Sharma Sandeep, Sahu Ranabir, Navathe Sudhir, Mishra Vinod K, Chand Ramesh, Singh Pawan K, Joshi Arun K, Pandey Shree P
CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, India.
Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, India.
Front Plant Sci. 2018 May 16;9:636. doi: 10.3389/fpls.2018.00636. eCollection 2018.
Spot blotch, caused by the hemibiotropic fungus , is amongst the most damaging diseases of wheat. Still, natural variation in expression of biochemical traits that determine field resistance to spot blotch in wheat remain unaddressed. To understand how genotypic variations relate to metabolite profiles of the components of defense-signaling and the plant performance, as well as to discover novel sources of resistance against spot blotch, we have conducted field studies using 968 wheat genotypes at 5 geographical locations in South-Asia in 2 years. 46 genotypes were identified as resistant. Further, in independent confirmatory trials in subsequent 3 years, over 5 geographical locations, we re-characterized 55 genotypes for their resistance (above 46 along with Yangmai#6, a well characterized resistant genotype, and eight susceptible genotypes). We next determined time-dependent spot blotch-induced metabolite profiles of components of defense-signaling as well as levels of enzymatic components of defense pathway (such as salicylic acid (SA), phenolic acids, and redox components), and derived co-variation patterns with respect to resistance in these 55 genotypes. Spot blotch-induced SA accumulation was negatively correlated to disease progression. Amongst phenolic acids, syringic acid was most strongly inversely correlated to disease progression, indicating a defensive function, which was independently confirmed. Thus, exploring natural variation proved extremely useful in determining traits influencing phenotypic plasticity and adaptation to complex environments. Further, by overcoming environmental heterogeneity, our study identifies germplasm and biochemical traits that are deployable for spot blotch resistance in wheat along South-Asia.
由半活体营养型真菌引起的叶斑病，是小麦最具破坏性的病害之一。然而，决定小麦对叶斑病田间抗性的生化性状表达的自然变异仍未得到解决。为了了解基因型变异如何与防御信号成分的代谢物谱以及植物性能相关，以及发现抗叶斑病的新抗性来源，我们在两年内对南亚5个地理位置的968个小麦基因型进行了田间研究。鉴定出46个基因型具有抗性。此外，在随后三年的独立验证试验中，在5个以上地理位置，我们重新鉴定了55个基因型的抗性（46个以上，以及特征明确的抗性基因型扬麦6号和8个感病基因型）。接下来，我们确定了叶斑病诱导的防御信号成分的时间依赖性代谢物谱以及防御途径的酶成分水平（如水杨酸（SA）、酚酸和氧化还原成分），并得出了这55个基因型抗性的共变模式。叶斑病诱导的SA积累与病情进展呈负相关。在酚酸中，丁香酸与病情进展的负相关性最强，表明其具有防御功能，这一点得到了独立验证。因此，探索自然变异被证明在确定影响表型可塑性和适应复杂环境的性状方面非常有用。此外，通过克服环境异质性，我们的研究确定了可用于南亚小麦抗叶斑病的种质和生化性状。
