Jasmonate-insensitive mutant jar1b prevents petal elongation and flower opening coupling with parthenocarpic fruit development in Cucurbita pepo

• Published in: Plant physiology and biochemistry Vol. 214; p. 108923
• Main Authors: Gautam, Keshav, Segura, María, Alonso, Sonsoles, Pasadas, Raúl, García-Mina, José M., Zamarreño, Angel M., Martínez, Cecilia, Jamilena, Manuel
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.09.2024
• Subjects: Acetates - pharmacology; Anthesis; BSA-sequencing; Cucurbita - genetics; Cucurbita - growth & development; Cyclopentanes - metabolism; Cyclopentanes - pharmacology; Flower opening; Flowers - drug effects; Flowers - genetics; Flowers - growth & development; Fruit - genetics; Fruit - growth & development; Fruit - metabolism; Gene Expression Regulation, Plant - drug effects; Isoleucine - analogs & derivatives; Isoleucine - metabolism; Isoleucine - pharmacology; Jasmonate; Mutation; Oxylipins - metabolism; Oxylipins - pharmacology; Parthenocarpy; Petal elongation; Plant Growth Regulators - metabolism; Plant Growth Regulators - pharmacology; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Parthenocarpy; Petal elongation; BSA-sequencing; Jasmonate; Flower opening; Anthesis
• ISSN: 0981-9428; 1873-2690; 1873-2690
• DOI: 10.1016/j.plaphy.2024.108923

Jasmonates are growth regulators that play a key role in flower development, fruit ripening, root growth, and plant defence. The study explores the coordination of floral organ maturation to ensure proper flower opening for pollination and fertilization. A new mutant (jar1b) was discovered, lacking petal elongation and flower opening but showing normal pistil and stamen development, leading to parthenocarpic fruit development. The mutation also enhanced the elongation of roots while reducing the formation of root hairs. BSA sequencing showed that jar1b is a missense mutation in the gene CpJAR1B, which encodes the enzyme that catalyzes the conjugation between JA and the amino acid isoleucine. The loss of function mutation in CpJAR1B produced a deficiency in biologically active (+) -7-iso-jasmonoyl-L-isoleucine (JA-Ile), which was not complemented by the paralogous gene CpJAR1A or any other redundant gene. Exogenous application of methyl jasmonate (MeJA) demonstrated that jar1b is partially insensitive to JA in both flowers and roots. Further experimentation involving the combination of JA-Ile deficient and ethylene-deficient, and ET insensitive mutations in double mutants revealed that CpJAR1B mediated ET action in female petal maturation and flower opening, but JA and ET have independent additive effects as negative regulators of the set and development of squash fruits. CpJAR1B also regulated the aperture of male flowers in an ethylene-independent manner. The root phenotype of jar1b and effects of external MeJA treatments indicated that CpJAR1B has a dual role in root development, inhibiting the elongation of primary and secondary roots, but promoting the formation of root hairs. •Jar1b is a missense mutation that reduces JA-Ile content and confers JA insensitivity.•Jar1b disrupts female- and male-flower opening, and promotes parthenocarpy.•The mutation jar1b enhances root elongation but supress the formation of root hairs.•The role of ET in flower opening is mediated by CpJAR1B in female but not male flowers.•JA and ET regulate negatively fruit set and development in an independent manner.