Bailey Amanda, Burkey Kent, Taggart Matthew, Rufty Thomas
USDA-ARS, Plant Science Research Unit, Raleigh, ND 27695-7631, USA.
Crop and Soil Sciences Department, North Carolina State University, Raleigh, ND 27695-7620, USA.
Plants (Basel). 2019 Jul 20;8(7):235. doi: 10.3390/plants8070235.
Ozone (O) is a phytotoxic air pollutant that limits crop productivity. Breeding efforts to improve yield under elevated O conditions will benefit from understanding the mechanisms that contribute to O tolerance. In this study, leaf gas exchange and antioxidant metabolites were compared in soybean genotypes (Glycine max (L.) Merr) differing in ozone sensitivity. Mandarin (Ottawa) (O-sensitive) and Fiskeby III (O-tolerant) plants grown under charcoal-filtered (CF) air conditions for three weeks were exposed for five days to either CF conditions or 70 ppb O in continuously stirred tank reactors (CSTRs) in a greenhouse. In the CF controls, stomatal conductance was approximately 36% lower for Fiskeby III relative to Mandarin (Ottawa) while the two genotypes exhibited similar levels of photosynthesis. Ozone exposure induced significant foliar injury on leaves of Mandarin (Ottawa) associated with declines in both stomatal conductance (by 77%) and photosynthesis (by 38%). In contrast, O exposure resulted in minimal foliar injury on leaves of Fiskeby III with only a small decline in photosynthesis (by 5%), and a further decline in stomatal conductance (by 30%). There was a general trend towards higher ascorbic acid content in leaves of Fiskeby III than in Mandarin (Ottawa) regardless of treatment. The results confirm Fiskeby III to be an O-tolerant genotype and suggest that reduced stomatal conductance contributes to the observed O tolerance through limiting O uptake by the plant. Reduced stomatal conductance was associated with enhanced water-use efficiency, providing a potential link between O tolerance and drought tolerance.
臭氧（O₃）是一种对植物有毒的空气污染物，会限制作物产量。了解有助于耐臭氧的机制，将有利于在臭氧浓度升高条件下提高产量的育种工作。在本研究中，对臭氧敏感性不同的大豆基因型（Glycine max (L.) Merr）的叶片气体交换和抗氧化代谢产物进行了比较。在温室中，将在活性炭过滤（CF）空气条件下生长三周的普通话（渥太华）（对臭氧敏感）和菲斯克比III（耐臭氧）植株，在连续搅拌槽式反应器（CSTRs）中，暴露于CF条件或70 ppb臭氧环境中5天。在CF对照中，菲斯克比III的气孔导度相对于普通话（渥太华）约低36%，而两种基因型的光合作用水平相似。臭氧暴露导致普通话（渥太华）叶片出现明显的叶损伤，同时气孔导度（下降77%）和光合作用（下降38%）均降低。相比之下，臭氧暴露对菲斯克比III叶片造成的叶损伤最小，仅光合作用略有下降（5%），气孔导度进一步下降（30%）。无论处理如何，菲斯克比III叶片中的抗坏血酸含量总体上都高于普通话（渥太华）。结果证实菲斯克比III是一种耐臭氧基因型，并表明气孔导度降低通过限制植物对臭氧的吸收，有助于观察到的耐臭氧性。气孔导度降低与水分利用效率提高有关，这为耐臭氧性和耐旱性之间提供了潜在联系。
