Li Yan, Duan Baoli, Chen Juan, Korpelainen Helena, Niinemets Ülo, Li Chunyang
Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, Sichuan, China.
The Nurturing Station for the State Key Laboratory of Subtropical Silviculture, Zhejiang A & F University, Lin'an 311300, Zhejiang, China.
Tree Physiol. 2016 Dec;36(12):1573-1584. doi: 10.1093/treephys/tpw070. Epub 2016 Sep 1.
Sexual competition among dioecious plants affects sex ratios and the spatial distribution of the sexes in different environments. At present, little is known about sexual dimorphisms induced by different competition patterns under salinity stress. We employed Populus deltoides as a model to investigate sex-related growth as well as physiological and biochemical responses to salinity stress under conditions of intrasexual and intersexual competition. Potted seedlings (two seedlings per pot; two females, two males, or one female and one male) were exposed to two salt levels (0 and 50 mM NaCl) and salinity- and competition-driven differences in growth, assimilation rate, water use, contents of leaf pigments and osmotica, hydrogen peroxide (HO), and antioxidant enzyme and nitrate reductase activity were examined. In the absence of salinity, no significant differences in competitive ability between males and females subjected to intrasexual competition were observed, although the growth of females was moderately greater under intersexual competition. The salinity treatment significantly increased the sex differences in competitive ability, especially under intersexual competition. Under salinity stress, males showed decreased height, but displayed greater capacity for osmotic adjustment, enhancement of long-term water-use efficiency and increase in antioxidant enzyme activities. The absolute values of these traits were greater in salt-stressed males than in females under intersexual competition. In addition, salt-stressed males accumulated less Cl and had lower HO contents than females. These data collectively demonstrate that the competitive advantage of females in non-stressed conditions is lost under salinity. Greater salinity resistance of males growing intermixed with females under salt stress can importantly affect the sex ratio of P. deltoides populations.
雌雄异株植物之间的性竞争会影响不同环境下的性别比例和性别的空间分布。目前，对于盐胁迫下不同竞争模式所诱导的性二态性知之甚少。我们以三角叶杨为模型，研究了在同性和异性竞争条件下与性别相关的生长以及对盐胁迫的生理生化响应。将盆栽幼苗（每盆两棵；两棵雌株、两棵雄株或一雌一雄）暴露于两种盐浓度水平（0和50 mM NaCl）下，检测了盐度和竞争驱动的生长、同化率、水分利用、叶片色素和渗透物质含量、过氧化氢（H₂O₂）以及抗氧化酶和硝酸还原酶活性的差异。在无盐胁迫时，尽管在异性竞争下雌株生长略快，但在同性竞争中，未观察到雄株和雌株在竞争能力上有显著差异。盐处理显著增加了竞争能力的性别差异，尤其是在异性竞争下。在盐胁迫下，雄株高度降低，但表现出更强的渗透调节能力、长期水分利用效率的提高以及抗氧化酶活性的增加。在异性竞争下，盐胁迫雄株的这些性状绝对值大于雌株。此外，盐胁迫下雄株积累的Cl较少，H₂O₂含量低于雌株。这些数据共同表明，在盐胁迫下，雌株在非胁迫条件下的竞争优势丧失。盐胁迫下与雌株混生的雄株更强的耐盐性会显著影响三角叶杨种群的性别比例。
