Metabolic responses to potassium availability and waterlogging reshape respiration and carbon use efficiency in oil palm

Abstract

Summary Oil palm is by far the major oil‐producing crop on the global scale, with c. 62 Mt oil produced each year. This species is a strong potassium (K)‐demanding species cultivated in regions where soil K availability is generally low and waterlogging due to tropical heavy rains can limit further nutrient absorption. However, the metabolic effects of K and waterlogging have never been assessed precisely. Here, we examined the metabolic response of oil palm saplings in the glasshouse under controlled conditions (nutrient composition with low or high K availability, with or without waterlogging), using gas exchange, metabolomics and proteomics analyses. Our results showed that both low K and waterlogging have a detrimental effect on photosynthesis but stimulate leaf respiration, with differential accumulation of typical metabolic intermediates and enzymes of Krebs cycle and alternative catabolic pathways. In addition, we found a strong relationship between metabolic composition, the rate of leaf dark respiration, and cumulated respiratory loss. Advert environmental conditions (here, low K and waterlogging) therefore have an enormous effect on respiration in oil palm. Leaf metabolome and proteome appear to be good predictors of carbon balance, and open avenues for cultivation biomonitoring using functional genomics technologies.

δ15N values in plants are determined by both nitrate assimilation and circulation

“…Such a situation was particularly visible in sunflower (Fig. 4) and is consistent with the general depressing effect of waterlogging on N metabolism in roots in both species but also on leaf‐exported N assimilates such as asparagine (Cui et al , 2019a,b).…”

“…Plant cultivation conditions were as in Cui et al (2019a,b). Briefly, sunflower ( Helianthus annuus L., var.…”

“…We chose these two species because they usually grow in regions where K deficiency and waterlogging can occur simultaneously. In addition, their metabolic response to both K limitation and waterlogging (including N metabolism) has been described recently (Cui et al , 2019a, b), and they are large enough to collect sufficient sample weight for nitrate purification. Manipulating potassium availability and waterlogging allowed us to change N assimilation and nitrate partitioning, while the availability and δ 15 N of source nitrate were kept constant.…”

What is the role of putrescine accumulated under potassium deficiency?

“…For instance, in oil palm putrescine concentration is ca. 60 μM at high K + and 1.8 mM at low K + (i.e., ≈ 7 μmol g DW −1 ; Figure S1; Cui, Davanture, et al, ). Conversely, high (>10 mM) external K + causes a decrease in putrescine content, which is converted to ‘higher polyamines’ (this term refers to higher molecular weight polyamines synthesized from putrescine, such as spermine and spermidine; Aurisano, Bertani, Mattana, & Reggiani, ; Reggiani, Aurisano, Mattana, & Bertani, ) and/or putrescine extrusion (Tamai, Shimada, Sugimoto, Shiraishi, & Oji, ).…”

“…That is, quite counter‐intuitively, K + deficiency implies an extra demand in negative charges to reach electro‐neutrality, which is met by accumulated organic and amino acids (Armengaud et al, ). The excess of positive charges mostly comes from the considerable increase in Ca 2+ (up to twofold increase) and Mg 2+ (more than twofold) in oil palm and sunflower (Cui, Abadie, et al, ; Cui, Davanture, et al, ). Under K + deficiency, there is also an increase in the difference between Ca 2+ and the sum Mg 2+ + K + (of about 0.4 mmol positive charges g −1 DW in Figure ).…”