The phytohormones jasmonates (JAs) act as important molecules of elicitors for the chlorophyll degradation and anthocyanin biosynthesis. JAs do usually not act independently but integrate in complex networks linking to other hormonal signaling transduction. Here, the crosstalk was detected between the JAs (jasmonic acid) and abscisic acid (ABA) signaling pathways in the mediation of chlorophyll degradation and anthocyanin biosynthesis. In this study, we found that the ABA receptor mutants, pyr1pyl1pyl2pyl4 (1124) and pyr1pyl1ply2pyl4pyl5pyl8 (112458) showed less level of chlorophyll and anthocyanin than the wild-type plants, while gain-of-function of RCAR13 transgenic lines inhibited chlorophyll degradation and enhanced anthocyanin accumulation after MeJA treatment. The amidohydrolases, including ILL6 and IAR3 and cytochrome P450 (CYP94B3), encoding JA-Ile catabolism were markedly depressed by ABA receptors. While transcripts of the enzymes for activation of anthocyanin biosynthesis pathway were analyzed, the results indicating that JA biosynthetic genes, including allene oxide synthase (AOS), LOX3 and LOX4 were enhanced by the link of JAs and ABA receptors. Moreover, the ABA receptors are also involved in JAs signal transduction through the regulation of COI, JAZ and MYC2 transcripts. These findings elucidate a connection between a core component of the ABA signaling pathway and JA responses.

Actin depolymerization factors (ADFs), as actin-binding proteins, act a crucial role in plant development and growth, as well as in response to abiotic and biotic stresses. Here, we found that CARK3 plays a role in regulating hypocotyl development and links a cross-talk between actin filament and drought stress through interaction with ADF4. By using bimolecular fluorescence complementation (BiFC) and GST pull-down, we confirmed that CARK3 interacts with ADF4 in vivo and in vitro. Next, we generated and characterized double mutant adf4cark3-4 and OE-ADF4:cark3-4. The hypocotyl elongation assay indicated that the cark3-4 mutant seedlings were slightly longer hypocotyls when compared with the wild type plants (WT), while CARK3 overexpressing seedlings had no difference with WT. In addition, overexpression of ADF4 significantly inhibited long hypocotyls of cark3-4 mutants. Surprisingly, we found that overexpression of ADF4 markedly enhance drought resistance in soil when compared with WT. On the other hand, drought tolerance analysis showed that overexpression of CARK3 could rescue adf4 drought susceptibility. Taken together, our results suggest that CARK3 acts as a regulator in hypocotyl elongation and drought tolerance likely via regulating ADF4 phosphorylation.

Decreasing saturated fatty acids and increasing monounsaturated fatty acids are desirable to improve oil for food. Seed oil content and fatty acid composition are affected by genotype and environment. Therefore, we systematically analyzed the agronomic traits and fatty acid metabolic profiling of Brassica napus (B. napus) seeds at different developmental stages in high level of oleic acid (HOA), medium level of oleic acid (MOA), and low level of oleic acid (LOA) B. napus cultivars, both sown in winter and summer. The results showed that all winter-sown cultivars produced 20% more seed yield than the summer-sown crop. The longer growing period of winter-sown B. napus resulted in higher biomass production. However, the fatty acid metabolism of individual cultivars was different between winter-sown rape (WAT) and summer-sown rape (SAT). The absolute fatty acid content of LOA and MOA cultivars in WAT were significantly higher than that in SAT, but that of HOA was opposite. Importantly, the levels of monounsaturated fatty acids (18:1; 20:1) in SAT were far more than those in WAT. These data indicate the quality of oil from the HOA in SAT is more suitable for human consumption than that in WAT.