Physiological and Molecular Characterization of the Differential Response of Broccoli (Brassica oleracea var. Italica) Cultivars Reveals Limiting Factors for Broccoli Tolerance to Drought Stress

Abstract

Broccoli is a cruciferous crop rich in health-promoting metabolites. Due to several factors, including anthropogenic global warming, aridity is increasing in many cultivation areas. There is a great demand to characterize the drought response of broccoli and use this knowledge to develop new cultivars able to maintain yield under water constraints. The aim of this study is to characterize the drought response at the physiological and molecular level of different broccoli ( Brassica oleracea L . var. Italica Plenck) cultivars, previously characterized as drought-sensitive or drought-tolerant. This approach aims to identify different traits, which can constitute limiting factors for drought stress tolerance in broccoli. For this purpose, we have compared several physiological parameters and the complete profiles of amino acids, primary metabolites, hormones, and ions of drought-tolerant and drought-sensitive cultivars under stress and control conditions. We have found that drought-tolerant cultivars presented higher levels of methionine and abscisic acid and lower amounts of urea, quinic acid, and the gluconic acid lactone. Interestingly, we have also found that a drought treatment increases the levels of most essential amino acids in leaves and in florets. Our results have established physiological and molecular traits useful as distinctive markers to predict drought tolerance in broccoli or which could be reliably used for breeding new cultivars adapted to water scarcity. We have also found that a drought treatment increases the content of essential amino acids in broccoli.

Comparative Metabolic Study of Two Contrasting Chinese Cabbage Genotypes under Mild and Severe Drought Stress

“…However, the level of quinic acid decreased in both genotypes under mild drought and further decreased with the aggravation of drought in DT. This result was in accordance with a report on broccoli [ 22 ], Salvia miltiorrhiza Bunge (Danshen) [ 44 ], peach [ 45 ] and maize [ 46 ]. Especially in broccoli, low levels of quinic acid were considered to be an important signature of drought tolerance [ 22 ].…”

“…This result was in accordance with a report on broccoli [ 22 ], Salvia miltiorrhiza Bunge (Danshen) [ 44 ], peach [ 45 ] and maize [ 46 ]. Especially in broccoli, low levels of quinic acid were considered to be an important signature of drought tolerance [ 22 ]. Consequently, the effect of quinic acid in response to drought needs to be further studied.…”

“…Proline has been reported in multiple studies as another important drought−responsive metabolite [ 13 , 21 , 22 , 23 ]. Beyond acting as an osmolyte for osmotic adjustment, proline also stabilizes sub−cellular structures and contributes to reactive oxygen species (ROS) detoxification [ 24 ].…”

BolTLP1, a Thaumatin-like Protein Gene, Confers Tolerance to Salt and Drought Stresses in Broccoli (Brassica oleracea L. var. Italica)

“…Broccoli pre-treating with SA and chitosan showed the highest drought stress recovery in a dose-dependent manner [27]. Drought-tolerant broccoli cultivars presented higher levels of methionine and ABA than that of the drought-sensitive cultivars [28]. 42 putative known and 39 putative candidate miRNAs displayed differentially expressed patterns between control and salt-stressed broccoli [29].…”

Distinctive Traits for Drought and Salt Stress Tolerance in Melon (Cucumis melo L.)

“…Several strategies have been developed to identify the limiting factors for stress tolerance. Evaluating the physiological and biochemical response of stress tolerant and stress sensitive plants is a well-established strategy to discover differential traits for abiotic stress tolerance (Taibi et al, 2017(Taibi et al, , 2018Chevilly et al, 2021). All these analyses have been performed testing different cultivars from the same variety and a single stress.…”