玉米 LT 胁迫耐受的分子网络提供了更多的见解。
