Figures (1)  Tables (1)

    • Figure 1. 

      Auxin mediated cucumber growth and development. Auxin genes involved in the modulation of cucumber developmental stages has been presented in each box. (a) In roots, the auxin signaling genes (CsIAA2, CsARF8, CsARF17), auxin biosynthesis genes (CsYUCCA3, CsYUCCA5) and auxin transporting gene (CsPIN5) are shaping its structure and directional growth. (b) Majority of the auxin signaling genes (CsIAA4, CsIAA14, CsIAA29, CsIAA32, CsSAUR23 and CsSAUR32) are the main drivers of the hypocotyl length. (c) For shoot development, the auxin transporting gene CsPIN3 regulate the IAA accumulation in the wildtype cultivar hardwickii. Reduced IAA accumulation intensified the shoot branching in hardwickii. (d) The upregulation of CsYUCCA4 in v-2 mutant caused the rolled phenotype by inducing the IAA accumulation. (e) Suppression of auxin signaling genes SAUR and IAA/AUX resulted in the tendril-less phenotype in mutant line CG9192. (f) The enhanced expression of auxin biosynthesis genes (CsYUCCA2 and CsYUCCA10) amplified the IAA accumulation, increased the number of petals in male and female flower bud. (g) The higher accumulation of IAA in fruit caused its length to increase. The curved fruit phenotype was caused by the asymmetric distribution of IAA in the concave and convex side of the fruit.

    • StressAuxin activityFunctionsReference
      HeatCsYUC8, CsYUC9 ↑Enhanced IAA accumulation under high temperature stress.[68]
      IronYUC1, PIN1 ↑Higher expression of PIN1 gene increased cucumber tolerance.[70]
      WaterloggingIAA accumulation ↑Boosted AR formation, ethylene accumulation, and expression of CsRBOHB and CsRBOHF3.[71]
      Cold
      		CsYUCCA2 ↑Decrease harmful ROS and stress-induced electrolyte leakage.[75]
      CsARF6 ↑Activating the expression of cold stress-responsive gene CsDREB3.[76]
      Salinity
      		AUX/IAA ↓Reversed the harmful effects of salinity stress.[79]
      Csa6G104650 ↑Regulate the silicon-mediated salinity resistance.[81]
      DroughtIAA accumulation ↓CO2 suppressed the IAA accumulation and boosted GA.[83]
      CadmiumABP19a-like ↑Improve photosynthesis and antioxidant enzyme activities.[85]
      Powdery mildewCsIAA4, CsIAA6 ↓Suppressed auxin signaling hinders the pathogenicity of powdery mildew pathogen.[88]
      Downy mildewIAA accumulation ↑Positive regulation of the salicylic acid pathway.[91]
      NematodeAuxin transport ↓Augmented flavonoid biosynthesis inhibited the formation of the giant cell on the root.[93]
      Downregulated = ↓, Upregulated = ↑.

      Table 1. 

      Auxin participation in regulating cucumber response to multiple stresses.