N-acetylcysteine absorption and its potential dual effect improve fitness and fruit yield in Xylella fastidiosa infected plants.

BACKGROUND: Xylella fastidiosa is a multi-host bacterium that can be detected in hundreds of plant species including several crops. Diseases caused by X. fastidiosa are considered a threat to global food production. The primary method for managing diseases caused by X. fastidiosa involves using insecticides to control the vector. Hence, it is necessary to adopt new and sustainable disease management technologies to control not only the insect but also the bacteria and plant health. We demonstrated that N-acetylcysteine (NAC), a low-cost cysteine analogue, is a sustainable molecule that can be used in agriculture to decrease the damage caused by X. fastidiosa and improve plant health. RESULTS: Using 15N-NAC we proved that this analogue was absorbed by the roots and transported to different parts of the plant. Inside the plant, NAC reduced the bacterial population by 60-fold and the number of xylem vessels blocked by bacterial biofilms. This reflected in a recovery of 0.28-fold of the daily sap flow compared to health plants. In addition, NAC-treated citrus variegated chlorosis (CVC) plants decreased the oxidative stress by improving the activity of detoxifying enzymes. Moreover, the use of NAC in field conditions positively contributed to the increase in fruit yield of CVC-diseased plants. CONCLUSION: Our research not only advances the understanding of NAC absorption in plants, but also indicates its dual effect as an antimicrobial and antioxidant molecule. This, in turn, negatively affects bacterial survival while improving plant health by decreasing oxidative stress. Overall, the positive field-based evidence supports the viability of NAC as a sustainable agricultural application. © 2024 Society of Chemical Industry.

Tangerineiras como porta-enxertos para laranjeira 'Pêra' / Mandarins as rootstocks for 'Pêra' sweet orange trees

Laranjeiras 'Pêra' enxertadas em 11 cultivares ou híbridos de tangerineiras foram plantadas em 1988 em Itirapina (SP), num Latossolo Vermelho-Amarelo textura arenosa, no espaçamento 4,25m x 7,5m e conduzidas sem irrigação sob clima Cwa. Tristeza e declínio são endêmicos na região. As tangerineiras 'África do Sul', 'Xienkhouanga', 'Empress', 'Cleópatra', 'Wildt', 117.477 e 'Sul da África', sem diferirem entre si, induziram, em ordem decrescente, as maiores produções de frutos às laranjeiras 'Pêra', no total das quatro primeiras colheitas do experimento. Num total de nove colheitas, as cultivares Xienkhouanga, África do Sul, 117.477, Cleópatra, Empress, Wildt e Szinkon x Tizon, sem diferirem entre si, proporcionaram, em ordem decrescente, as maiores produções de frutos às laranjeiras 'Pêra'. Os porta-enxertos não determinaram diferenças significativas nas características comerciais dos frutos, porém a 'Cleópatra' induziu maturação mais precoce que os demais porta-enxertos. Apenas a 'Szwinkon' x 'Szinkon-tizon' proporcionou a formação de plantas nanicas, com altura inferior a 2,5m. Os dados médios de produção de frutos e de sólidos solúveis, concernentes a três anos consecutivos de colheita, revelaram que as laranjeiras 'Pêra' enxertadas nas tangerineiras 'Xienkhouanga' e 117.477, sem diferir das plantas enxertadas nas cultivares África do Sul, Cleópatra, Empress, Wildt e Szinkon x Tizon, foram significativamente mais produtivas em frutos e em sólidos solúveis que as enxertadas em 'Sul da África', 'Vermelha', 'Muscia' e 'Szwinkon' x 'Szinkon-tizon'. Nenhuma das plantas apresentou sintomas de intolerância à tristeza, ao declínio dos citros ou anel de goma na região de enxertia, considerado sintoma de incompatibilidade entre a copa e o porta-enxerto.

'Pera' sweet orange trees budded either on mandarins or mandarin-hybrids rootstocks were planted in 1988 at 4.25m x 7.5m spacing on a sandy textured Oxisol in Sao Paulo state, Brazil, under Cwa climatic conditions, and managed without irrigation. Tristeza and blight diseases are endemic in the area. Trees on Africa do Sul, Xienkhouanga, Empress, Cleopatra, Wildt and 117.477 cultivars, produced the highest cumulative yields in the first four crops and in the ninth crop. Regardless of the rootstock tested no significant variation on fruit quality was observed, but 'Cleopatra' mandarin induced earlier maturation of fruit than the others roostocks. Only 'Szwinkon' x 'Szinkon-tizon' rootstocks induced dwarfed trees. 'Xienkhouanga', 117.477, 'Africa do Sul', 'Cleopatra', 'Empress', 'Wildt' and 'Szinkon' x 'Tizon' induced the highest fruit and soluble solids production by tree in the 1996-1999 period. No one trees showed symptoms of tristeza, declinio/blight or bud-union-ring symptom of incompatibility.