Auxin and ethylene are essential in the tomato response to mechanical treatment

CASTRO, J; RAMALLO, ANA C.; SALAZAR, SERGIO; CABELLO JULIETA V.; FILIPPONE, MARÍA PAULA; CHAN RAQUEL L.; WELCHEN, ELINA

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology RAFV Conference 2023; 2023

Tomatoes are preferred and requested vegetables given their taste, nutritional, and antioxidant characteristics. Moreover, their production has enormous importance in several regional economies in our country. Improving this crop yield and fitness may impact family and small farmers’ establishments. Our group has previously shown that a mechanical treatment (MT) on the stem of 12-day-old tomato seedlings for 48 h resulted in a 25-30% enlargement of stem diameter, increasing fruit production. Upon histological analysis of stem cross-sections, we observed an increase in the stele area with morpho-anatomical modifications in the vascular bundles, which together with other unknown factors, conferred plant tolerance against Fusarium oxysporum (Fol). At the molecular level, we observed an induction of the expression of genes encoding for the Ethylene-forming enzyme SlACC and Auxin transporters SlLAX1 and SlLAX2, after the MT. To investigate the possible involvement of these hormones, we treated Ailsa Craig (AC) seedlings to MT with ethylene (ET) precursor ACC (10mM), a pathway inhibitor AgNO3 (100 µM), and auxins IAA (1 mM), a polar transport inhibitor NPA (1mM) for 48 h. The results indicated that both hormonal pathways are connected with the tomato response to MT. Moreover, we found that tomato mutants less sensitive to ET and auxins, Never ripe (Nr), and diageotropic (dgt), respectively, did not exhibit an increase in stem diameter after MT. Additionally, a double mutant between an ET-overproducer plant (epinastic, epi) and dgt (dgt/epi) did not incremented their stem diameter. In contrast, the epi and entire mutants, lacking an auxin signal repressor, showed wider stemsAltogether our observations strongly suggest that auxin is essential for MT response, and ethylene plays a crucial role too.