Physiological, Biochemical, and Molecular Response in Siete Caldos Chili Pepper Plants (Capsicum frutescens) Exposed to Water Deficit

Abstract

Drought, exacerbated by climate change, represents a growing challenge for agriculture, significantly impacting on crops such as chili peppers (Capsicum), essential in the global diet. This work evaluated the response to water stress by suspending irrigation in Siete Caldos chili pepper plants (Capsicum frutescens). Control plants were watered every 48 h, while stress was induced in the test plants by withholding irrigation for 14 days, followed by an evaluation of recovery through rehydration on day 15. Growth parameters such as the fresh weight of the aerial part, root length, and number of flower buds showed significant differences between the two groups from the eighth day onwards. However, physiologically and biochemically stress-induced decreased relative water content, membrane stability, and chlorophyll content, coupled with increased electrolyte leakage, proline content, and antioxidant activity (catalases and peroxidases), were observed starting on the third day. These effects were more severe on day 14. At the molecular level, the expression of stress response genes (AP2, LOX2, CAT, CuSOD, MnSOD, and P5CS) was quantified at days 3, 14, and 15, revealing differences in transcript levels between the treatments. Finally, rehydration in the stressed plants resulted in the recovery of the evaluated parameters and a survival rate of 100%. Therefore, chili pepper has tolerance mechanisms that allow it to withstand a period of 14 days without irrigation, without reaching its permanent wilting point, and it can recover if conditions improve. This study underscores the complexity of plant responses and tolerance mechanisms to drought, providing insights into the behavior of semi-domesticated species.